Note: Descriptions are shown in the official language in which they were submitted.
~ 37 HA135b
1 0
This invention relates to new proline derlvatives ~ .
and related compounds which have the general formula . ~;
(I) R
R4 Rl H2l (CH)m
;~ ~ R2- S - (~H)n- ~H - ~CO - N - CH-COR
wherein R is hydroXy~ NH2 or lower alkoxy~
Rl and R4:each is hydrogen, lower aIkyl,
phenyl or phenyl-lower alkyl; :.:
R2 is hydrogenj lower alkyl, phenyl, :
,
subs~itu~ed phenyl wherein the phenyl
substituent is halo, lower alkyl or
lower alkoxy, phenyl-lower alkyl,
diphenyl-lower alkyl, triphenyl-lower
alkyl, lower alkylthiomethyl, phenyl-
lower alkylthiomethyl, loMer alkanoMyl-
amidomethyl, R~-C-, R5-M-C-,R5-NH-C-~R6-S- or R7;
R3 is hydrogen,hydroxy or lower alkyl;
R5 is lower alkyl, phenyl or phenyl-lower
-1-
.'
~"
, . . . . .
, ~ ,
~' ' ,' ' ~ .
~z~37 HA135b
alkyl;
R6 is lower alkyl, ~henyl, substituted
phenyl, (wherein the phenyl su~stituent
is halo, lower alkyl or lower alkoxy), ~ ;
hydroxy-lower alkyl or amino(carboxy)- ~ ,
lower alkyl;
IR3
m(~C) - CH2 R1 R4
R7 is R-OC-HC - N - CO - CH - (CH)- S(O) ;
M is O or S;
m is 1 to 3;
n and p each is O to-2,
~ , -
and to processes for making them.
The asterisks indicate asymmetric carbon atoms.
~ ~
Each of the carbons bearing a substituent Rl, R3 and R
is asymmetric when that substituent is other than~hydrogen.
The invention in its broad aspects includes proline
and related derivatives having formula I above. Within this ;
broad group, because of their properties, certain subgroups
are preferred over others.
Broadly preferred are those compounds of formula I
wherein R is hydroxy or lower alkoxy; Rl is hydrogen or -~
lower alkyl; R2 is hydrogen, R5-CO, R6-S-, or R7; R3 and
R4 each is hydrogen; R5 is lower alkyl, especially methyl
or phenyl; R6 is lower alkyl, especially methyl or ethyl; ~ ;'i`
m is 2, n is 0, 1 or 2, especially 1; and R7 whèrein R, Rl,
R3, R4, m and n have the same preferences as above and p is 0.
,
~Z;~37
, .
Especially preferred are those compounds which have the
formula
(II) :
2 5 (CH2)n CH- CO~- N ~ COR
* *
wherein R is hydroxy or lower alkoxy;
Rl is hydrogen or lower alkyl; ;
R2 is hydrogen, R5-CO-, R6-S- or R7;
R5 is lower alkyl or phenyl, especially the first;
R6 is lower alkyl;
and n is 0, 1 or 2.
Within the group of compounds represented by formula
II, the following are stlll more ~referred subgrouFs in~
the order (a to r) of increasing preference to the com~
, .
pounds which are especially preferred embodiments~
a) R is hydroxy
- : :,
b) n is 1
c) R2 is hydrogen or lower alkanoyl
d) R2 is hydrogen
e) R2 is acetyl
f) Rl is hydrogen or lower alkyl
g) Rl is hydrogen or methyl
h) R is hydroxy, Rl is hydrogen or methyl :~
i) R is hydroxy, Rl is hydrogen or methyl, R2 is hydro-
gen or acetyl and n is 0, 1 or 2 . ;~
j) R is hydroxy, Rl and R2 each is hydrogen and n is 0 ~ :
:
,,,i~'~,
3~
k) R is hydroxy, Rl is hydrogen, R2 is acetyl and n is :'
1) R is hydroxy, Rl is methyl, R2 is acetyl and n is 1
m) R is hydroxy, Rl and R2 each is hydrogen and n is 1
n) R is hydroxy, Rl is methyl, R2 is hydrogen and n is
o) R is hydroxy, Rl is hydrogen, R2 is lower alkylthio
: and n is 1
p) R~ is
lo ~ 71 : ~
R-OC N OC~ CH - (CH2)n-S-; ;
each R is hydroxy; Rl is hydrogen or lower alkyl, es-
pecially hydrogen or methyl; and n is 0 to 2, es- ~
pecially 1 ' -'
M ~ :
q) R2 is R5-M-C- wherein M is O or S ~:
M
r) R~ is R5-NH-C- wherein M is O or S, pr,eferably~S. :
It will be appreciated that comblnations of the fore-
going, where applicable, are among the preferred groups. ,~
~0 The stereoisomers in which the proline is in the L-
form are especialLy preferred.
The lower alkyl groups represented by any of the vari-~ :
ables include straight and branched,chain hydrocarbon ~ '
radicals from methyl to heptyl, for example, methyl, ethyl,
propyl, isopropyl r butyl, isobutyl, t-butyl, pentyl, iso~
pentyl and the like. The lower alkoxy groups are of the
same kind having 1 to 7 carbons linked to oxygen, for ex-
ample, methoxy, ethoxy, propoxy, isopropoxy, butoxy, iso- "
butoxy, t-butoxy and the like. The Cl-C4 members, espe- ,
cially Cl and C2 members, o~ both
~' , '
'~
~lQ~ 7
HA135b
.:..
types are preferred. Phenylmethyl is the preferred phenyl-
lower alkyl group.
The lower alkanoyl groups are those having the acyl
radicals of the lower (C2-C7) fatty acids, for example,
acetyl, propionyl, butyryl, isobutyryl and the like. Similarly,
those lower alkanoyl groups having up to four carbons, and
especially acetyl, are preferred.
The four common halogens are included by the term ;~
'!halo" but chlorine and bromine are preferred. The substi-
tuted phenyl groups preferably bear the substituent in the
4-position of the ring. The hydroxy-lower alkyl groups
have a hydroxy group on an alkyl chain like those described
above, preferably on the terminal carbon, e.g., hydroxymethyl,
2-hydroxyethyl, etc. The amino(carboxy)lower alkyl groups
have one aminc and one carboxy on a lower alkyl group such
as those described above, preferably both on one carbon,
e.g., on the terminal carbon as in the preferred 2-amino-2- ~
carboxyethyl group. I;
The produc~s of formula I and the preferred subgroups
can be produced by various methods of synthesis.
In general, the products of this invention are
produced by acylating a compound of the formula
; .
(III)
13
H2C ( IcH)m
HN CH - COR
with an acid of the formula
(IV) IR4 1l
R2 - S - (CH)n - CH - COOH
.
~ 2~3~ ~ ~
HA135b
or its chemical equivalent.
Thus, the final product can be produced not only by direet
acylation with an acid of formula IV but also by interMediates
such as (a) ~-haloalkanoic acids of the formula
R R
(V) 14
X (C~)n ~ -CR - COOE~
wherein X is bromo, chloro or iodo, or (b) a tosyloxyalkanoie
aeid, i.e., X in formula V is tosyloxy (CH3 ~ SO2O-)
(c) a substituted acrylie aeid of the formula
T4 IRl
(VI) CH- - C COOH
The produet of this aeylation is then subjeeted to displacement
or addition with the anion of a thiol or thioaeid of the
formula
(VII) R2 - SH
Aeylation ean also be effected with a-thiolactone of the
formula -~
14
(VIII) (fH)n -CH
S =o
wherein n is 1 or 2, or a mercaptoalkanoie aeid of the formula
IR4 1 ~
(IX) Y - S - (C~)n - C~ - COR
-6-
,
,
., ., . ~ ~ .
~L(12;~3,~
HA135b
wherein Y is ~2 or, in addition, if a product of formula I
wherein R2 is hydrogen is desired, then Y can also be a
protecting group such as (a) CH30- ~ ~CH2-, (b) ~ ,
(c) CH3CONHCH2, (d) R-O-C-CH-(CH) -S- or other sulfur
protecting group. "Deprotection" can be effected by
conventional means such as treatment with hot trifluoroacetic
acid, cold trifluoromethanesulfonic acid, mercuric acetate,
sodium in liquid ammonia, zinc and hydrochloric acid or the
like. For a review of these methods see Methoden der
Organischen Chemie (Houben-Weylj, Vol. XV, part I, page
736 et seq. (1974).
When the acid of formula IV is used as the acylating
agent, the acylation can be effected in the presence of a
coupling agent like dicyclohexycarbodiimide or the like,
or the acid can be activated by formation of its mixed
anhydride t symmetrical anhydride, acid chloride, acid
ester or use of Woodward reagent K, N-ethoxycarbonyl-2-
ethoxy-1,2-dihydroquinoline or the like. For a review of the
methods for acylation, see Methoden der Organischen Chemie
(Houben-Weyl), Vol. XV, part II, page 1 et seq. (1974).
Compounds of formula III include, for example,
proline, hydroxyproline, 4-methylproline, pipecolic acid,
5-hydroxypipecolic acid, azetidine-2-carboxylic acid, their ;~- `
lower alkyl esters and the like. The acylation of such
compounds is described in greater detail below. -
According to a preferred method for producing compounds
of formula I, especially wherein R2 is R5-CO-, an acid or
ester of formula III is coupled with a haloalkanoic acid of
the formula
--7--
(
~1~2;~37
HA135b
(V)
I ~ 11 ,
X-(CH) - CH- COOH ;
~herein X is a halogen, preferably chlorine or bromine. This
can be effected by one of the known procedures in which the acid
IV is activated, prior to reaction with the acid III, involving -
formation of a mixed anhydride, symmetrical anhydride, acid
chloride, active ester, or use of Woodward reagent K, EEDQ
(N ethoxycarbonyl-2-ethoxy-1,2-dihydroxyquinoline) or the
10 like. ;~
The product of this reaction is a compound of the
formula ;~
(X) R3
1 . ,
R R H C - (CH) ~ ~-
X - (CH) CH - CO - N - CH-COR
The product of formula X is subjected to a~displacement ;~
reaction with the anion of a thioacid of the formula `~
(VII) ~ ~;
R2~SH .
yielding a product of the formula ;
(XI) R
13
R Rl H2CI (TH)m
R2- S ~ (CH)n CH - CO - N - CH-COR
When R2 is R5CO, this product can then be converted to
the product
(XII) R3 ~ -~
1 1l H2C (CH)m
HS --(CH) - C~l - CO ~ N CH-COR
-8-
.
, , . .. ~' ' ., ' ' " , . : ' " ' ' '
¢
11~23~7 HA135b
by ammonolysis. When R2 is a protecting group, then the
compound of formula XII can be obtained by"deprotection"
as described above. When R is an ester group (i.e., R
is lower alkoxy), the ester group can be removed, e.g.,
when R is tert. butoxy or tert. amyloxy, by treatment of
the ester of formula XI or XII with trifluoroacetic acid
and anisole to give the corresponding free acid. When other
alkoxy groups are present, alkaline hydrolysis will yield
the corresponding acid.
A variation of this procedure involves the use of
an acrylic acid of the formula
~VI) 14
CH=C-COOH
as starting material. This acrylic acid is first converted to
the acid halide form then made to react with a compound of
.
formula III to obtain a compound o:E the formula
(XIII) ; R3
R4 Rl H21C (l )rn
CH=C - CO- N CH-COR
and this intermediate is subjected to the addition reaction
with the thiol or thioacid VII as described above.
A tosyloxyalkanoic acid of the formula
(XIV)
I 4 11 ~ '
CH3- ~ - S020-(CH)n- CH- COOH
can also be used as the agent to acylate the acid of formula
III, then the acylation product is subjected to the displace-
ment reaction, etc., a~ described above.
The acrylic acid of formula VI can alternatively be
first made to react wi~h the thioacid of formula VII to
_g_ ~,
37
HA135b
obtain a product of the formula
( XV )
14
R2-S-CH-CH-COOH
which is converted to its acid halide, e.g., with thionyl
chloride, then coupled to the compound of formula III and
the same sequence as above then followed.
The acid or ester of formula III can also be acylated
with a "protected" form of a ~-mercaptoalkanoic acid of the
formula
(XVI) 14
R8-s-(cH)n-cH-cooH
wherein R8 is the "protecting" group. Such "protecting" groups
can take the form described above.
Following the acylation, the product can be "deprote~cted"
by one fo the known methods referred to above.
Still another acylating agent can take the form of a ~n
;~ , .
thiolactone, e.g., ~-propiothiolactone, a-methyl-~-propiothio-
lactone or the like.
Additional details of preferred modes of producing ~ `
compounds of this invention can be found in the followiny -
and in the specific examples.
According to a particularly preferred modification,
the acid or ester of formula III is acylated with a halo-
alkanoyl halide of the formula
(XVII) 4 1
. ' ~
X-(CH)n- CH~COX
wherein each X is independently a halogen, preferably chlorine
or ~romine, R1 is hydro(~en, lower alkyl or phenyl-lower alkyl
O
."
,............................................................................ .
37
I~A135b
and n is 0, 1 or 2. This reaction is effected in an alkaline
medium, e.g., dilute alkali metal hydroxide solution, alkali
metal bicarbonate or alkali metal carbonate solution at a
reduced temperature, e.g., about 0 to 15C. The reaction
product is subjected to displacement with the anion of the
thiol or thio acid of the formula VII above, also in alkaline
medium, preferably alkali metal carbonate solution, and then
worked up in conventional manner. The product of this
reaction, wherein R2 of formula I is R5-CO, is converted to
the product wherein R2 is hydrogen by ammonolysis, e.g.,
alcoholic ammonia or concentrated ammonium hydroxide solution,
or alkaline hydrolysis, e.g., with aqueous metal hydroxide.
When an acid of formula III is used as starting material, the
final product obtained as the free carboxylic acid can then be
converted to its ester, for example by esterification with
a diazoalkane, like diazomethane, l-alkyl-3-p-tolyl-triazene,
like l-n-butyl 3-p-tolyltriazene or the like. Treatment of an ~-
ester, preferably the methyl ester, with an alcoholic ammonia
solution, converts the free acid to the amide, i.e., R is NH2.
2~According to another variation, an ester, preferably
the t-butyl ester, of formula III, in an anhydrous medium
such as dichloromethane, tetrahydrofuran, dioxane or the like,
is treated with a thioalkanoic acid of the formula
(XVIII) R
I1 .~.
K2-S-(CH2)n- CH - COOH
in the presence of dicyclohexylcarbodiimide, N,N'-carbonyl-
bisimidazole, ethoxyacetylene, diphenylphosphoryl azide or
si~ilar coupling agents at a temperature in the range of about
0 to 10 C. The ester group (K) can then bc removed, for
.~, --11-- .
3 ~
HA135b
example, by treatment with trifluoroacetic acid and anisole
at about room temperature.
When an ester of formula III (e.g., R is lower
alkoxy, especially, t-butoxy) is acylated with a thiolactone, ~1
e.g., ~-propiothiolactone, a-methyl-~-propiothiolactone or the
like, the reaction can be effected in an anhydrous solvent
like tetrahydrofuran, dioxane, methylene chloride or the
like at about 0 C. to about room temperature. The ester
group can be removed with anisole and trifluoroacetic acid
as described above. M
In similar manner, when R2 is R5-M-C-,-products of
formula I having this substituent are formed by reacting a ~:
compound of formula XII with the halogenated compound
(XIX) M
R5-M-C-X
or alternatively reacting a compound of formula X with an
alkali metal salt ox alkaline earth metal salt of the
formula .~i`-`~-
(XX) ~ M
R5-M-C-S-Me -~
wherein Me represents the alkali metal or alkaline earth me*al.
M
When R2 lS R5-NH-C-, products of formula I having this
substituent aré produced by reacting a compound of formula XII
with the appropriately substituted isocyanate or isothio-
cyanate of the formula - ;~;
, :
(XXI)
R5-N=C=M
Alternatively, the same products can be produced by coupling `~
an acid of the formula
-12-
~2~3~
HAl3Sb
(XXII)
M R . R
1l 14 1l
R5-NH-C-S-(CH)n CH-COOH
with an amino acid of formula III.
Compounds of formula I, wherein R2 is lower alkyl, phenyl,
substituted phenyl, phenyl-lower alkyl, triphenyl-lower alkyl,
lower alkylthiomethyl or phenyl-lower alkylthiomethyl are
produced by reacting a compound of formula XII with the
corresponding halide R2X or by reacting a compound of formula X
l0 with the corresponding thiol R2SH in the same manner as ~s
described above.
When R2 is lower alkanoylamidomethyl, the product of
formula I is produced by condensing a compound of formula XII
with the corresponding hydroxymethyl-lower alkanoylamide of
the formula
(XXIII) lower alkyl-CO-NHCH2OH
in the presence of an acid catalyst like trifIuoroacetic acid.
Products of formula I wherein R2 is R6-S can be ~ -
prepared by any of the known methods for the synthesis of
mixed disulfides, e.g., by the reaction of a compound of
formula(XII)with a thiosulfinate(xxIv), thiosulfonate (XXV),
sulfenyl halide (XXVI), thiosulfate (XXVII) or sulfenyl
thiocyanate (XXVIII) O
(XXIV) R6-S-S-R6 , (XXV) R6-S-S-R6 , (XXVI) R6S-X,
O ' '~ ,',:
(XXVII) R6-S~SO3H/ (XXVIII) R6-S-SCN
In the particular case wherein R7 is
13
IR4 1l fH2 - (CH)n
-S(O) - (CH) -- CH - CO - N CH-CO~,
, -13-
.
~ 2~37 HA135b ~ ; ~
R, Rl, R3 and R4 are the same as the corresponding substituents
in formula I and p is O, the symmetrical disulfides can be
obtained by direct oxidation of a compound of formula XII
with iodine. When p is 1 or 2, such products are obtained
by the stepwise oxidation of the corresponding compound wherein
p is O. Mixed disulfides are obtained by the modification
shown in the examples.
Products of formula I have one or more asymmetric carbons. `;
When Rl, R3 or R4 is other than hydrogen the carbon to which ~-
10 it is attached is asymmetric. These carbon atoms are ~ -
indicated by an asterisk in formula I. The compounds
accordingly exist in stereoisomeric forms or in racemic ~ `
mixtures thereof. All of these are within the scope of
the invention. The above described synthesis can utilize
the racemate or one of the enantiomers as starting material. -
When the race~ic starting material is used in the synthetic
procedure, the stereoisomers~obtained in the~product can be
separated by conventional chromatographic or fractional
crystallization methods. In general, the L-isomer with
respect to the carbon of the amino acid constitutes the
preferred isomeric form.~ Also the D-isomer with respect to
the a-carbon in the acyl side chain (i.e., the carbon
bearing Rl) is preferred.
The compounds of this invention form basic salts
with various inorganic and organis bases which are also ;;
within the scope of the invention. Such salts include
ammonium salts, alkali metal salts like sodium and potassium
salts (which are preferred), alkaline earth metal salts like
the calcium and magnesium salts, salts with organic bases,
e.g., dicyclohexylamine salt, benzathine, N-methyl-D-glucamine,
-14-
.
.
~la2~37 HA135b
hydrabamine salts, salts with amino acids like arginine,
lysine and the like. The non-toxic, physiologically acceptable
salts are preferred, although other salts are also useful,
e.g., in isolating or purifying the product, as illustrated
in the examples in the case of the dicyclohexylamine salt.
The salts are formed in conventional manner by reacting
the free acid form of the product with one or more equivalents
of the appropriate base providing the desired cation in a
solvent or medium in which the salt is insoluble, or in
water and removing the water by freeze drying. By neutralizing
the salt with an insoluble acid like a cation exchange resin
in the hydrogen form (e.g., polystyrene sulfonic acid resin
like Dowex 50) or with an aqueous acid and extraction with an ~ -
organic solvent, e.g., ethyl acetate, dichloromethane or the
like, the free acid form can be obtained, and, if desired,
another salt formed. ~;
;~
., .
; .:,
-15- :
-
:~ :
~2~37
HA135b
Additional experimental details are Eound in tlleexamples which are preferred embodiments and also serve as
models for the preparation of other members of the group. ~,
The compounds of this invention inhibit the conversion
of the decapeptide angiotensin I to ancjiotensin II and
therefore are useful in reducing or relieving angiotensin related
hypertension. The action of the enzyme renin Oll angiotensinogen,
a pseudoglohulin in ~lood plasma, produces angiotensin I.
Angiotensin I is converted by angiotensin converting enzyme ~-
(ACE) to anglotensin II. T~ie latter is an active pressor
substance which has been implicated as the causative -
agent in various forms of hypertension in various mammalian
species, e.g., rats and dogs. The compounds of~this invention ~
intervene in the angiotensin(renin)-~anyiotensi.n I ~angiotensin II ~ ~ -
se~uence by inhlbiting angiotensin converting enzyme and reducing
or eliminating the formation of the pressor substance
angiotensin II. Thus by the administration of a composition
containing one or a cornbination of compounds of fo~mula I
~:
or physiologically acceptable salt thereof, angiotensin
dependent hypert~nsion in the species of mammal suffering
therefrom is alleviated. A single dose, or pre~erably two
: to four divided daily doses, provided on a basis of about 0.1 to
100 mg. per kilogram per day, pre~erably about 1 to 50 mg. per
kilogram per day is appropriate to reduce blood pressure as
indicated in the animal model experiments descri.bed by
S.L. Engel, T. R. Schaeffer, M.H. Waugh and B. Rubin,
Proc. Soc. Exp. Biol. Med. 143, 483 (1973). 'rhe substance
is preferably administered orally, but parenteral routes
such as subcutaneous, intramuscular, intravenous or
-16-
3~
HA135b
intraperitoneal can also be employed.
The compounds of this invention can be utilized to
achieve the reduction of blood pressure by formulating in
compositions SUC}l as tablets, capsules or elixirs for oral
administration or in sterile solutions or suspensions for
parenteral administration. About 10 to 500 rny. of a
- compound or mixture of compounds of formula I or physiologically
acceptable salt is compounded with a physiologically
acceptable vehicle, carrier, excipient, binder, preservative, .
stabilizer, flavor, etc., in a unit dosage form as called
for by accepted pharmaceutical practice. The amount of active -
substance in these compositions or preparations is such that
a suitable dosage in the range indicated is ob~ained.
Illustrative of the adjuvants which may be incorporated ;~
in tablets, capsules and the like are the following: a binder -
such as gum tragacanth, acacla, corn starch or gelatin; an
excipient such as dicalcium phosphate; a disintegrating agent
such as corn starch, potato starch, alginic acid and the like;
a lubricant such as magnesium stearate; a sweetening agent
sucll as sucrose, lactose or saccharin; a flavoring agent such
as peppermint, oil of wintergreen or cherry. ~hcn the dosa~e
unit form is a capsule, it may contain in addition ~o rnaterials ;~
of the above type a liquid carrier such as a fatty oil. Various
other materials may be presen~ as coatings or to otherwisc
modi~y the physical form of the dosage unit. For instance,
ta~lets may be coated with shellac, sugar or both. ~ syrup
or elixir may contain the active compound, sucrose as a
sweetening agent, methyl and propyl parabens as preservatives,
a dye and a flavoring such as cherry or oranye flavor.
Sterile compositions for injection Call bc ~ormula~ed
,, ~' '
-17-
.
'~ .
11~ Z33 7 IlAl3sb
according to conventional pharmaceutical practice by
dissolving or suspending the active substance in a vehicle
such as water for injection, a naturally occurring vegetable
oil like sesame oil, coconut oil, peanut oil, cottonseed ~ , -
oil, etc., or a synthetic fatty vehicle like ethyl oleate or
the like. Buffers, preservatives, antioxidallts and tlle like
can be incorporated as required.
The following examples are illustrative of the invention `~
and constitute especially preferred embodiments. A11 tempera~
tures are in degrees celsius.
:
- -18-
}3~
~A135b
Exam~le 1
1-(2-senzo lthioacetyl)-L-Proli.ne
Y
L-Proline (5.75 g.) is dissolved in N sodium hydroxide
(S0 ml.) and the solution is chilled in an ice-water bath.
Sodium hydroxide 2N (26 ml.) and chloroacetyl cllloride (5.65 g.)
are added andthe mixture is stirred viyorously at room
temperature for three hours. ~ suspension o~ thiobenzoic acid
(7.5 g.) and potassium carbonate (4.8 g. ) in water (50 ml.)
is added. After 18 hours stirring at room temperature, the
reaction mixture is acidified and extracted with ethyl acetate.
The ethyl acetate layer is washed witll water, dried over
magnesium sul~ate and concentrated to dryness il~ vacuo. lhe
residue (14.6 g.) is dissolved in ethyl acetate (150 ml.) and
dicyclohexylamine (11 ml.) is added. The crystals are filtered
and recrystallized from ethyl acetate, yield 5.7 g. m.p.
151-152 . To convert tlle salt to the acid, the crystals are
dissolved in a mixture of 5~ aqueous potassium bisulfate
(100 ml.) and ethyl acetate (300 ml ). ~rhe oryanic phase is
washed once with ~ater, dried over magnesium sulfate and
concentrated to dryness in vacuo, yield 3.45 g.
Example 2
1-(2-Mercaptoacetyl)-L~Proline ~ -
.
1-(2-Benzoylthioacetyl)-L-~roline (3.4 g.) is dissolved
in a mixture of water (10.5 ml.) and concentrated a~NmOnia (6.4 ml.
After one hour, the reaction mixture is diluted with water `~
and filtered. The filtrate is extracted with ethyl acetate
and then acidified with concentrated hydrochloric acid, -
saturated with sodium chloride and extracted ~wice with ethyl
acetate. The ethyl acetate extracts are washed with saturated ~;~
sodium chloride and concentrated to dryness, yield 1.5 cJ.
--19--
, .
.
~&23~
HA135b
The product, 1-(2-rnercaptoacetyl)-L-proline is crys~allized
from ethyl acetate (m.p. 133-13
Example 3
:
1-(2-Benzoylthioacctyl)-L-Proline Methyl Ester
,,
1-(2-Benzoylthioacetyl)-L-proline obtained in
Example 1, is dissolved in methanol and an ethereal solution
of diazomethane is added until there is a persistent yellow
color. After 15 minutes, a few drops of acetic acid are
added and the solvent is removed in vacuo to obtain 1-(2-
benzoylthioacetyl)-L-proline methyl ester.
Example 4
1-(2-Mercaptoacetyl)-L-Proline ~nide
The product of Example 3 is dissolved in 10s methanolic
ammonia and the solution is stored at room temperature in a ~ ;
.
`:
pressure bottle. When thin layer chromatographic analysis ~ ~
indicates that the two ester functions have been ammonolyzed, ~`
the reaction mixture is concentrated to dryness to obtain
1-(2-mercaptoacetyl)-L-proline amide.
~ e 5
1-(2-Benzoyltllioacetyl)-L-IIydroxypro1ino
By substituting L-hydroxyproline for tile L-proline
in the procedure of Example 1, 1-(2-benzoylthioacetyl)-L-
hydroxyproline is obtained.
~ 6
1-(2-Mercaptoacetyl)-L-I~ydroxyproline
By treating the product o~ Example S with ammonia as
in Example 2, 1-(-mercaptoacetyl)-L-hydroxyproline is obtained. '~
~xample 7
.
1- (2-Bc~1l%0ylthio.lccty~ J-A~ct:idillc-2-c~ J_)_yl i.C /~ci.cl
~y substituti.ncJ L-a~etidinc-~-c~oxylic acid or the
,
-20-
3~
~A~13~)D
proline in the ~rocedure of ~ample 1, 1-(2-benzoyl-
thioacetyl)-L-azetidine--2-carboxylic acid is obtained.
~xample 8
,
1-(2-Mercaptoacetyl)-L-Azetidine-2-Carboxylic Acid
By treating the product of ~xample 7 with ammonia
as in Example 2, 1-(2-mercaptoacetyl)-L-azetidine-2-carboxylic
acid is obtained.
- Example 9
1-(2-Ben~oylthioacetyl)-L-pipecolic Acid
,,
By substituting L-pipecolic acid Eor the L-proline
in the procedure of Example 1, 1-(2-~enzoylthioacetyl)-L-
pipecolic acid i5 obtained.
~xample 10
.
1-(2-Mercaptoacetyl)-L-Pipecolic ~cid
By treating the product of Example 9 with ammonia as
,
in Example 2, 1-(2-mercaptoacetyl)-L-pipecolic acid is ;~
obtained,
~xample 11
1-(2-Benzoyltlliopropanoyl)~L-Proline
L-Proline (5.75 g. ) is dissolved in aqueous N sodium
hydroxide (50 ml.) and the solution is chilled in an ice
bath with stirring. 2N sodium hydroxide (25 ml.) and 2-bromo-
propionyl chloride (R,57 g.) are added in that order and
the mixture is removed from the ice bath and stirred at room
temperature for one hour. A mixture of thiobenzoic acid ;~
(7.5 g.) and potassium carbonate (4.8 g.) in water (50 ml.)
is added and the mixture is stirred overnight at room
temperature. After acidification with concentrated hydro-
chloric acid, the aqueous solution is extracted with etl-yl
acetate and the organic phase is washed with water, dried and
.
-21-
~Z~37 ~ ~
HA135b
concentrated to dr~ness. The residue ~14.7 ~.) is chromato~raphed
on a column of 440 g. of silica gel with a mixture of
benzene~acetic acid (7:1). The fractions containing the
desired material are pooled, concentrated to dryness, and the
residue is preci~itated twice with ether-l~exane and converte~
~o a di.cyclohexylamine salt in ether-hexane, yield 9.4 y.
m.p.,(142) 148-156 .The dicyclohexylamine salt is converted back to
the acid as in Example 1, yield 5.7 g.
~ E~ _12
1-(2-Mercaptopropanoyl)-L-Proline
1-(2-~enzoylthiopropan~l)-L-proline (5.7 ~.) is
dissolved in a mixture of water (12 ml.) and concentrated
ammonium hydroxide (9 ml.) with stirring. A~ter one llour,
the mixture is diluted with water (10 ml.) and filtered.
The filtrate is extracted twice wlth ethyl ace~tate, concentrated
to one-third of the original volume, acidified with concentrated
hydrochloric acid and extracted with ethyl acetate. The
organic phase is washed with saturated sodium cllloride, ,~
dried and concentrated to dryness ln vacuo. The residue,
1-(2-mercapto~ropanoyl)-L-proline, is crystallized from
ethyl acetate-hexane, yield 3 g.,m.p. (105) 116-120 .
~xample 13
1-(3-Benzoyl1:11iopropanoyl)-L-Proline
_
L-Proline (5.75 g.) is dissolved in normal sodium
hydroxide (50 ml.) and the solution is chilled in an ice bath.
3-Bromopropionyl chloride (8.5 g.) and 2N sodium hydroxide
(27 ml.) are added and the mixture is stirred ~or 10 minutes
in the ice batll and three hours at room temperaturc. A
suspension of ~hio~ellzoic acid (7.5 ~.) and po~assium carbonate
(4.5 ~.) in water ( 50 ml.) is added and tlle mixture is stirred
-22-
1~2~3~
~A1~5b
'-or 18 hours at room ~emperature. After acidifica~ion ~ith
concentrated hydrochloric acid, the aqueous pJlase is
extracted twice ~ith ethyl acetate. 'rhe organic l~yers
are dried over magnesium sulfate and concentratecl to dryness
in vacuo to obtain 1-(3-benzoylthlopropanoyl)-L-proLine
yield 7.1 g., m.p. 101-102 ~ethyl acetate-hexane).
Example 1
L-Proline tert.-butyl ester
~ ~_ . .
L-Proline (230 g.) is dissolved in a mixture of
water (1 1.) and 5 N sodium hydroxide (400 ml.). The solution
is chilled in an ice bath, and under vigorous stirring, S N
sodium hydroxide (460 ml.) and benzyloxycarbonyl cllloride
(340 m'.) are added in flve equal aliquots during a half
hour period. ~fter one llour stirring at room temperature, the
mixture is extracted twice with ether and acidified with
concentrated hydrocllloric acid. The precipitate is filtercd
and dried. Yield 442 g. m.p. 78-80.
Tlle benzyloxycarbonyl-L-proline thus obtalned
(180 g.) is dissolved in a mixture of dichlorornethane
(300 ml.),liquid isobutylene (800 ml.) and concentrated ~;~
sulfurîc acid (7.2 ml.). The solution is shaken in a -
pressure bottle for 72 hours. The pressure is released,
the isobutylene is allowed to evaporate and the solution is
"ashed ~"ith 5~ sodium carbonate, water, dried over magnesium
sulfate and concentrated to dryness in vacuo,to obtain benzyloxy~
carbonyl-L-proline tert.butyl ester, yield 20~ g.
~enzyloxycarbonyl-L~proline tert.butyl ester (205 g.)
is dissolved in absolute ethanol (1.2 1) and hydrogenated at
normal pressure with 10~ Pd on carbon (10 g.) until only a
trace of carbon dioxide is observed in the hydrogcn exit yas
-23-
~3~Z~37
HA135b
(24 ~lours)~ The catalyst ls Eiltered off and ~he filtrate
is concentrated _ vacuo at 30 mm. ~Ig. The residue is
distilled in vacuo, to obtain L-proline tert.butyl ester,
b.p. 50-51.
lmm
~ xample lS
]-(3-Acet lthiopropanoyl)-L-Prolinc ter~-butyl ~ster
L-Proline tert-butyl ester (5.13 g.) is dissolved in
dichloromethane (40 ml.) and the solution is chilled in an
ice-water bath. A solution of dicyclohexylcarbodiimide
(6.18 g.) in dichloromethane (20 ml.) is added followed
immediately by 3-acetylthiopropionic acid (4.45 y.). After
15 minutes stirring in the ice-water bath and 16 hours at
room temperature, the precipitate is filtered off and the
filtrate is concentrated to dryness in vacuo. The residue is
dissolved in ethyl acetate and washed neutral. The organic
layer is dried over magnesium sulfate and concentrated to
dryness in vacuo to obtain 9.8 g. of l-(3-acetylthiol?ro~anoyl)-L~
proline tert-but~l ester.
~xample 16
l-(3-~cet~lthio~ropanoyl)-L-Proline
1-(3-Acetylthiopropanoyl)-L-proline-t-butyl ester
(4.7 g.) is dissolved in a mixture of anisole (34 ml.) and
trifluoroacetic acid (68 ml.l and the mixture is kep~ at
room temperature for one hour. The solvents are removed
in vacuo and the residue is precipitated from ether-hexane
several times. The residue (3.5 g.) is dissolved in
acetonitrile (25 ml.) and dicyclohexylamine (2.8 ml.) is
added. The crystalline salt is filtered and recrystallized
from isopropanol. Yield 3.8 g.. m.p. 1?6-177 . The salt
is reconverted to 1-(3-acetylthiopropanoyl)-L-proline as in
-24-
~1~2~37
HA135b
~xample 1, yield 1.2S g., m.p. 8.9-90 (ethyl acetate-llexane).
Examplc 17
1-(3-Mercaptopropanoyl)-L-proline tert-butyl ster
To a solution of L-proline tert-butyl ester (3.42 g.)
in dry tetrahydrofuran (10 ml~) chilled in an ice ~ath,
propiothiolactone (1.7G g.) is added. ~fter 5 minutes storage in
- the ice bath and three hours at room temperature/ the reaction
mixture is diluted with ethyl acetate (200 ml.) and washed
with 5% potassium bisulfate, and water. The organic layer
is dried over magnesium sulfate and concentrated to dryness ln
vacuo. The residue 1-(3-mercaptopropanoyl)-L-proline tert-
butyl ester is crystallized ~rom ether-hexane, yield 3.7 g , , ~;
m.p. 57-58 -
Example 18
1-(3-Mercaptopropanoyl)-L-Proline
Procedure
1-(3 Benzoylthiopropanoyl)-:L~proline (4.9 g.) is
dissolved in a mixture of water (8 ml.) and concentrated ammonium
hydroxide (5.6 ml.) and the solution is stored with stirring
~0 under argon for one hour. The reaction mixture is diluted
with water, filtered, and the filtrate is extracted with
ethyl acetate. The aqueous phase is acidified with concentrated
hydxochloric acid, saturated with sodium chloride and extracted
with ethyl acetate. The organic layers are washed with
saturated sodium chloride, dried over magnesium sulfate, and
concentrated to dryness in vacuo. The residue,l-(3-mercapto-
propanoyl.)-L-proline, is crystallized from ethyl acetate
hexane, yield 2.5 ~., m.p. 68-70 .
Procedure B
.
1-(3-~cetylthiopropanoyl)-L-proline (0.8 g.) is dissolved
( ~
~l~Æ;~37
HA135b
in 5. S N me~hanolic ammonia (5 ml.) and the solu~ion ~eL~t
under argon at room temperature. A~ter 2 hours th~ solvent i5
removed in vacuo, the residue is dissolved in water and applied
to an ion exchange column on the H cycle~Dowex 50(Analytical
grade)]and eluted with water. The ~ractiolls tllat ~ive thiol
positive reaction are pooled and concentrated to dryness,
yield 0~6 g. This product is crystallized from ethyl acetate-
hexane as in Procedure A to obtain 1-(3-mercaptopropanoyl)-L-
proline.
Procedure C
~ .
1-(3-Mercaptopropanoyl)-L-proline t-b~tyl ester (2.3 g.)
is dissolved in a mixture o anisole (Z0 ml.) and trifluoro-
acetic acid (45 ml.). After one hour storage at room temperature
under argon, the reaction mixture is concentrated to dryness
in vacuo and the residue precipitated ~rom e~hyl acetate-
hexane several times. l`he residue (l.9 y.) ~is dissolved in
ethyl acetate (30 ml.)~and dicyclohexylamine (1.85 Ml.) is
added. The crystalline salt is ~iltered and recrystallized
from isopropanol, yield 2 g. m.p. 187~188.
The salt is converted to the acid as in ExampIe 1,
yield 1.3 g. The product is crystallized from ethyl acetate
hexane as in Procedure A.
Salts
Sodium ;
1-(3-Mercaptopropanoyl)-L-proline (500 my.) is dissolved ~
in a mixture o~ water (2.5 ml.) and N sodium hydroxidc (2.5 ml.). ~ ;
The solution is freeze dried to obtain tl~e sodium salt.
Magnesium
1-(3-Mercaptopropanoyl)-L-proline (500 mg.),
magnesium oxide (49.5 my.), and i~ater (10 ml.) are stirred
-26-
~Z337
HA135b
~ith slight heatin~ until complete solution is obtailled~
Then the solvent is removed by freeze dryiny to obtain the
magnesium salt.
Calcium
1-(3-Mercaptopropanoyl)-2-proline (500 mg.) is ;
dissolved in a mixture o~ calciurn hydroxide (91 mc;.) and
water (lO ml.) and the solution is freeze dried to obtain
the c~lciurn salt.
Potassium ,~
l-(3-Mercaptopropanoyl)-L-proline(500 mg.) is
dissolved in a mixture of potassium bicarbonate (246 mg.)
and water (lO ml.) and freeze dried to obtain the potassium -
salt.
N-~ethyl-D-Glucamine
: .
l-(3-Mercaptopropanoyl)-L-proline (500 mg.) and
N-methyl-D-glucamine (480 mg.)~are dissolved in water (l~ ml.)
and freeze dried to obtain the N-methyl-D-glucamlne salt.
Example l9
1-(3-Mercaptopropanoyl)-L-Hydroxyprolinc
sy substituting L-hydroxyproline for the L-proline in
the procedure of Exarnple ll and then treating the product
by Procedure A of Example 18, l-(3-benzoylthi~o~ropanoyl)-L-
hydroxyproline and l-(3-mercaptopropanoyl)-L-hydroxyproline
respectively, are obtained.
Example 20
l-(3-Merc~ptopropanoyl)-L-Azetidine-2-Carboxylic Acid
8y su~stituting L-azetidine-2-car~oxylic acid tert-
butyl ester (prepared by substitutiny L-aze~i.dine-2-
carboxylic acid ~or the proline in ~xample 14) ~or tlle L-
proline tert-~utyl ester in the procedulc oE ~xamL~le 15,
-~7- ;;
~Z;~37
HAl35b
treating the product as in ~xample 16 and the l-(3-acetyl-
thiopropanoyl)-L-azetidine-2-carboxylic acid tllUs obtained by
Procedure B of Example 18, 1-(3-acetylthiopropalloyl)-L-
azetidine-2-carboxylic acid tert-butyl ester and 1-(3-mercapto-
propanoyl)-L-azetidine-2-carboxylic acid, respectively,
are obtained.
Exam~
1-(3-Mercaptopropanoyl~-L-Pipecolic ~cid
By substituting L-pipecolic acid tert-butyl ester
(prepared by substituting L-pipecolic acid for the L-proline
in Example 14) for the L-proline tert-butyl ester in the
procedure of ~xample 15 and ~reating the product by Procedure C
of Example 18, l-~3-mercaptopropanoyl)-L-pipecolic acid tert-
butyl ester and l-(3-mercaptopropanoyl)-L-pipecolic acid,
respectively, are obtained.
,~
Example 22
1-(3-Mercaptopropanoyl)-4-Methyl-L-Proline ~ ~
sy substituting 4-methyl-L-proline for L-proline ~ -
in the procedure of Example 13 and then treating the product
20 by Procedure A of Ex~lple 18, l-(3-benzoyltlliopropanoyl)-
4-methyl-L-proline and 1-(3-mercaptopropanoyl)-4-me~llyl-L-
proline, are obtained.
~xample 23
1-(3-Mercaptopropanoyl)~5-~lydroxy-L-Pipccolic ~cid
By substituting 5-hydroxy~ -pipecolic acid for L~
proline in the procedure of Example 13 and then treating the
product by the Procedure A of Example 18, l-(3~benzoyl- ;
thiopropanoyl)-5-hydroxy-L-pipecolic, and 1-(3-mercapto-
propanoyl)-5-hydroxy-L-pipccolic acid are obtained.
-28-
3~
HA135b
_:~an~ple 21 ,~
_-(3-"~~ca~tol~rol~a.~Gyl)-D-l'roline ~;
.
Ey substitutins D-proline for L-proline in the procedure,
of Ex~rr.?le 13 and then treating the produc-t by Procedure A of
E~;arrp'e 18, 1- (3-benzoylthiopropanoyl)-D-prolille and 1- (3-
r-,e-ca?topropanoyl)-D-proline, m.p. 68-70, are obtained. ~,
Examr~le 25 ''~'
ee-yl.hio-2~ ethyl3ropanoic Acid ~ ~
, :-
~. rnix~ure of~ thioacetic acid (50 g.) and methacrylic '
acid (40.7 g.~ is heated on the steam bath for one hour and
~hen sto.ed a~ room temperature for 18 hours. After confirming
by nm~ s?eetroscopy that complete reaction of the methacrylic
~cid :~as b2en ,achieved, the reaction mixture is distilled ~ ~
~n va-uo and ~he desired 3-aeetylthio-2-methylpropanoic acicl ~ .
~s se?arzt~d in ~he fraction with boiling point 128.5 -131
(2.6 ;;ur.Hg.), ~ield 64 g.
E,~aml~le 2'6~
3-Benzoylthio-2-~1ethylpropanoic l~cid
3y sustituting thiobenzoie aeid for the ~hioacetie
acicl in the proceclure of Example'2s, 3-benzoylthio-2-
;~ethylpropanoic acid is obtained.
~xample 27
3-Phen~lace'~yltllio-2-Methylpropanoic ~cid
3y suJ~stituting thiophenylacetic acid for the ~'
';-.ioecetie aeid in ~he procedure of Exarnple 25, 3-phenyl-
~ce~yl t:~io-2~me~hylpropanoic acid is obtained.
_~ample 28
1-(3-~ce'ylthio-2-1rethylpro~ano l)-L-Prolinc tert-butyl ~ster
. . ~ Y - , :
1-Droline l:ert-butyl esker (5.1,c,~.) is dissolved in
~_c;~'o-omet;~ane (~,0 ml.) ancl the solution stirred and chillcd
--29--
'' . , '' , :~ ~ , :
3 ~
HA135b
in an ice bath. DicyclohexylcarbodiilTIide (G.2 y.) dissolved
in dichloromethane (15 ml.) is added followed immediately
by a solution of 3-acetylthio-2-methylpropanoic acid (4.9 g.)
in dichloromethane (5 ml.). After lS minutes stirring in
the ice batl- and 16 hours at room temperature, the precipitate
is filtered off and the filtrate is concentrated to dryness
in vacuo. The residue is dissolved in ethyl acetate and washed ;'
neutral. The organic phase is dried over maynesium sulfate
and concentrated to dryness in vacuo. The residue 1-(3-
acetylthio-2-methylpropanoyl)-L-proline tert-butyl ester is
purified by column chromatography (silica ~el-chloroorm),
~ield 7.9 g. ,
xample 29
1-(3-l~cetylthio-2-methylpropanoyl)-L-Proline
Procedure
The 1-(3-acetylthio-2-methyl~propanoyl)-L-prollne ,
tert-butyl ester of Example 28 ~7.8 g.) is dissolved in a
mixture of anisole (55 ml.3 and trifluoroacetic acid (110 ml.).
After one hour storage at room temperature the solvent is
removed in vacuo and the residue is precipitated several
- -
times from ether-hexane. The residue (6.8 g.) is dissolved
in acetonltrile (40 ml.) and dicyclohexylamine (4.5 ml.) is
added. The crystalline salt lS boiled Witll fresh'acctonitrile
(100 ml.), chilled to room temperature and filtcred, yield
3.8 g., m.p. (165) 187-188 . This material is recrystallized ,~
from isopropanol, [~D-67 (C 1.4, EtO~). The crystalline
dicyclohexylamine salt is suspended in a mixture of 5~ aqueous
potassium bisulfate and ethyl acetate. The oryanic pllase is
washed with water and concentrated to dryncss. The residue is
crystallized ~rom etl-yl ace~atc-hexanc ~o yield the 1-(3-acctyl-
-30-
,;
233~7
HA135b
thio-2-D methylpropanoyl-L~proline,m.p.83-85 [a]~ -162(c,1.7,~tOII)
Procedure B
3-Acetylthio-2-methylpropanoic acid (8.1 y.) and
thionyl chloride (7 g.) are mixed and the suspension is stirred
for 16 hours at room temperature. ~rhe reaction mixture is
concentrated to dryness and distilled in vacuo (b.p. 80 ). ; ~ ,
^This 3-acetylthio-2-methylpropanoic acid chloride (5.4 g.)
and 2N sodium hydroxide (15 ml.) are added to a solution of
L-proline (3.95 g.) in normal sodium hydroxide (30 ml.)
chilled in an ice water bath~ After 3 hours stirring at
room temperature, the mixture is extracted with ether, the
aqueous phase is acidified and extracted with ethyl acetate.
The organic phase is dried over magnesium sulfate and concentrated
to dryness to obtain 1-(3-acetylthio-2-DL-methylpropanoyl-L-
proline.
Procedure C
Methacryloyl chloride (4.16 g.) is added to a solution ~ ;
or L-proline (3.45 g.) in a mixture o water (100 ml.) and
sodium blcarbonate (12 g.) chilled in an ice water bath, with
vigorous stirring. When the addition is completed, the mixture
is stirred at room temperature for two hours, and then extracted
with ether. The aqueous phase is acidified with N hydrochloric ;~`
acid and extracted with ethyl acetate. The organic phase is
concentrated to dryness in vacuo, the residue is mixed with
thiolacetic acid (3.5 g.), a few crystals of azobisisobuty-
ronitrile are added and the mixture is heated on the steam bath
for two hours. The reaetion mixture is dlssolved in benzene-
acetie aeid (75:25), and applied to a eolumn of silica gel.
Elution witll t~le same solvent mixture yields the 1-(3-acetylthio-
2-DL-methylurop~lloyl)~ proline.
-31-
. .
HA135b
I~;amplé ~0
1-(3-Bellzoyltllio~2-metllylpropanoyl)-L-proliJle tert-butyl ~ster
By substituting 3-benzoylthio-2-methylpropanoic acid for
the 3-acetylthio~2-methylpropanoic acid in the procedure
of Exam~le 28, 1-(3-benzoylthio-2-methylpropanoyl)-L-proline
tert.butyl ester is obtained.
~xample 31
1-(3-Phenylacetylthio-2-methylpropanoyl)-L-PLoline tert-butyl ~ster
By substituting 3-phenylacetyltllio-2-methylpropanoic
acid for the 3-acetylthio-2-methylpropanoic acid in the
procedure of ~xample 28, 1-(3-phenylacetylthio-2-methylpropanoyl)~
L-proline tert butyl ester is obtalned.
:~amplc 32
1-(3-Benzoylthio-2-methylpropanoyl)-L-proline
.. . . .
By substituting 1-(3-benzoylthio-2-methylpropanoyl)-
L-proline tert-butyl ester ~or the 1-(3-acetylthio)-2-
methylpropanoyl)-l-proline tert-butyl ester in Procedure A
of Example 29, 1-(3-benzoylthio-2-methylpropanoyl)-L- ~-~
proline is obtained.
~ample 33
1-(3-Phenylacetyltllio-2-methylpropanoyl)-L-prolille
. ~
By substituting 1-(3-phenylacetylthio-2-metllylpropanoyl)-
L-proline tert-butyl ester for 1-(3-acetylthio-2-metl~ylpropanoyl)~
L-proline tert-butyl ester in Procedure A of Lxample 29,
1-(3-phenylacetylthio-2-methylpropanoyl)-L-proline is obtained.
1-(3-Mercapto-2-D~metl~ ropanoyl ? -L-Proline
1-(3-Mercapto-2-methylpropanoyl)-L-proline is
obtained by treating the product of each o~ ~xamples 29, 32 and
33 as follows:
-32-
.. ~ . . .
, ~
. , ' ' , ,
37
HA135b
'rlle thioestcr (0.85 cj.) i5 dissolved in 5.5 N
methanolic ammonia and the solution is kept at room temperature
for 2 hours. The solvent is removed ln vacuo and the residue
is dissolved ln water, applied to a ion exchan~e column on
the H cycle (Dowe~ 50, analytical yrade) and eluted with
water. The fractions tllat yive positive thiol reaction are
pooled and freeze dried. The residue is crystallized from
ethyl acetate-hexane, yield 0.3 g. The 1-(3-mercapto-2~-
methylpropanoyl-L-proline has m.p. 103-104 , [~] -131
(C,2,EtOH).
~ xample 35
1-(3-~cetylthio-2-methylpropanoyl-)-L-proline-Mctllyl ~ster
-: :
1-(3-Acetylthio-2-methylpropanoyl)-L-proline is
reacted with an ethereal solution of diazomethane accordinc
to the procedure described in ~xample 3 to obtain 1-(3-ace~yl-
thio-2-methylpropanoyl)-L-proline methyl ester.
xample 36
1-(3-Mercapto-2-methylpropanoyl)-L-Proline amide
By substituting 1-(3-acetylthio-2-metllylpropanoyl)-
L-proline methyl ester in the procedure of Example 4, 1-(3-
mercapto-2-methylproyanoyl)-L-proline amide is obtained.
xample 37
3-~cetylthio-2-Benzylpropalloic ~cid
By substituting 2-benzylacrylic acid for ~he
methacrylic acid in the procedure of Example 25, 3-acetyl-
thio-2-benzylpropanoic acid is obtained.
Examyle 38
1-(3-~cetyltllio-2-benzylpropalloyl)-L-Prolinc tert-butyl Ester
By substitutiny 3-acetylthio-2-benzylpropanoic acid ~or
the 3-acetylthio-2-methylproyanoic acid in tlle procedure of
-33-
. : ~
37
HA135b
~xample 22, 1-(3-acetylthio-2-benzylpropanoyl)-L-proline
tert-butyl ester is obtained.
Example 39
1-(3-~cetylthio-2-benzylpropan ~ l)-L-Proline
The product of Example 38 is substituted for the 1-(3-
acetylthio-2-methylpropanoyl-L-proline tert-butyl ester in
the Procedure A of Example 29 to obtain 1-(3-acetylthio-2-
benzylpropanoyl)-L-proline.
Example 40
,
10 1-(3-Mercapto-2-benzylpropanoyl)-L-Proline : -~
1-(3-Acetylthio-2-benzylpropanoyl)-L-proline is treated
with methanolic ammonia according to the procedure of Example
34 to obtain 1-(3-mercapto-2-benzylpropanoyI)-L-proline as an
oil, Rf = 0.47 (silica gel, benzene-acetic acid (75:25).
Example 41
1-(3-Mercapto-2-methylpropanoyl)-L-Hydroxy Proline
By substituting L-hydroxy proline tert-butyl ester in
the procedure of Example 2%, treating the product according
to Procedure A of Example 29 and then continuing as in Example ~ ;
34, l-(3-acetylthio-2-methylpropanoyl)-L-hydroxyproline
tert-butyl ester, l-(3-acetylthio-2-methy:lpropanoyl)-L-
hydroxyproline and l-(3-mercapto-2-methylpropanoyl)-L-
hydroxyproline, respectivelyl are obtained~
Example 42 ~:
1-(3-Mercapto~2-methylpropanoyl)-L-Azetidine-2-Carboxylic Acid
By substituting L-azetidine-2-carboxylic acid tert-
butyl ester in the procedure of Example 28, treating the product
according to the Procedure A of Example 29 and then continuing as
.
-34-
3;~7 ``
HA135b
in Exam~le 34, 1-(3-acetylthio-2-mctllylplopanoyl)-L-aze~idine-
2-carboxylic acid tert-butyl ester, 1,3-acetylthio 2-methyl-
propanoyl)-L-azetidine-2-carboxylic acid and 1-(3-mercapto-
2-methylpropanoyl-L-azetidine-2-carboxylic acid are obtained.
.
~ample 43
:
1-(3-~lerca~to-2-methylpropano~l)-L-Pipecolic ~cid
By substituting L-pipecolic acid in the procedure of
Example 28,treating the product accordiny to Procedure A of
Example 29and then continuing as in ~xamplc 34 , 1-(3~acetyl- ~ ~?
thio-2-methylpropanoyl)-L-pipecolic acid tert-butyl ester,
1-(3-acetylthio-2-methylpropanoyl)-L-pipecolic acid and 1-(3-
mercapto-2-methylpropanoyl)-L-pipecolic acid, respectively,
are obtained.
Example 44
1-(4-BenzoYltlliobutanoyl)-L-Proline
To a solution of L-proline [2.~8 g.) ill nornlal sodium
hydroxide (25 ml.) chilled in an ice bath, 2N sodium hydroxide
(12.5 ml.) and 4-chlorobutyryl chloride (3.5 g.) are added.
The reaction mixture is stirred at room temperature for 3. 5
hours and a suspension of thiobenzoic acid (3.75 y.) and
potassium carbonate (2.4 g.) in water (25 ml.) is added. ~fter
ovcrnight stirring at room temperature, the reaction mixture
is acidified with concentrated hydrocllloric acid and e~tracted -~ -
with ethyl acetate. The oryanic layer is dried over magnesium
sulfate and concentrated to drynes~ in vacuo. The residue
is chromato~raphed on a column of silica ~el witll ~enzene- ;~ ;
acetic acid ~7:1). The fractions contailling the desired material
are pooled and concentrated to dryness, yicld 1.35 ~. ~ small
aliquot of this material is dissolved in ethyl accta~e and
dicyclollexylamine is added until l~tl 8-10 (on a we~ plllapcr).
-35-
.,
.,
~2337
HA135b
The dicyclohexylamine salt crystallizes out, in~nediately, m.p.
159-161.
`xample 45
1-(4-McL-car~tobutanoyl)-L-Proline
. ,
1-(4-~enzylt}liobutanoyl)-L-prolillc (1.08 g.) is
dissolved in a mixture of water (4 ml.) and concentrated
aMmonia (2.7 ml.). Ater one hour stirrin~J at room tempera-
ture, the mixture is diluted with water, filtered, extracted with
ethyl acetate, and the aqueous phase was concentrated in vacuo.
This ammonium salt of 1-(4-mercaptobutanoyl)-L-~roline is
purified by ion exchange chromatography on a column of dietllyl-
aminoethyl-Sephadex(cross linked dex-tran) witll a ~radient
Qf ammonium bicarbonate, yield 0.7 g. Tl-e ammonium sal-t is
dissolved ~n water (2 ml.~ and applled to a column of
Dowex 50 sulfonic acid resin analytical grade ~n the
hydrogen form, and the free acid is eluted with water. The
fractions containing the desired material (sulfllydryl reacJent and
carboxyl reagent positive) are pooled and freeze dried
ko obtain l-(4-mercaptobutanoyl)-L-proline. '~hc dicyclo-
hexyl ammonium salt is produced by the proceduxe of ~xample 44,
m.p. 157-158.
~xample 4
4-3romo-2-Methylbutanoic Acid
~: ,
Ethyl-4-bromo-2-methylbutanoate [G. Jones and J. Wood,
Tetrahedron, 21, 2961 (1965)] (1.04 g.) is dissolved in
dichloromethane (50 ml.) and cooled to -10 . ~ 1 M solution - -
of boron tribromide in dichloromethane 150 ml.) is a~ded
dropwise with stirring and the stirring is continued ~or
30 1 hour ~t -10 and 2 hours a~ 25 . The reaction is termiJlated
- -36-
1~2337
HA135,b ,
by the careful addition of watcr. The lay~rs are separated
and the organic phase is washed ~ith water, ~ried and concen-
trated to dryness to obtain 4-bromo-2-methylbutanoic acid.
Example 47
1-(4-Bcnzoyl~llio-2-metllylbutal-oyl)-L-Prolinc -~
a) 4-Bromo-2-methylbutanoic acid (8 c~.) and tllionyl chloride
(7 g.) are mixed and the mixture is stirred for lG llours at room
temperature. Tl-e reaction mixture is concentrated to dryness
and distilled in vacuo.
' :
b) To a solution of L-proline (2.88 g.) in normal sodium
hydroxide (25 ml.) chilled in an ice bath, 2N sodium hydroxide
(12.5 ml.) and the 4-bromo-2-methylbutanoic acid chloridc ; ~
~ ~ ,
obtained in part (a) (3.9 g.) are added. The reaction ~ '~
mixture is stirred at room teni`perature ~or 3.5 hours and a
suspension of thiobenzoic acid (3.75 g.) and potassium
carbonate (2.4 g.) in ~later (25 ml.) is added. AEter overnight
stirring at room temperature, the reaction mixture is acidified
with concentrated hydrochloric acid and extracted with ethyl -'~
acetate. The organic layer is dried ,over magnesium sulate , ,
and concentrated to dryness in vacuo. 'rlle resi~ue is , ; '-
chromatographed on a column of silica gel with ben~ e-acotic
acid (7:1). The fractions containing the desire~ pro~uct,
1-(4-benzoylthio-2-methylbutanoyl)-L-proline are pooled
and concentrated to dryness in vacuo. ,` ` ~,
E~ample 48
1-(4-~lcrcapto-2-methylbutanoyl)-L-proline
,
By substituting 1-(4-benzoylthio-2-metllylbutanoyl)- :~
L-proline for the 1-(4-benzoylthiobutalloyl)-L,-proline in
the proccdure o~ Exampl~ 45, 1-(4-mercapto-2-lnetllylbutanoyl)-
L-proline is obtained.
-37-
~2;~37
HA135b
Example 49
4-Bromo-2-benzyl~utanoic acid
By substituting ethyl-4-bromo-2-benzylbutanoa-te
[prepared by the procedure of G. Jones and J. ~ood [Tetrahedron,
21, 296,1 (1965) starting with diethylbenzylmalonate'Jl or
_ the ethyl-4-bromo-2-methylbutanoate in the procedure of
Example 46, 4-bromo-2-benzylbutanoic acid is obtained.
Example 50
1-(4-Benzoylthio-2-benzylbutanoyl)-L-Proline
By substituting 4-bromo-2-benzylbutanoic acid for
the 4-,bromo-2~methylbutanoic acid in the procedure of
Example 47, 1~(4-benzoylthio-2-benzylbutanoyl)-L-proline ,
is obtained.
~xample 51 '
1-(4-Mercapto-2-benzylbutanoyl)-L-Proline
:,~
By substituting 1-(4-benzoylthio-2-benzylbutanoyl)-L-
proline for the 1-(4-benzoylthiobutanoyl)~L-proline in the
procedure of Example 45, 1-(4-mercapto-2-benzylbutanoyl)-
L-proline is obtained.
xample 52
1-(4-Mercaptobutanoyl)-L-I~ydroxyproline , ,~
By substituting L-hydroxyproline for the L-prolin~e
in the procedure of Example 44 and subjecting the product to ,;
ammonolysis as in Example 45, 1-(4-benzoylthiobutanoyl)-L-hydroxy~
proline and 1~(4-mercaptobutanoyl)~L-hydroxyprolille, respectlvely,
are obtained.
Example 53
1-(4-~lercaptobutalloyl)-L-~ze~idinc-2-Carboxylic ~cid ',
~y SU~S~itU~illc3 1. a~c~idine-~-carboxylic acid or ~hc
L-proline in tlle proccdurc of l,xam~le ~4 and subjec~ c~ e
:
-38-
~ ~ z~ 37 HA135b
product to ammonolysis as in E~ample 45, 1-(4-bellzoyltllio-
butanoyl)-L-azetidine-2-carboxylic acid and 1-(4-merca~to-
butanoyl)-L-azetidine-2-carboxylic acid, respectively, are
o~tained.
~ xample S4
1- (4-r erca~to~utanoyl)-L-Pipecolic ~cid
By substitutinq L-pipecolic acid for the L-prolinc in
the procedure of Example 44 and subjecting the product to
ammonolysis as in Example 45, 1-(4-benzoylthiobutanoyl)-L-
pipecolic acid and 1-(4-mercaptobutanoyl)-L-pipecolic acid,
respectively, are obtained.
Example 55
1-(3-~cetylthiobutanoyl)-L-Proline tert-butyl Ester
Dicyclohexylcarbodiimide (6.2 g.) and 3 acetylthio-
butyric acid (4.36 g.) are added to a solution of L-proline
- tert-butyl ester ~5.1 g.) in dichloromethane (60 ml.) stirred
in an ice bath. After 15 minutes the ice ~ath is removed
and tlle ~ixture is stlrred at room temperature ~or i6 hours.
The precipitate is filtered, the filtrate is concentrated to
dryness and the residue is chromatocJraphed on a columll of
silica gel with chloroforln to o~tain l-(3-ace~ylthiobu~anoyl)-
L-proline tert-butyl ester, yield 5.2 g.
E~ample 5G -
1-(3-Acetylthio~utanoyl)-L-Proline
_
The 1-(3-acetylthiobutanoyl)-L-proline tert-butyl ester
of Example 55 (5.2 g.) is dissolved in a mixture of tri~luoro-
acetic acid (60 ml.) and anisole (30 ml.) and the solution
is kept at room temperature for one hour. The solvents are removed
in vacuo and tlle residual 1-(3-acetylthiobutanoyl)-L-proline
.
is reprecipitated from e~her-hcxalle several timcs, yield
-39-
HA135b
2~;37
4 g.. The dicyclohexylaminc salt is made by the procedurc
of ~xample 44, m.p. 175-176.
_xample 57
1-(3-Mcrcaptobutanoyl)-L-Prolinc
~ The 1-(3-acetylthiobutanoyl)~L-prolil~e of
Example 56 (0.86 ~.) is dissolved in 5.5 N. methanolic
ammonia (20 ml.) and the reaction mixture is stored at room
temperature for 2 hours. The solvent is removed in vacuo
and the residue chromatographed on an iOII exchange column
(Dowex 50) with water. The fractions containing the desired
1-(3-mercaptobutanoyl)-L-proline are pooled and lyophilized, ~
yield 0.6 g. The dicyclohexylamine salt is produced by the ~ - -
procedure of Example 44, m.p. 183~-184 .
~ : .~ ~,'
1-[3-[[~Ethoxy)carbony1)thio]propanoyl]-L-proline
Ethyl chloroformate (1.2 g.) is added to a solution of
3-mercaptopropanoyl-L-proline [2.03 g.) in normal sodium bicar-
bonate (30 ml.) and the mixture is stirred vigorously at 5
for one hour, and for two hours at room temperature~ After
acidification w1th concentrated hydrochloric acid, the mixture
is extracted with ethyl acetate. The organic phase is
washed with water, dried over magnesium sulfate, an~ concentra-
ted to dryness to yieId 1-[3-[[(ethoxy)carbonyl]thio]propanoyl]-
L-proline.
;'-'
-40-
. J
~1~233~
HA135b
Example 59
1-[3-[[(Ethoxy)thiocarbonyl]tilio]propanoyl]-L-prolille
Aqueous 2~ sodium hydroxide (25 ml) and 3 bromopropionyl
chloxide (8.5 C3) are added to a solution of L-prolinc (5.75 g)
in N sodium hydroxide (50 ml) chilled and stirrcd in an icc
bath. ~fter five minutes the ice bath is removed and the ~;
-: ,
stirring is continued at room temperature. ~ft~r three hours
ethyl xantogenic acid potassium salt (9.6 g) is added and the
mixture is stirred overnight at room temperaturc. The solution
is acidified with concentrated hydrochloric acid and e~tractcd
with ethyl acetate. The organic layer is concentrated to dry-
ness and the residue is chromatographed on a column of silica
gel with a mixture of benzene-acetic acid (7 1) as solvent, ~o
yield 1-[3-[[(ethoxy)thiocarbonyl]thio~;~ropaDoyl]-L-proline,
m.p. 94-95-
xam le 60
1-[3-[[(Benzylthio)carbonyl]thio]propanoyl]-L-proline
A solution of benzylthiocarbonyl chloridc (11 m;) in
dioxane (20 ml) is added in five portions to a solu~ion o~
''' :-
1-(3-mercaptopropanoy1)-L-proline (1.6 g) in normal soclium
bicarbonate (24 ml) chilled in an ice bath, over a period of
30 minutes. The ice bath is removed and the stirriny is
.
continued for 2.5 hours at room tempera~ure. ~,fter acid- -
ification with concentrated hy~rochloric acid, the aqueOu
,
phase is extracted with ethyl acetate. The organic phase
is dried over magnesium sulfate and concentra~ed to dryness
to yield 1-[3-[[(benzyl~hio)carbonyl]thio]propanoyl]-L-proline.
..~
-41- .
,' :
: ,: ,
3~
HA135b
~xample 61
-[3~[[(~thylthio)thiocarbonyl]thio]propanoyl]-L-proline
~ queous 2N sodium hydroxide (25 ml) and 3-bromopropion~fl
chloride (S.~ g) are added to a solution of L-L~rolinc (5.75
in N sodium hydro.Yide (50 ml) chilled and stirrcd in ~n icc
bath. After ~ive minutes, the ice bath is removed and the
stirring is continued at room temperature. i~fter t}lr~e hours,
ethyl trithiocarbonate potassium salt (10.5 g) is added and
the mixture is stirred at room temperature overnight. Artcr
acidification with concentrated hydrochloric acid, the mixture
is extracted with ethyl acetate. The oryanic layer is dricd
over magnesium sulfate and concentrated to dryncss to yield
1-[3-[[(ethylt]lio~liocarbonyl]tll o]~rcpanoyl,-L-~~oline.
Example 62
3-[[_(Methylamino)thiocarbonyl]thio]propionic acid
Methylisothiocyanate (4 g) is added to a solution of
- -, :
3-mercaptopropionic acid (5.3 g) in a mixture of pyridinc
(250 ml~ and 0.5 N sodium hydroxide (100 ml). Thc solu~ion
is kept at 40 ~or t~o hours and concentrated to dryncss
ln vacuo. The residue is dissolved in water (100 ml.),
acidified with concentrated hydrochloric acid and cxtracted
with ether. The organic phase is concentrated to dryness
to yield 3-[[(methylamino)thiocarbonyl]thio]propionic acld,
m.p. 86-87.
,
,, ' ~ ,
-42- ;
" , " ' ':
337
HA135b
Example 63
1-[3~[[(Methylamino)thiocarbonyl]thio]propanoyl~ L-proline
tert-butyl ester
.
To a solution of L-proline Lert-butyl estcr (1.71 g) and
hydroxybenzotriazole (1.35 g) in dichlorosnethanc (10 ml) chilled
and stirred in an ice bath, dicyclohexylcarbodiimide (2.OG g)
and 3-methylaminothiocarbonylthiopropionic acid (1.79 g) are
added~ ~fter 15 minutes, the bath is removed and the stirring
is continued overnight. The precipit~te is filtercd off and
the filtrate is diluted with ethyl acetate and ~ashed neutral.
~he organic pllasc is conccntrated to dryncss to yicld
1-[3-~[(methylamino)thiocarbonyl]thio]propanoyl]-L-proline
tert-butyl ester, m.p. 129-130 .
Example 64 ~;
1-[3-[[(Methylamino)thiocarbonyl]thio]propanoyl]-L-proline
A) 1 (Methylaminothiocarbonylthiopropanoyl)-L-prol1ne tcrt-
butyl ester (0.98 g) is dissolved in a mixture of anisole (3.6
ml) and trifluoroacetic acid (7.5 ml). ~fter one hour at room
~emperature the mixture is concentrated to dryness ln vacuo and ~ -~
the residue precipitatcd from ether-hexane tllrcc ~imcs. This
material is c~romatographed on a column of silica gel wlth a
solvent mixture of benzene-acetic acid (75:25) to yield 1-[3_ ~;
[[(methylamino)thiocarbonyl]thio]propanoyl]-L-proline,
Rf = 0.4 [silica gel-benzene:acetic acid (75:25)]. The -
dicyclohexylammonium salt has m.p. 127-129 ;
-43- -
~Z~37
HA135b
B) ~lethylisot~iocyanate (4 g) is added to a solution of 3~
mercaptopropanoyl-L-proline (10.1 g) in a rnixture of pyridine
(250 ml) and 0.5 N sodium hydroxide (100 ml). The solution is
~ept at 40 for two hours and concentrated to dryness in vacuo.
The residue is dissolved in water (100 ml), acidified ~ith con- ,~
centrated hydrochloric acid ana extracted with ethyl acetate~
The organic phase is concentrated to dryness to yield
1-[3-[[(methylamino)t!:'oca-bonyl]thio]propanoyl]-L-proline.
Example 65
.
1-[3~[[(Ethylamino)carbonyl]thio]propanoyl]-L-proline '
Ethyllsocyanate (0.45 ml) is added to a solution of
1-(3-mercaptopropanoyl)-L-proline (1 y) in a mix~ure of N
sodium hydroxide (S ml) and pyridine (5 ml). The solution
is heated at 40 for four hours and concentral:ecl _l~ vacuo.
The residue is distributed b tween 0.1 ~ hydrochloric acid
and ethyl acetate. The organic layer is washed wi~h water,
dried over magneslum sulfate and concentrated to dryness to
yield 1~[3-[[(ethylamino-)carbonyl]thio]proi?anoyl~-L-~~olin~
The dlcyclohexyIamrnonium salt i's prepared by adding dicyclo
hexylamine to a solution of the free acid in ethyl acetate,
m.p. 150-152 .
1-[3-[[(Ethoxy)carbollyl]~llio]-2-rnethylprc)l)alloyl]-L-I~loline ~ ,
By substituting 1-(3-mercapto-2-methylpropalloyl)-L-prolllle
for the 3-mercap~opropanoyl-L-proline in the procedure of
Exar,nple 58,1-[3-[[(ethoxy)carbonyl3thio]-2-me~hyll?ropanoyl]-L-
proline is obtained.
` '~
, ' '
,: . , , ' ' " ~, ' ' '
337t
HA135b ,
. Example h7 , ~ ~
:. -
1-[3-~[(thoxy)carboTlyl]tllio~butanoyl]--I.~urolille ~ '
~ , .
By substituting 1-[3-mercaptobu~anoyl)-L-proline for the .
3~mercaptopropanoyl-L-proline in the procedure of ~xample 58, 1-
[3-[[(ethoxy)carbonyl]thio]butanoyl]-L-proline is obtained.
Exarnplc 68
1-[3-[[(Ethoxy?thiocarbonyl]thio]propanoyl]-L-azetidine-2- ~;
carboxylic acid
By substituting L-azetidine-2-carboxylic acid for ; ,~
L-proline in the procedure of Example 59, 1-[3~[~(ethoxy)~
thiocarbonyl]thio]propanoyl]-L-azetidine-2-carboxylic acid -~
is obtained. ~',
Example 69
1-[3-[[(~thoxy)thiocarbonyl]thi-o~]propanoyl]-L-pipecolic acid
; By substituting L-pipecolic acid for L-proline in the '',
procedure of Example 59, l-[3-~l(ethoxy)thiocarbonyl]thio)pro-
panoyl]-L-pipecolic acid is obtained.
' Example 70 ~'
20 1-[4-[[(Benzyltllio)car_ollyl]tllio]butanoylJ~L-~ro~ o - '~
.
By substituting 4-mercaptobutanoyl-L-pro1ine for ~he 3~
mercaptopropalloyl-L-prolille in the procedure of Exam!?lc 60, 1-
[4-[~(benzylthio]carbonyllthio]butanoyl]-L-proline is obtained. ,~
' xample~71~
1-[2-[[(Benz~ltllio)carbonyl]thio]propanoyl]-L-!~rolinc
~y substituting 2-mercaptopropanoyl-L-prolirle Eor the 3-
mercaptopropanoyl-L-proline in tlle procedure of ~xam~)le 60, 1-
[2-[[(bcn~yltllio)car~onyl~thio]propanoyl]-L-prolille is obtained.
-45-
HA135
Example 72
1-[3-[[(Etl~yltllio)thiocarbollyl]thio~ o~anoyl]~l,~~rolillc metllyl ester
-- -- . ,
A solution of 1-[3-[[(ethylthio)thiocarbonyl]thio]propanoyl]~
L-proline in ethyl acetate is treated with an ethereal so].ution ''
'' of diazomethane until persistent yello~ color. ~ cr discharging ''
the yellow color with a few drops of acetic acid, tlle solvents
are removed in vacuo to yield 1-[3-[[(ethylthio)thioca,rbonyl]thio]~
propanoyl]-L-proline methyl ester.
~xampl~ 73 '
1-[3-[[(methylamino)thiocarbonyl]thio]propanoyl]-5=h~dro~y-L-
pipecolic acid
. .
By substituting 1-[3-mercaptopropanoyl)-5-hydroxy-L-pipecolic
acid for the 3-mercaptopropanoyl-L-uroline in the Procedure B
of Example 64,1-[3-[[(methylamino~thiocarbonyl]thio]~propanoyl]- - ~ ;
5-hydroxy-L-pipecolic acid is obtained.
~xample 74
1-[3-[[(Methylamino)thiocarbonyl]thio]--2-methylpropal;oyl]-L- -
proline amide ` '~
By substituting 1-(3-mercapto-2-methylE~rol~anoyl)-L-proline
amide for the 3-mercaptopropanoyl-L-proline in tlle Proce~ure B
of Example 64,1-[3-[[(methylamino)thiocarbotlyl]tllio]-2-methyl-
propanoyl]-L-proline amide is obtained. ~ ~ ,
Example 75 ' ''
1-[3-[[(Phcnoxy)carbonyl]tllio]propanoyl]-L-E)roline
By substitutin~ phenylchloroformate ~or ethyl chloro~orrnate
in ~I~o l~r~c~lure ~L ~Y~ lc 5~,]-~3-[~ Y)~ar~ y~ i
~ro~a~oyl]-L-~rolille is o~tailled.
' -46-
~ 23~7 HA135b
. ~xamp,le 76
.
1-[3--[[(Phenoxy)carbonyl]thio]butanoyl]-L-proline
:
By substituting phenylchloroformate for the ethyl
chloroformate and 4-mercaptobutanoyl-L-proline for, the
3-mercaptopropanoyl-L-proline in the procedure o~ Example 58,
1-[3-[[(phenoxy)carbonyl]thio]butanoyl]-L-proline is obtained. '
Example 77
1-[3-[[(Phenylamino?carbonylltllio~propatloylJ-L-Lirolillc -'
By substituting phenylisocyanate for the ethylisocyanate
in the procedure o~ ~xample 65,1-[3-[[(phenylamino)carbonyl]-
thio]propanoyl]-L-proline is obtained. ~ - , ,
- Example 78
1-[3-[~(Phenetllylamino)carbonyl]~hiojL~ro~arloyl]-l.-l~ro]il)e
By substituting phenethylisocyanate ~or thc c~hylisocyanate
in the procedure o~ Example 65,1-[3-[[(phene~hylalnino)carbonyl]- `~
thio]propanoyl]~L-proline is obtained. '
,~ample 7
1-[3-[[(Ethylamino)carbonyl]thio]-2-benzylpropanoyl]-].-proline
By substituting 1-(3-mercapto-2-benzylpropanoyl)-L- ;
proline for the 1-(3-mercaptopropanoyl)-L-proline in the'
procedure of Example 65, 1-[3-[[(ethylamino)carbonyl]thio]-
2-benzylpropanoyl]-L proline is obtained. , `~
-47-
37
Example_80
1-(3-Methylthiopropanoyl)-L-proline
,~ .: ' . '
A) Methyl 3-methylthiopropionate (51 g) is saponified with -
a ]0% sodium hydroxide solution (150 ml, 30 minutes at 100).
The cooled solution is extract~d with ether and then acidified.
The crude acid thus obtained is distilled and converted to
the acid chlorid~ with thionyl chloride.
A solution of L-proline (11.5 g) in N sodium hydroxide ~100 cc)
i5 chilled in an ice bath and the 3-methylthiopropanoic acid
chloride (6.9 g) is added dropwise with vigorous stirring over
a ten minutes period. After ~ive hours the reaction mixture
is acidified and extracted with ethyl ether to yield 1-(3-
methylthiopropanoyl)-L-proline. The dicyclohexylammonium salt
is prepared by adding dicyclohexylamine to a solution o~ the
free acid in ethyl acetate, m.p. 169-171.
~ ~.
.~
~) Methyl iodide ~71 g) is added to a solution of 1-(3- ;~
mercaptopropanoyl)-L-proline ethyl ester tll5 g) and sodium
(11.5 g) in ethanol (400 ml). The reaction is allowed to
proceed overnight, the ethanol is removed in vacuo and the
residue is dissolved in a mixture of ethyl acetate and water. ~
The organic layer is dried and concentrated to dryness in vacuo. ~ ;
,~ , .
The resulting 1-(3-methylthiopropanoyl)-L-proline ethyl ester
(98 g) is suspended in a mixture of methanol (200 ml) and 5 N
sodium hydroxide (200 ml) and stirred at room temperature for
five hours. The methanol is removed in vacuo, and the aqueous
phase is extracted with ethyl acetate, acidified and reextracted
with ethyl acetate. This last organic phase is washed with
water, dried and concentrated to dryness to yield l-(3-methylthio-
propanoyl)-L-proline.
~ 8-
~2~37
Example 81
Aqueous 2 N sodium hydroxide (25 ml) and 3-bromopropionyl
chloride (8.5 g) are added to a solution of L-proline (5.75 g)
in N-sodium hydroxide (50 ml) chilled and stirred in an ice
bath. After five minutes, the ice bath i5 removed and the
stirring is continued for three hours at room temperature. The
reaction mixture is acidified with concentrated hydrochloric acid
~nd extracted with ethyl acetate. The organic la~er is washed
with water, dried and concentrated to dryness in vacuo. The
residue is dissolved in a mixture of 4-chlorobenzenethiol (8 g),
sodium hydroxide (4~2 g) and ethanol (300 ml). The solution is
refluxed for 6 hours. The solvent is removed in vacuo and the
residue is dissolved in water, acidified with concentrated hydro~
chloric acid and extracted with ethyl acetate. The organic layer
is washed with water, dried, and concentrated to dryness in
vacuo to yield 1-~3-(4-chlorophenylthio)propanoyl]-L-proline.
Example 82
1,[[(3-Benz~ylthiomethyl)thio]propanoyl]-L-pro.line - ,.
1-(3-Mercaptopropanoyl)-L-proline (8.1 g) lS dissolved
in boiling liquid ammonia (100 ml) and small pieces of sodium
are added until permanent blue color is obtained which is then
discharged with a small piece of ammonium chloride. Benzyl-
thiomethyl chloride (6.9 g) is added and the ammonia is allowed
to evaporate. The final traces of ammonia are removed in
vàcuo, the residue is dissolved in water and extracted with
ethyl acetate. The aqueous phase is acidified with concentrated
hydrochloric acid and extracted with ethyl acetate. The organic
layer is washed with water, dried and concentrated to dryness
~ -49-
37
HA135b
to yield 1-[[(3-benzylthiomethyl)thio]propanoyl]-L-proline.
Lxample 83
1-[[(3-Acetamidomethyl)thio]propanoyl]-I,-proline
.
1-(3-Mercaptopropanoyl)-L-proline (2 g~ and N-h~rox~y-
methylacetamidc (0.89 ~) are dissolved in tri~luoroacetic acid
(10 ml) and the solution is storcd at room tem~eraturc for onc
hour. The excess ~rifluoroacetic acid is removcd ln vacuo and
the residue is precipitated several timcs from ether-hexane.
Finally, the residue is distributed between dilute h~drochloric
acid and ethyl acetate. The organic layer is washcd with water,
dried and concentrated to dryness to yield 1-[[(3-acetamido-
methyl)thio]propanoyl]-L-proline.
Example 8
l-(Methylthioacetyl)-L-proline
By substituting me~hyl methylthioacetate for the methyl
3-methylthiopropionate in the Procedure ~ o~ ample 80, 1
(methylthioacetyl)-L-proline, m.p. 1~3-124, is obtained.
Example 85
1-~Benzylthioacetyl)-L-prolille
- , .
3y substituting benzylthioacetyl chloride for ~he 3-metl~
thiopropanoyl chloride in the Procedure ~ o~ ~xalllple 80, 1- ~ ~p
(benzylthioacetyl)-L-proline, m.p. 86-88, is obtained.
'~
-50-
HA135b
Example 86
1-[3-[(2-Phenyletllyl)tl~io)propalloyl]-I.-pLolirle
By substitutincJ phenethylbromide ~or thc methyi iodidc in-
the Pxocedure B oE ~xample 80, 1-~3-l(2-plle~lylcthyl)thio]propanoyl]-
L-pxoline is obtained.
i~xamPle 8
- [3- [ (Triphenylmeth ~ hio~propanoy1]-L-prc)linc
Y ~:
10By substituting triphenylmethyl chloride for tllc metllyl
iodide in the Procedure B of Lxample 80, 1-[3-~(triphenyll11ethyl)-
thio]pxopanoyl]-L-proline is obtained.
Example 88
1-(3-~lethylthio-2-metllylpropanoyl)-L-proline amidc
- - ;'
By substituting 1-(3-mercapto-2-methylpropanoyl)-L-uroline
amide for the 1~(3-mercaptopropanoyl)-L-proline ethyi estcr in
the Procedure B of Example 80 and eliminating the saponiication
step, 1-(3-methylthio-2-methylpropanoyl)-L-Proline amide lS
obtained.
Lxample 89
1-(3-~;ethylthiopropalloyl)-I,-azetidille-2-carl)oxylic acid-
By substituting L-azetidine-2-carboxylic acid for the L- ;
proline in tle Procedure A of Lxample 80,1-(3-~,ethylthioprpPanoyl)
L-azetidine-2-carboxylic acid is obtained.
~ z
~37 HA135b
~xample 90
1-[3-(4-~cthoxypllellylthio)pLol)anoyl]-L,-~rolinc
By substitutiny 4-metlloxybenzenet}liol ~or the 4-chloro-
benzenethiol in the procedure of ~xample 81, 1-[3-~1-methoxy-
phenylthio)propanoyl]-L-proline is obtairled. ~ ;
~,x.lrl~lc 91
1-(3-Methylthiopropanoyl)-L-pipecolic acid
By substituting L-pipecolic acid ~or ~hc L,-prolille in ~he
Procedure A of Example 30,1-(3-methylthiopropanoyl)-L~pipecolic
acid is obtained. - ~-
Example 92
1-[2-(~-ChloL-oL~Ilenyltllio)propanoyl]-L-pro]ille ;~
By su~stituting 2-bromopropionyl chloride for the 3-
bromopropionyl chloride in the proced~lre of ~xanlple a
~2-(4-chloropllenyLtllio)propanoyl]-L-proline is ob~aiAcd.
F'xamplc 93
.
1-~3-[(DiL~hellylll~ctllyl)thio]-2-bcll~ylL~ropallovl)]-l,-l~Lolinc
" ~ "
Diphenylmethanol ~0.92 y) and 1-(3-mercapto-2-bell~ylpropanoyl)-
L-proline (1.5 y) are dissolved in trifluoroacetic acid (10 ml)
and the solution is kept at room temperature for 30 minutes. The
excess tri1uoroacetic acid is removed in vacuo to yield 1-[3-
~(diphenylmethyl)thio]-2-benzylpropanoyl]-L-prolille.
-52-
1~(}233
:
Example 94
1-[4-(4-Chlorophenylthio)butanoyl]-L-proline
By substituting ~-bromopropionyl chloride for the 3-
bromopropionyl chloride in the procedure of Example 81, 1-[4-(4-
chlorophenylthio)butanoyl]-L-proline is obtained.
Example 95
1-~3-[(Benzyltlliomethyl)thio]butanoyl~-L-prolihe
By substituting 3-mercaptobutanoyl-L-proline for the
3-mercaptopropanoyl-L-proline in the procedure of Example 82,
1-[3-~(benzylthiomethyl)thio]butanoyl]-L-proline is obtained.
Example 96 '~~
1-[~4-[(Acetamidomethyl)thio]-2-methylbutanoyl]-L-proline
By substituting 1-(4-mercapto-2-methylbutanoyl)-
L-proline for the 1-(3-mercaptopropanoyl)-L-proline in the
procedure of Example 83, 1-[~[4-(acetamidomethyl)thio]-2-
methylbutanoyl]~L-proline i9 obtained.
Example 97
1-[3-(Ethyldithio)propanoyl]-L-proline
A) 3-Mercaptopropanoyl-L-proline (10 g) is added to a
solution of ethylthiosulfinate (8.4 g) in methanol (100 ml)
and the reaction mixture is stirred vigorously at room '~
temperature for four hours. The methanol is removed In
vacuo to yield l-(3-ethyldithiopropanoyl)-L-proline.
B) A solution of ethylthiosulfinate (8~4 g) in
ethanol (50 ml) is added to an aqueous solution of 3-mercapto-
propanoyl-L-proline (10 g) maintained at pH 6-7 by careful
addition of sodium hydroxide. The mixture is stirred vigorously
-53-
~Z33~
at room temperature until negative thiol reaction. The mix-
ture is diluted with water, adjusted to p~ 8 and extracted
with ethyl acetate, the aqueous phase is acidified to pH 3
and extracted again with ethyl acetate. This latter extract
is washed with water, dried and concentrated to dryness to
yield 1-[3-(ethyldithio)propanoyl]-L-proline.
Example 98
1-[3-[t4-Methylphenyl)di'thio]propanoyl]-L-proline '~
,~'.''
A solution of 4-methylphenylsulfenyl chloride (1.76 g.)
in ether (20 ml) is added to a solution of 3-mercaptopropanoyl- ' ~;
L-proline (2 g) in 0.5 N sodium hydroxide (20 ml~ chilled in
an ice bath. The mixture is stirred vigorously for one hour,
and the aqueous phase is separated, acidified wlth concentrated
hydrochloric acid and extracted with ethyl acetate. The or~anic
phase is washed with water, drled and concentrated to dryness
to yield l-[[3-(4-me~hylphenyl)dithio]propanoylJ-L-proline. -
Example''99
'1-[3-~Phenyldi_hio-propanoyl]-L-proline
By substituting phenylthiosulfinate [prepared ~rom phenyl-
disulfide according to U. Weber and P. Hartter, Z. Physiol. Chem.,
351; 1384 (1970)] for the ethylthiosulfinate in the procedure of
Example 97, l-[3-(phenyldithio-propanoyl]-1-proline is obtained. '
Example'l'00
1-[3-[(2-Phenylethyl)dithio]propanoyl]-L-proline
' :' .
By substituting 2-phenylethylthiosulfinate (prepared from
phenethyldisulfide) for the ethylthiosuflinate in the procedure
of Example 97, 1-[3-[(2-phenylethyl)dithio]propanoyl]-L-proline
is obtained.
-54-
~ ~ r? ~ ~ ~:~w
Example 101
prop~ ~nyl] L-proline
To a solutlon of ~ _E(~u~inylthio)-bis-l3~prOpanoyl)]-
biS-L-proline (21 g) in methanOl ~lO0 ml), mercaptoethanol(4~2 g)
is added and the reaction mixturc I~ stirred vigorously at room
temperature for four h~ur5. The m~thanol is removed ln vacuo
and t~le residue is pruified b~ chro~atography on a silica gel
column to yield 1-[3-[(2-hydroxye~hyl)dithio]propanoyl]-L-proli~e.
'Exampl'e 102
. _ .
'l-[?-(Ethyldithio)propanoyl]-L-pro ~
By substituting 2-mercaptopropanYl-L-Proline for 3-
mercaptoprOpanoy~ proline in the procedure of Example 97,
1-[2-(ethyldithio~propanoyl]-L-proline is obtained.
'Example'103
1-'[3-[(4-Met-hylphenyl)dithio]butanoyl]--L-proline
By substituting 3-mercap~obutanoyl-L-pxoline for the 3- -''
mercaptopropanoyl-L-proline in the procedure of Example 98,
1 [3-~4-methylphenyl)dithio]butanoyl]-L-proline is obtained.
'Example l_
1-[3-(Ethyldi-thio)-2-methylpropanoyl]-L-proline methyl ester
By substituting 1-(3-mercaptO-2-methylpropanoyl)-L-proline
for the 3-mercaptopropanoyl-L-proline in the procedure of Example
97 and then treating the product with ethereal diazomethane as
in the procedure of Example 72, 1-[3-(ethyldithio3-2-methylpro-
panoyl]-L-proline methyl ester i5 obtained.
-55-
, ~
~2~37 :: -
Example 105
1-[3 (Ethyldithio)propanoyl]-L-azetidine-2-carboxylic acid
By substituting 3-mercaptopropanoyl-L-azetidine-2-
carboxylic acid for the 3-mercaptopropanoyl-L-proline in the
procedure of Example 97, 1-[3-(ethyldithio)propanoyl]-L-aze- ~'
tidine-2-carboxylic acid is obtained.
Example 106 ~
1-[3-[(4-Methylphenyl)dithio]-2-methylpropanoyl]-L-hydroxyproline , ~ ~'
By substituting 1-(3-mercapto-2-methylpropanoyl)-L-
hydroxy proline for the 3-mercaptopropanoyl-L-proline in the
procedure of Example 98, 1-[(3-[4-methylphenyl)dithio]-2
methylpropanoyl]-L-hydroxyproline is obtained.
Exampl'e'1'07
1-[4-~Ethyldithio)butanoyl]-L-pipecolic acid
- ::
By substituting 4-mercaptobutanoyl-L~pipecolic acid for
the 3-mercaptopropanoyl-L-proline in the procedure of Example 97,
1-[4-(ethyldithio-butanoyl]-L-pipecolic acid is obtained.
Example_1`08
1-[3-(Ethyldithio)propanoyl]-5-hydroxy-L-pipecolic acid
By substituting 1-(3-mercaptopropanoyl)-5-hydroxy-L- ,
pipecolic acid for the 3-mercaptopropanoyl-L-proline in the
procedure of Example 97, 1-[3-(ethyldithio)propanoyl]-5-hydroxy-
L-pipecolic acid is obtained.
-56-
Z~t37
Example 109
1-[3-~(2-Amino-2-carboxyethyl)dithio]propanoyl]-L-proline
A 0.5 M solution of thiocyanogen in glacial ac~tic acid
is prepared by shaking for ten minutes in a sealed flask 600 my
of dry lead thiocyanate with a solution of 75 ~1 of bromine in
3 ml of acetic acid. After removal of lead bromide and excess
lead thiocyanate by centrifugation, 2.5 ml of this solution is
mixed with 2.5 ml of a 0.41 M solution of cysteine hydrochloride
previously neutralized with dilute sodium hydroxide. This
mixture is immediately added to 0.75 ml of a 1.9 M solution of
3-mercaptopropanoyl-L-proline previously neutralized with dilute
sodium hydroxide. After twenty minutes the mixture is titrated
to incipient browm color with alcoholic iodine, and adjusted to
pH 3. The precipitate is removed by filtration and the filtrate
is applied to a column of cation exchange resin (Dowex 50). The ~ ,
co],umn is washed with water until no more acidic material is
removed and then eluted with pyridine-acetate buffer pH~6Ø
The fractions containing the disulfide of cysteine and 3-
mercàptopropanoyl L-proline are pooled and concentrated to
dryness.
Example l'10
[Dithiobis)4-propanoyl)]-bis-L-proline
3-Mercaptopropanoyl-L-proline (0.95 g) is dissolved in
water (20 ml) and the pH is adjusted to 6.5 with N-sodiurn
hydroxide. An ethanolic solution of iodine is added drop-
wise while rnaintaininy the pH at 6.5 with careful addition
of N sodium hydroxide. When a perrnanent yellow color is
obtained the addition of iodine is stopped and the color
-57-
37
HA135b
is discharged with a small anlount of sodiuln thiosula~e.
The reaction mixture is acidi~ied with concentratcd hydro-
chloric acid and e~tracted with ethyl acetate. The orcJanic
phase is washed with water, dried and concentrated ~o dryness
to yield l,l'-[dithiobis(3-propanoyl)]-bis-I,-proline. The di-
cyclohexylammonium salt is prepared by addition of dicyclo-
hexylamine to a solution of the free acid in acetonitrile,
m.p. 179-180.
xample 111
1,l'-[Dithiobis(2-D-lllethyl-3-p-ropanoyl)l-bis~L-proline
By substituting 3-mercapto-2-D-methylpropanoyl-L-
proline for the 3-mercaptopropanoyl-L-proline in the procedure
of Example 110, 1,1'-[dithiobis(2-D-methyl-3-propanoyI)]-bis~
L-proline is obtained, m.p. 236-237 .
Example 112
l~l'-[Ditlliobis(2-propanoyl)-bis-L-proline
By substituting 2-mercaptopropanoyl-L-prolin~ for the
3-mercaptopropanoyl-L-proline in the procedure of Example 110,
1,1'-[dithiobis(2-propanoyl)]-bis-L-proline is obtained.
- Exampl_ _13
l,l'-(Dithiobisacetyl)-bis-L-hydroxy proline
By substituting l-(2-mercaptoacetyl)-L-hydroxyproline -
for the 3-mercaptopropionyl-L-proline in the procedure of
Example 110, l~ (dithiobisacetyl)-bis-L-hydroxyproline is
obtained.
Example 114
l,l'-(Dithiobisacetyl)-bis-L-azc~idine= 2-car~ox~lic_aci
By substitutiny 1-(2-mcrcaptoacetyl)-L-aze~ e-2- i
carboxylic acid ~or the 3-mercaptopropanoyl-L-proline in the
procedure of ~xample 110, 1,1'-(dithiobisacetyl)-bis-L- ~ -
azetidine-2-carboxylic acid is obtained.
~,
-58-
, .: . . " , :
.. . ..
~2~7
HAl35b
Example ll5
-
l,l'-[Dithiobis(3-propanoyl)]-bis-L-pipecolic acid
By substituting 3-mercaptopropanoyl-L-pipecolic acid
for the 3-mercaptopropanoyl-L-proline in the procedure of
Example llO, l,l'-[dithiobis(3-propanoyl)]-bis-L-pipecolic
acid is obtained.
Example ll6
l,l'-[Dithiobis(3-propanoyl)]-bls-~ etllyl-L prolillc
By substituting l-(3-mercaptopropanoyl)-4-mcthyl-L-proline
for the 3-mercaptopropanoyl-L-proline in the procedure of ~xanlple
llO,l,l'-[dithiobis(3-propanoyl)]-bis-4-n)et}-yl-L-proline is
obtained.
Example 1l7
l,l'-[Dithiobis(3-propanoyl)]-bis-S-I~ydro,Yy~ )iL~ecolic acid
By substitutin~ 3-mercaptopropanoyl)-S-hydroxy-L-pipecolic
acid for tlle 3-1nercaptopropanoyl-L-prolille in tllc procedurc of
Example llO,l,l'-[dithiobis(3-propanoyl)]-bis-5-hydroxy-L-pipecollc
acid is obtained.
Example ll8
l,l'-[dithiobis(2-benzyl-3-propalloyl)J-bis-L-pl-olille
By substituting l-(3-Mercapto-2-benzylpropanoyl)-L-proline ~ ;
for the 3-mercaptopropanoyl-Lrproline in the procedure of ~x~nple llO, l,l'-
~[dithiobis(2-benzyl-3-propanoyl)]-bis-1-prolille is obtained.
_59_
2337
HA135b
Example 119
1,1'-LDithiobis(2-mc~hyl-3-propalloyl)]-bis-L-~ coli( aci~
.
By substitutincJ 1-(3-mercapto-2-metllylpropanoyl)-L-pipccolic
acid for the 3-mercaptopropanoyl-L-prolinc ill thc procedure of
Example llO,l,l'-~dithiobis(2-methyl-3-~ropanoyl)]-bis-L-pipecolic
acid is obtained.
Exarnple 120
1,1'-lDithiobis(4-butanoyl)]-bis-L-prolinc
. :
,,
By substituting 4-mercaptobutanoyl-L-prolinc for the
3-mercaptopropanoyl-L-proline in the procedure of ~:ample
110, 1,1'-[dithiobis(4-butanoyl)]-bis-L-proline ~is obt~ined.
2Yample 121
1,1'-[Ditlliobis(2-benzyl-4-butanoylj]-b~s-L,-proline
By substituting 1-(4-mercapto-2-ben yl~u~anoyl)-L-proline
for the 3-mercaptopropanoyl-L-proline in the procedure of
Example llO,l,l'-[dithiobis(2-benzyl-4-butalloyl)]-bis-L-prollne
is obtained.
~xarnple 122
. :.
1,1'-~Dithiobis(3-butanoyl)]-bis-L-prolillc
By substituting 3-mercaptobutanoy1-L-proline for the
3-mercaptopropanoyl-L-prOline in the procedure of ~xample
llo~ -[ditlliobis(3-butanoyl)l-bis-L-proLille is obtained.
,
-60- . ~ -
,. . ' ' : ,
Z~37
Example 123
1,1'-[Dithiobis(3-propanoyl)]-bis-L-proline methyl ester
A solution of 1,1'-[dithiobis(3-propanoyl)]-bis-L-
proline in methanol is treated with ethereal diazomethane
until persistent yellow color. After fifteen minutes a
few drops of acetic acid are added and the solvents are
removed in vacuo to yield, l,l'-[dithiobis(3-propanoyl)]-
bis-L-proline methyl ester.
Example 124
1,1'-[Dithiobis(3-propanoyl)]-bis-L-proline amide
A solution of 1,1'-[dithiobis(3-propanoyl)]-bis-
L-proline methyl ester in methanol is saturated with am-
monia while cooling in an ice-water bath. The reaction
mixture is stored for 16~hours at room temperature in a
pressure bottle, and then the solvents are removed in
vacuo to yield l,l'-[dithiobis(3-propanoyl)]-bis-L-proline
amide.
Example 125
1,1'-[Dithiobis(2-phenyl-3-propanoyl)]-bis-L-proline
By substituting 1-13-mercapto-2~phenylpropanoyl)-
L-proline for the 3-mercaptopropanoyl-L-proline in the
procedure of Example 110, 1,1'-[dithiobis(2-phenyl-3-pro-
panoyl)]-bis-L-proline is obtained.
-61-
! ~j
337
Example 126
[(Sulfinylthio)-bis-(3-propanoyl)]-bis-L-proline_
While cooling in an ice bath 0.12 mole of peracetic
acid is added to a stirred solution of l,l'-[dithiobis(3-
propanoyl)]~bis-L-proline (40 g) in glacial acetic acid
(500 ml). The reaction mixture is allowed to stand over-
night at room temperature and the solvent is then removed
ln vacuo to yield l,l'-[(sulfinylthio)-bis-(3-propanoyl)]-
bis-l,-proline.
Example 127
l,l'-[(Sulfonylthio)-bis-(3-propanoyl)]-bis-L-proline
A 30% solution of hydrogen peroxide (2.0 ml) is
added to a solution of l,l'-[dithiobis(3-propanoyl~]-bis-
L-proline (4 g) in glacial acetic acid ~80 ml) and the
solution is stored for thirty hours at room temperature.
The solvent is removed in vacuo to yield l,l'-[(sulfonyl-
--
thio)-bis-(3-propanoyl)~-bis-L-proline.
Example 128
l,l'-[(Sulfinylthio)-bis-(2-propanoyl)]-bis-L-proline
. ' ' - .
By substituting 1,1'-[dithiobis(2-propanoyl)]-
bis-L-proline for the l,l'-[dithiobis(3-propanoyl)]-bis- -
L-proline in the procedure of Example 126, 1,1'-[(sul- -
finylthio)-bis-(2-propanoyl)]-bis L-proline is obtained.
-62-
~2;~37
Example 129
1 -[(Sulfinylthio)-bis-acetyl]-bis-L-azetidine-2-carboxy-
lic acid
By substituting l,l'-(dithiobisacetyl)-bis-L-azeti-
dine carboxylic acid for the l,l'-[dithiobis(3-propanoyl)]-
bis-L-proline in the procedure of Example 126, l,l'-[(sul-
Einylthio)-bis-acetyl]-bis-L-azetidine-2-carboxylic acid
is obtained.
Example 130
1,1'-[(Sulfinylthio)-bis-(3-propanoyl)]-bis-4-methyl~L-
proline
By substituting 1,1'-[dithiobis(3-propanoyl)]-bis-
4-methyl-L-proline for the 1,1'-[dithiobis(3-propanoyl)]-
bis-L-proline in the procedure of Example 126, l,l'-~(sul-
finylthio)-bis (3-propanoyl)]-bis-4-methyl-L-proline is
obtained.
~ Example 131
1,1'-[(Sulfinylthio)-bis-(2-benzyl-3-propanoyl)]-bis-L-
proline
By substituting 1,1'-[dithiobis(2-benzyl-3-propa-
noyl)]-bis-L-proline for the 1,1'-[dithiobis(3-propanoyl)]-
bis-L-proline in the procedure of Example 126, l,l'-[(sul-
finylthio)-bis (2-benzyl-3-propanoyl)]-bis-L-proline is
obtained.
Ex mple 132
1,1'-[(Sulfinylthio)-bis-(4-butanoyl)]-bis-L-proline
By substituting l,l'-[dithiobis(~-butanoyl)]-bis-
L-proline for the 1,1'-[dithiobis(3-propanoyl)]-bis-L-
proline in the procedure of Example 126, l,l'-[(sulfinyl-
thio)-bis-(4-butanoyl)]-bis-L-proline is obtained.
~ -63-
Z~3~7
Example 133
1,1'-[(Sulfinylthio)-his-(3-butanoyl)]-bis-L-proline
By substituting 1,1'-[dithiobis(3-butanoyl)]-bis L-
proline for the l,l'-[dithiobis(3-propanoyl)]-bis-L-proline
in the procedure of Example 126, l,l'-[(sulfinylthio)-bis-
(3-butanoyl)]-bis-L-proline is obtained.
Example 134
1,1'-[(Sulfinylthio)-bis-(2-methyl-3-propanoyl)-bis-L-pro-
line
By substituting 1,1'-[dithiobis(2-methyl-3-propan-
oyl)]~bis-L-proline for the 1,1'-[dithiobis(3-propanoyl)]-
bis-L-proline in the procedure of Example 126, l,l'-[(sul- -
finylthio)~bis-(2-methyl-3-propanoyl)]-bis-L-proline~is
obtained.
Example 135
1,1'-[(Sulfinylthio)-bis-(2-phenyl-3-propanoyl)]-bis-L-
proline i~
. ..
- :~
By substituting 1,1'-[dithiobis(2-phenyl-3-propa-
noyl)]-bis-L-proline for the 1,1'-[dithiobis(3-propanoyl)]-
bis-L-proline in the procedure of Example 126, l~ (sul-
finylthio)-bis-(2-phenyl-3-propanoyl)]-bis-L-proline is ~
obtained. ~ -
Example 136 ~
1-~3-[[3-(2-Carboxy-l-pyrrolidinyl)-3-oxopropyl]-dithio]- `
2-methylpropanoyl]-L-proline
By substituting 1,1'-[(sulfinylthio)-bis-(2-methyl-
3-propanoyl)~-bis-L-proline for the ethylthiosulfinate in
the procedure of Example 97, 1-[3-[[3-(2-carboxy-1-pyrro-
lidinyl)-3-oxopropyl]dithio]-2-methylpropanoyl]-L-proline
is obtained.
~ -64-
~Z;~37
Example 137
l,l'-[(Sulfonylthio)-bis-acetyi)-bis-L-hydroxyproline
sy substituting l,l'-(dithiobisacetyl)-bis-L-hy-
droxy proline for the l,l'-[dithiobis(3-propanoyl)-bis-L-
proline in the procedure of Example 127, l,l'-[(sulfonyl-
thio)-bis-acetyl)-bis-L-hydroxyproline is obtained.
Example 138
1,1'-[(Sulfonylthio)-bis-(3-propanoyl)]-bis-L-pipecollc
acid
By substituting 1,1'-[dithiobis(3-propanoyl)]-
bis--L-pipecolic acid for the 1,1'-[dithiobis(3-propanoyl)]-
bis-L-proline in the procedure of Example 127, l,l'-[(sul-
fonylthio)-bis-(3-propanoyl)]-bis-L-pipecolic acid is ob-
tained.
Example 139
1,1'-[(Sulfonylthio)-bis-(3-propanoyl)]-bis-5-hydroxy-L-
pipecolic acid
By substituting 1,1'-[dithiobis(3-propanoyl)]-bis-
5-hydroxy-L-pipecolic acid for the 1,1'-[dithiobis-(3-
propanoyl)]-bis-L-proline in the procedure of Example 1~7,
1,1'-[(sulfonylthio)-bis-(3-propanoyl)]-bis-5-hydroxy-L-
pipecolic acid is obtained.
Exam~le 140
1,1'-[(Sulfon_lthio)-bis-(2-methyl-3-propanoyl)_]-bis-L-
pipecolic acid
By substituting 1,1'-[dithiobis(2-methyl-3-propa-
noyl)]-bis-L-pipecolic acid for the 1,1'-[dithiobis(3-
propanoyl)]-bis-L-proline in the procedure of Example 127, ~ ; -
1,1'-[(sulfonylthio)-bis-(2-methyl-3-propanoyl)]-bis-L-
pipecolic acid is obtained.
,~ -65-
~Z33~
1,1'-[(Sulfonylthio)-bis-(2-benzyl-4-butanoyl)]-bis-L-
proline
-
By substituting 1,1l-[dithiobis(2-benzyl-4-butan-
onyl)~-bis-L-proline for the 1,1'-[dithiobis~3-propanoyl)]-
bis-L-proline in the procedure of Example 127, 1,1'-[(sul-
fonylthio)-bis-(2-benzyl 4-butanoyl)]-bis-L-proline is ob-
tained.
Example 142
3-Acetylthio-2-phenylpropanoic acid
By substituting 2-phenylacrylic acid for the meth-
acrylic acid in the procedure of Example 25, 3-acetylthio-
2-phenylpropanoic acid is obtained.
1-(3-Acetylthio-2-phenylpropanoyl)-L-proline tert-butyl ;~
ester
By substituting 3-acetylthio-2-phenylpropanoic acid
for the 3-acetylthio-2-methylpropanoic acid in the proce-
dure of Example 28, 1-(3-acetylthio-2-phenylpropanoyl)-L- ~ ~-
proline tert-butyl ester is obtained.
Example 143
1-(3-Mercapto-2-phenylpropanoyl)-L-proline
By substituting 1-(3-acetylthio-2-phenylpropanoyl)-
L-proline tert-butyl ester for the 1-(3-acetylthio-2-
methyl-propanoyl-L-proline tert-butyl ester in the pro-
cedure of Example 29, and subjecting the product to am-
monolysis as in Example 34, 1-(3-acetylthio-2-phenylpro-
panoyl)-L-proline and 1-(3-mercapto-2-phenylpropanoyl)-L-
proline are obtained.
-66-
,.
337
Example 144
1-[3-(Acetylthio)-DL-propanoyl]pipecolic acid
Pipecolic acid (6.5 g.) is suspended in 200 ml. of
dimethylacetamide. 3-ace-tylthiopropanoyl chloride (8.3 g.)
is added dropwise at 23 to the suspension. A clear solu-
tion forms and the te~perature rises to 28. To this clear
solution is added N-methylmorpholine (10.1 g.). An imme-
diate precipitate forms and the temperature rises to 34.
The mixture is heated on a steam bath for 1 hour when a
clear solution forms. On cooling, the precipitated solid
is filtered to yield 5.1 g. of 1-[3-(acetylthio)-DL-pro-
panoyl]pipecolic acid, m.p. 190-200. The solvent is re-
moved and the viscous residue is triturated with isopropyl
ether to yield 7.8 g. of product, m.p. 98-101. Xecrystal-
lization fxom acetone-hexane yields a constant melting
solidl m.p. 102-104; Rf 0.72 [silica gel, benzene, acetic
acid (7:2)]. `
Example 145
DL-1-(3-Mercaptopropanoyl)pipecolic acid
,
12 ml. of concentrated ammonium hydroxide is stirred
under nitrogen at 10 for about 15 minutes, then solid 1-
[3-(acetylthio)-DL-propanoyl]-pipecolic acid (6.6 g.) is
added at 5 to 10. A clear solution forms after 2-3 min-
utes. The ice bath is removed and the solution is stirred
at room temperature under nitrogen for 45 minutes. The
solution is made strongly acid with 20~ HCl (cooling) and
the precipitated oil is extracted with 3 x 150 ml. of ethyl
acetate. The ethyl acetate extracts are dried over magne-
sium sulfate and the solvent is removed to yield 6.0 g. of
DL-1-(3-mercaptopropanoyl)pipecolic acid, Rf 0.77 [silica
gel, benzene, acetic acid (7:1)].
-67-
,, ,
37
HA135b
_ample 146
1-(3-Mercaptopropanoyl)-L-pipecolic acid
By subs~ituting L-pipecolic acid for the DL- .
pipecolic acid in the procedure of Example 144 and then
submitting the product to the pxocedure of Example 145,
1-[3-(acetylthio)propanoyl]-L-pipecolic acid and 1-(3-
mercaptopropanoyl)-L-pipecolic acid Rf 0.80 [silica gel,
benzene, acetic acid (7~ , [~] -51.5 (c, 1.0 abs.
ethanol), are obtained.
Example 1~7
1-[3-(Acetylthio)-2-methylpropanoyl-DL-pipecolic acid
6.5 g. (0.05 m.) of pipecolic acid are suspended ;
in di~ethylacetamide (200 mg.), 9.0 y. ~0.05 m.) of
3-acetylthio-2-methylpropanoyl chloride is added dropwise.
The temperature rises to 29 and a clear solution forms. -
Then 10.1 g. of N-methylmorpholine is added all at once
and the temperature rises to 34. The mixture is heated
on a steam bath for 1 hour when a clear solution forms. ~-
This is allowed to stand at room temperature overnight
and the solid which precipitates is filtered to yield
6.1 g., m.p. 203-204 . The solvent is removed and the
viscous residue is triturated with water and 20% HCl. The ~` `
yellow oil is extracted with 3 x 150 ml. of ethyl acetate. ~ ~-
The ethyl acetate extracts are dried over magnesium suIfate
and removed to yield 14 g. of 1-[3-(acetylthio)-2-methyl-
propanoyl-DL-pipecolic acid as a viscous oil.
Example 148
1-(3-Mercapto-2-methylpropanoyl)-DL-pipecolic acid
Aqueous NH4OH (30 ml. water and 20 ml. conc. NH40H)
is stirred under nitrogen at 10 for 15 minutes. This is
6~-
37
HA135b
added to 13.0 g. (0:05 m) of 1-[3-(acetylthio)-2-
methylpropanoyl]-DL-pipecolic acid and the resulting solution
is stirred for 10 minutes under nitrogen; then at room
temperature for 50 minutes. It is then treated with water ~;
and 20% HCl and the yellow oil extracted with 3 x 150 ml.
of ethyl acetate. The ethyl acetate extract is dried over
magnesium sulfate and removed to yield 11.1 g. 1-(3-
mercapto-2-methylpropanoyl)-DL-pipecolic acid as a viscous
oil. Rf 0.62 [silica gel, benzene, acetic acid (7:2)]
~ Q~e 149
3-[(4-Methoxyphenyl)methylthio]-2 methylpropanoic acid
p-Methoxy--toluene thiol (15.4 g., 0.1 mol.) is
added to a solution of methacrylic acid (8.6 g., 0.1 mol.)
in 50 ml. 2N sodium hydroxide. The mixture is heated on --
the steam bath for three hours, then re~luxed for two
hours and cooled. The mixture is extracted with ether, then
the aqueous layer is acidified with concentrated HCl and
extracted with dichloromethane. The acidic extracts are
. ..
washed with brine, dried (MgSO4) and evaporated in vacuo.
The resulting semi-solid is taken up in 50 ml. of dichloro-
methane, diluted with 50 ml. hexane, and chilled. 3-1(4- ;~
methoxyphenyl)methylthio]-2-methylpropanoic acid is
collected as a white crystalline solid~ m.p. 74-82
(5.5 g.).
Example 150
1-[3-(4-Methoxyphenyl)-methylthio]-2-methylpropanoyl-L
proline tert-butyl ester
.
3-l(4-methoxyphenyl)methylthio]-2-methylpropanoic
acid (3.6 g., 0.015 mol.), L-proline tert-butyl ester
(2.6 g., 0.015 mol.), and dicyclohexylcarbodiimide (3.1 g.,
_fi9_
2~37`
HA135b
0.015 mol.) are di~solved in 50 ml. of dichloromethane
and stirred thirty minutes at 0 . The cooling bath is
removed and the mixture stirred overnight (sixteen hours).
The resulting suspension is filtered and the filtrate
washed with 5% potassium bisulfate, saturated sodium bicarbonate~
and brine, then dried (MgSO4) and evaporated in vacuo.
The resulting clear oil is applied to a 250 ml. silica ; ;-
gel column and chromatographed using 20% ethyl acetate/
hexane as eluant. The main fraction (R = 0.70, silica
f
gel, ethyl acetate) is evaporated to 5.5 g. (93%) of 1
[3-(4-methoxyphenyl)methylthio]-2-me*hylpropanoyl-L-proline
tert-butyl ester as a clear oil. Rf = 0.70 (silica gel, ~ ;
ethyl acetate); R~ - 0.60 (silica gel, ether).
Example 151
_(3-Mercapto-2-methylpropanoyl)-L-proline
The ester from Example~150 (1.2 g., 0.003 mol~
anisole (5 ml.) and trifluoromethanesulfonic acid (0.5 ml.)
are dissolved in 20 ml. of tri~luoroacetic acid-under
::
nitrogen, and the resulting red solution let stand one hour
at room temperature. The solution is evaporated in vacuo
to a red residue which is taken up in ethyl acetate and
washed with water, brlne, then dried (MgSO~) and evaporated.
The residue is repeatedly triturated with hexane and the
residual hexane evaporated; the oil residue amounts to
0.4 g. A portion (180 mg.) of this material is subjected
to preparative thin-layer chromatography on 2 mm silica gel ~-
plates using benzene/acetic acid 75:25 as eluant. The
- main nitroprusside-positive band (R~ = 0.40) is recovered,
affording 135 mg. of 1-(3-mercapto-2-methylpropanoyl)-L-
proline as an oil. TLC using benzene/acetic acid 75:25
-70-
HA135b
(Rf = 0.40) and chloroform/methanol/acetic acid 50:40:10
(Rf = 0.62).
E_ample 152
1-(3-Mercapto-2-D-methylpropanoyl)-L-proline
Under a blanket of argon 1-[3-(acetylthio)-2-
~methylpropanoyl]-L-proline (10.0 g.) is slurried in
water (lS0 ml.) at 10. To this mixture is added SN
sodium hydroxide and the pH of the solution maintained
at 13 for 1.5 hours. After this time, when the uptake
of sodium hydroxide had ceased, the solution is
acidified to a pH = 2.0 with concentrated sulfuric acid.
The aqueous solution is then extracted three
times with methylene chloride (3 x 150 ml.) and the
combined methylene chloride fractions concentrated to
an oil. The concentrate is taken up in ethyl acetate,
filtered and the filtrate diluted with hexane (30 ml.). ~ :
An additlonal amount of hexane is~added after 1/2 hour
and then the mixture coo~led to 10 for 1 hour. ~ -
The crystals are filtered and washed wlth hexane
. .
(2 x 25 ml.) and dried to constant weight to give
1-(3-mercapto-2-D-methylpropanoyl)-L-proline as white
crystals, 6.26 g., m.p. 1~00-102.
Example 153
1-[3-Tosyloxy-2-methylpropanoyl]-L-proline
By substituting 3-tosyloxy-2-methylpropanoic acid
chloride for the 3-acetylthio-2-methylpropanoic
acid chloride in the procedure of Example 29b 1-[3-
tosyloxy-2 methylpropanoyl]-L-proline is obtained. -~
-71-
,,
~Z~37 HA135b
Example 154
1-[3-Acetylthio-2-methylpropanoyl]-L-proline
1-[3-Tosyloxy-2-methylpropanoyl]-L-proline
(3.5 g.) is added to a solution of thiolacetic acid
(1.14 g.), and triethylamine (3.5 ml.) in ethyl acetate
(20 ml.). The solution is maintained at 50 for three
hours, cooled, diluted with ethyl acetate (100 ml.), and
washed with dilute hydrochloric acid. The organic layer
is dried and concentrated to dryness in vacuo. The
residue is dissolved in acetonitrile and dicyclohexylamine
is added. The crystalline precipitate is recrystallized
from isopropanol to yield l-[3-acetylthio-2-D-methyl-
propanoyl)-L-prollne, dicyclohexylamine salt, m.p. ;~
187-188 , [a]D -67 (c 1,4,~EtOa). This salt ls ~ -
converted to the free acid, m.p. 83-85 (an isomorphic ;~
form of m.p 104-105~ is obtained if the crystallizing
solution is seeded w1th high melting material)~. ~
Example 155 ; ~ -;
1-(3-M_rcaptopropanoyl)-L=proline, t-butyl ester ~ -~
~ To a stirred solution of~l.71 g. (10 mmoLes) of
; proline t-butyl ester and 1.35 g. (10 mmoles) of 1- ~~~
hydroxybenzotriazole hydrate in 20 ml. of N,N-dimethyl-
formamide a~t 0-S are added 2.06 g. (lO mmole) of N,N'-
dicyclohexylcarbodiimide. The mixture is stirred for
10 minutes, followed by the addition of 1~06 g. (10 mmole)
of 3 mercaptopropanoic acid in 2 ml. of N,N-dimethyl~
formamide The mixture is then stirred at 0-5 for
1 hour, and at room temperature overnight.
The precipitated N,N'-dicyclohexylurea is
filtered off, and the filtrate conccntrated in vacuo.
-72-
"' ' ' ' ' ' ' ' . , " '
~ 337 HA135b
The residue is taken up in ethyl acetate, washed
thoroughly with saturated aqueous sodium bicarbonate,
dried, a~d concentrated in vacuo to 2.5 g. of oil.
The oil is taken up in 1:1 ethyl acetate-hexane
and applied to a silica gel column (100 g.). Elution
with 1:1 ethyl acetate-hexane affords 1.40 g. (54~) o
1-(3-mercaptopropanoyl)-L-proline, t-butyl ester as an
oil, which crystallizes on standing. Recrystallization ~;
from ether-hexane yields 0.9 g. of colorless crystalline
solid, m.p. 55-60, identical to the compound of
Example 17.
Example 156 ~ ;
1-(3-Mercaptopropanoyl)-L-proline
A solution of 75 mg. (0.27 mmole) of 1-[3-[~(ethyl- -~ -
amino)carbonyl]thio]propanoyl]-L-proline in 1 ml. each of
concentrated ammonium hydroxide and water is allowed to
stand at room temperature for 18 hours under argon. The
solution is diluted with a small amount of water and ~ ;~
extracted with ether. The aqueous layer is acidified with
cold concentrated hydrochloric acid and extracted with
ethyl acetate. The combined extracts are dried and
concentrated in vacuo to give a compound identical with ;
the product of Example 18. TLC (silica gel; benzene:acetic
acid 7:3) Rf 0.4.
Example 157
Methacryloyl-L-Proline
L-proline (23.0 g., 0.2 mol.) is dissolved in
100 ml. water and stirred in an ice bath. Methacryloyl
chloride (19.6 ml~, 0.2 mol.) in 25 ml. of methyl isobutyl
ketone is added dropwise over three hours. Sodium hydroxide
73-
~.
~2~ ?~37 ~: -
solution (2N) is added simultaneously, maintaining the pH -
of the reac-tion mixture at 7Ø Addition of base is con- -
tinued for four houxs after addition of acid chloride has
been completed. The reaction mixture is adjusted to pH 5
with concentrated HCl and extracted wi-th ethyl acetate.
The aqueous layer is then acidified to pH 2.5 and extracted
thoroughly with ethyl acetate. The acidic extracts are
washed with brine and dried (MgSO4). The ethyl acetate
solution is treated with dicyclohexylamine (40 ml.) and
chilled overnight. The resulting white precipitate is
filtered and dried, yielding 29 g. (39%) of white solid
m.p. 202-210. The solid is crystallized from 1.5 liters
3:1 acetonitrile/isopropanol to yield 19.7 g. of metha-
cryloyl-L-proline, dicyclohexylamine salt as fine white
needles, m.p. 202-210.
The salt is dissolved in water/ethyl acetate and ;
the mixture acidified with concentrated HCl. The result-
ing suspension is filtered to remove a fine white preci-
: ,-.
pitate which is washed well with ethyl acetate. The fil- `~
trate is saturated with sodium chloride and extracted ~
thoroughly with ethyl acetate. The extracts are washed ~;
with brine, dried (MgSO4) and evaporated to a clear oil
which solidifies. Crystallization from ethyl acetate/hex-
ane yields 7 5 g. (83%) of methacryloyl-L-proline as a
white crystalline solid, m.p. 89-93. An analytical ;~
sample is obtained by recrystallization, m.p. 95-98.
Example 158
1-(3-Acetylthio-2-D-methylpropanoyl)-L-proline
Methacryloyl-L-proline (183 mg., 0.0001 mol.) is
dissolved in thiolacetic acid (0.5 ml.) and allowed
-74-
,~
2337
HA135b
to stand at room temperature for sixteen hours. The
solution is evaporated in vacuo to a yellow residue.
Preparative thin layer chromatography (silica gel, di-
chloromethane/methanol/acetic acid 90:5:5) allows isolation
of a clear oil (2fiO rng.) as the main fraction. TLC (dichloro-
methane/methanol/acetic acid 90:5:5) shows this material
to be l-(3-acetylthio-2-DL-methylpropanoyl)-L-proline
corresponding to the product of Example 29B. Rf = 0.35; ~
(benzene/acetic acid 75:25) Rf = 0.38. ;
The oil is dissolved in 3 ml. acetonitrile,
treated with dicyclohexylamine until the solution is ~ -
basic, and chilled. A white crystalline solid (106 mg.)
m.p. 175-181 , is collected. Crystallization from
isopropanol gives l-(3-acetylthio-2-D-methylpropanoyl)~
L-proline, dicyclohexylamlne salt, m.p. 187-18~8 ,
identical with this product in Example 29A.
Example 159
: ~
: 1- [Dithiobis- (2-methyl-3-propanoyl)]-bis-L-pro~ine
By substituting 3,3'-dithiobis-2-methylpropanoic acid
for the 3-acetylthio-2-methylpropanoic acid in the pro- ~ -
cedure of Example 29B, l-[dithiobis-(2-methyl-3-propanoyl)]-
;:~ ::-
bis~L-proline is obtained.
Example 160
1-(3-Mer apto-2 - methylpropanoyl)-L-proline
Zinc dust (10.0 g.) is added to a slurry of the
product of Example 159 (5.0 g.) in 100 ml. of l.O.N
sulfuric acid and the mixture is stirred at 18 for four
hours under a blanket of nitrogen. The solution is then
filtered, the zinc washed with wat3r (20 ml.) and the
combi~led filtrates are extracted with methylene chloride
-75-
,
~2,~3~
HA135b ~ ~
.
(3 x 75 ml.)O The methylene chloride washes are back
extracted with water (25 ml.) and then the organic
solution concentrated to an oil. This oil is taken up
in ethyl acetate (20 ml.) and filtered. Hexane (15 ml.)
is added to the filtrate and the mixture is stirred for
15 minutes. After this time, an additional volume of
hexane (30 ml.) is added and the solution cooled to 5 ~-
for 1 hour. The mixture is then filtered, and the product ~
i5 washed with hexane (2 x 10 rnl.) and dried to give 4.17 g. ~'
of white crystals of the product, 1-(3-mercapto-2-
methylpropanoyl)-L-proline. TLC, Rf = 0.60
(Solvent system benzene/acetic acid 75:25).
Example 161
3-Benzvlthio-2-methylpropanoic acid
- : - .
By substituting a-toluenethiol for p-methoxy-a- ;~
,
toluenethiol in the procedure of Example 149, 3~-benzylthio-2-
methylpropanoic acid is obtained.
~ Example 162
1-[3-(Benzylthio)-2-methylpropanoyl]-L-proline ~ert.
butyl ester
By sub~tituting 3-benzylthio-2-methylpropanoic
acid for the 3-[(4-methoxyphenyl)methylthio]-2-methyl-
propanoic acid in the procedure of Example lS0, 1-13
~benzylthio)-2-methylpropanoyl]-L-proline tert. butyl ester
i5 obtained, ~ ;
Exa ~ ~.
1-[3-(Benzylthio)-2-methylpropanoyl]-L-proli.ne
1-~3-(benzylthio),-2-methylpropanoyl]-L-proline
tert. butyl ester (7.8 g.) is dissolved in a mixture of
anisole (55 ml.) and trifluoroacetic acid ~110 ml.). After
-76-
37
HA135b
one hour storage at room temperature, the solvent is
removed in vacuo and the residue is dissolved in ether,
washed several times with saturated sodium chloride, dried
over magnesium sulfate and evaporated to dryness in vacuo
to yield l-[3-(benzylthio)-2-methylpropanoyl]-L-proline.
Rf 0.5 (Silica gel, Benzene/acetic acid 3:1) Rf 0.5.
(Silica gel, Methyl ethylketone/acetic acid/pyridine/water
14:1:2:1). -
Example 164
1-(3-Mercapto-2-methylpropanoyl)-L-proline
l-[3-(ben2ylthio)-2-methylpropanoyl]-L-proline
(0.1 g.) is suspended in boiling liquid ammonia (10 ml.)
and small pieces o~ sodium are added with stirring until
persistent blue color. The color is discharged with a
few crystals of ammonium sulfate and the ammonia is allowed
to evaporate under a current of nitrogen. The residue is
dissolved in a mixture of dilute hydrochloric acid and ethyl
acetate. The organic layer is dried and concentrated to
dryness in vacuo to yield l-(3-mercapto-2-methylpropanoyl)- ;~
L-proline. Rf: 0.35 (Silica gel; Benzene/acetic acid
3:1), R~ 0.5 (Silica gel; ~ethyl-ethylketone/acetic acid~
pyridine/water 14:1:2:1) identical to the compound of
Example 34.
Example 165
3-Triphenylmethylthio-2-methylpropanoic acid
A solution oE 3-mercapto-2-methylpropanoic acid
(1.2 g.) and tritylchloride (2.9 g.) in methylene
chloride (50 ml.) is kept at room temperature for 2 hours.
The mixture is warmed in a steam bath for 20 minutes and then
evaporated to dryness in vacuo and the residue is dissolved
-77-
~ Z~37 HA135b
in saturated aqueous sodium bicarbonate and the solution
is washed with ethyl acetate. The aqueous phase is
acidified to pH 3 and extracted with ethyl acetate. The
organic layer is dried and concentrated to dryness to give
3-triphenylmethylthio-2-methylpropanoic acid. Rf 0.8
(Silica gel, Benzene/acetic acid 3
Example 166
:
1-[3-(Triphenylmethylthio)-2-methylpropanoyl]-L-proline
tert.butyl ester
By substituting 3-triphenylmethylthio-2-methyl-
propanoic acid for the 3-[(4-methoxyphenyl)methylthio]- ~ ~
2-methylpropanoic acid in the procedure of Example 150, ~ -
1-[3-(txiphenylmethylthio)-2-methylpropanoyl]-L-proline
tert.butyl ester is obtained.
Example 167
1-[3-~Triphenylmethylthio)-2-methylpropanoyl]~L-proline
3-Triphenylmethylthio-2-methylpropanoic acid
(1.8 g.) and N,N'-carbonyldiimidazole (0.8 g.) are
dissolved in tetrahydrofuran (10 ml.) with stirring at
room temperature. Aeter twenty minutes, the solution is ~ ;
added to a mixture of L-proline (0.6 g.) and N-methyl-
morpholine (1 g.) in dimethylacetamide (20 ml.). The
resulting mixture is stlrred overnight at room temperature,
concentrated to dryness and the residue dissolved in a -
mixture of ethyl acetate and 10% aqueous potassium bisulfate.
The organic layer is separated and dried and concentrated
t~ dryness in vacuo to obtain 1~[3-(triphenylmethylthio)-
2-methylpropanoyl]-L-proline. Rf: = 0.4 (~ilica gel,
Benzene/acetic acid 3:1), R~ 1.0 (Silica gel, Methyl-ethyl-
ketone/acetic acid~pyridine/water 14:1:2:1).
-78-
~ 37 HA135b
Example 168
1 [3 Mercapto-2-methylpropanoyl)-L-proline
1-[3-(triphenylmethylthio)-2-methylpropanoyl]-L-
proline tert.butyl ester (5 g.) is dissolved in a mixture
of anisole (55 ml.) and trifluoroacetic acid (110 ml.).
After one hour storage at room temperature, the solvents
are removed in vacuo and the residue is applied to a
column of silica gel equilibrated with benzene:acetic
acid (75:25) and eluted with the same solvent. The
fractions coxresponding to the component with Rf 0.40
(TLC silica gel with same system) are pooled and concentrated
to dryness to yield l-~3-mercapto-2-methylpropanoyl)-L-
proline. Rf 0.62 (silica gel, chloroform/methanol~
, - .
acetic acid:water 50:40:10), identical to the compound
of Example 34.
xampIe 169
3-(Tetrahydropyran-2-ylthlo)-2-methylpropanoic acid
To a solution of 3-mercapto-2-methylpropanoic ~ ~
- -' -, .
acid (2.4 g.) and freshly distillled 2,3-dihydro-4H-
pyrane (1.9 g.) in benzene (60 ml.), boron trifluoride
etherate ~2.8 g.) is added. A~ter two hours, potassium
carbonate (4 g.) is added, the mixture is stirred and
filtered. The filtrate is concentrated to dryness to
yield 3-(tetrahydropyran-2-ylthio)~2-methylpropanoic acid.
Example 170 ~ ;~
1-~3~(T_trahydropyran~2~ylthio)~2~methylpropanoyl]-L-proline
By substituting 3-(tetrahydropyran-2-ylthio)~2~
methylpropanoic acid for the 3-triphenylmethylthio~2-
methylpropanoic acid in the procedure of Example 167,
1-[3-(tetrahydropyran-2-ylthio)~2-methylpropanoyl]-L-proline
-79-
3L~fQZ;~37
HA135b
is obtained~ Rf: 0.8 (Silica gel~ Benzene/acetic acid
3:1; R~: 0.75 (Silica gel, Methyl-ethylketone/Acetic acid/
pyridine/water; 14:1:2:1).
Example 171
1-(3-Mercapto-2-methylpropanoyl)-L-proline
A solution of 1-[3-(tetrahydropyran-2-ylthio)-2-
methylpropanoyl)-L-proline (1 g.) in a mixture of methanol
(25 ml.) and concentrated hydrochloric acid (25 ml.) is- ~ ~-
stored at room temperature for 30 minutes. The solvents
are removed in vacuo to yield 1-(3~mercapto-2-methyl-
propanoyl)-L-proline. Rf: 0.35 (silica gel, Benzene/
acetic acid, 3:1), Rf 0.5 (silica gel, Methyl-ethylketone/
acetic acid/pyridine/water 14:1:2:1) identical to ~he -~
compound of Example 34.
. ~:
Example 172
3-Acetamidomethylthio-2-methylpropanoic acid -
3-Mercapto-2-methylpropanoic acid (2.4 g.) and
N-hydroxymethylacetamide (1.8 g.) are dissolved in ~ ;
trifluoroacetic acld and the solution is stored at room
temperature for one hour. The trifluoroacetic acid is
removed in vacuo and the residue is dried in vacuo over
potassium hydroxide to yield 3-acetamidomethylthio-2- - ;
~: :
methylpropanoic acid.
Example 173
1-[3-(Acetamidomethylthio)-2-methylpropanoyl]-L-proline
By substituting 3-acetamidomethylthio-2-methyl-
propanoic acid for the 3-(tetrahydropyran-2-yl thio)-2-
methylpropanoic acid in the procedure of Example 170
1-[3-(acetamido~ethylthio)-2- ;
~
21337
HA135b
methylpropanoyl]-L-proline is obtained. Rf 0.2 (Silica
gel, Benzene/acetic acid 3~1) Rf 0.3 (Silica gel, Methyl-
ethylketone/acetic acid/pyridine/water 14:1:2:1).
Example l_
1-(3-Mercapto-2-methylpropanoyl)-L-proline
-
1-[3-(acetamidomethylthio)-2-methylpropanoyl~-L-
- proline (1.4 g.) and mercuric acetate (1.93 g.) are dissolved
in a mixture of acetic acid (25 ml ) and water (25 ml.).
After one hour stirring on the steam bath, hydrogen sulfide -~
is bubbled through until no more precipitation of mercuric
sulfide is observed. The mixture is filterd, the precipitate
is washed with ethanol, and the filtrate is concentrated
to dryness in vacuo to yield l-(3-mercapto-2-methylpropanoyl)-
L-proline. Rf: 0.35 (Silica gel, Benzene/Acetic acid 3:1);
Rf : 0.5 (Silica gel, Methyl-ethylketone/Acetic acid/ :
- :~
pyridine/water 14:1:2:1) identical to the compound of
Example 34.
Example 1i5
1-(3-Mercapto-2-methylpropanoyl)-L-proline tert. butyl ester
To the cold (5) solution of 1.2 g. (10 mMol.) of 3_
mercapto-2-methylpropanoic acid and 1.7 g. (10 mMol.) of
L-proline tert. butyl ester in 25 ml. dichloromethane
2.26 g. of dicyclohexylcarbodiimide in 5 ml. dichloromethane
is added in portions. After 2 hours at room temperature,
5 drops of acetic acid are added, the mixture is filtered
and thé filtrate evaporated to an oily residue. This
residue is taken up in 20 ml. of petroleum ether-ethyl
acetate ~3:1) and applied to a 150 ml. silica gel column
prepared in petroleum ether. The fraction eluted with
petroleum ether-ethyl acetate (1:1) contains the product,
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HA135b
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1-(3-mercapto-2~methylpropanoyl)-L-proline tert.butyl ester.
This fraction (0.6 g.) is dried over P2O5 in vacuo for
12 hours. Rf 0.6 (Silica gel, Benzene/Acetic acid 3:1),
Rf 0.8 (Sillca gel, Methyl-ethylketone/acetic acid/pyridine/
water 14:1:2:1). ;
Example 176 -
1-(3-Mercapto-2-methylpropanoyl)-L-proline
By substituting 1-(3-mercapto-2 methylpropanoyl)-L-
proline tert. butyl ester for the l-(3-mercaptopropanoyl-L-
proline tert.butyl ester in the procedure of Example 18C,
1-(3-mercapto-2-methylpropanoyl)-L-proline is obtained.
Rf 0.35 ~Silica gel, Benzene/acetic acid 3:1), Rf 0.5 ;~
(Silica gel, Methyl-ethylketone/Acetic acid/Pyridine/Water
14:1:2:1), identical to the compound of Example 34.
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233'7
The racemic form of the final product in any of the
foregoing examples is produced by utilizing the DL-form
of the s-tarting amino acid instead of the L-form.
Similarly, the D-form of the final products in any
of the foregoing examples is produced by utilizing the D-
form oE the starting amino acid instead of the L-form.
Example 177
1000 tablets each containing 100 mg~ of l-(2-mer-
captopropanoyl)-L-proline are produced from the following
ingredients:
l-(2-Mercaptopropanoyl)-L-proline100 g.
Corn starch 50 g.
Gelatin 7.5 g.
Avicel (microcrystalline cellulose) 25 g- -
Magnesium stearate 2.5 g.
The l-(2-mercaptopropanoyl)-L-proline and corn
starch are admixed with an aqueous solution of the gelatin.
The mixture is dried and ground to a fine powder. The
Avicel and then the magnesium stearate are admixed with
the granulation. This is then compressed in a tablet to
form 1000 tablets each containing 100 mg. of active ingre- ~
dient. ~;
Example 178 ;~
By substituting 100 g. of l-(3-mercapto-2-D~methyl- ~;
propanoyl)-L-proline for the 1-(2-mercaptopropanoyl)-L-
proline in Example 177, 1000 tablets each containing 100
mg. of the l-(3-mercapto-2-D-methylpropanoyl-L~proline
are produced.
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337
Example 179
1000 tablets each containing 200 mg. of 1-~2-
mercaptoacetyl)-L-proline are produced from the following
ingredients:
1-(2-ilercaptoacetyl)-L-proline 200 g.
Lactose 100 g.
Avicel 150 g.
Corn starch 50 g.
Magnesium stearate 5 g.
The 1-(2-mercaptoacetyl)-L-proline, lactose and
Avicel are admixed, then blended with the corn starch.
Magnesium stearate is added. The dry mixture is compressed ,
in a tablet press to form 1000 505 mg. tablets each containlng
200 mg. of active ingredient. The tablets are coated ~/ith a
solution of Methocel E 15 (methyl cellulose) including as a
color a lake containing yellow ~6. ;
Example 180 ;
Two piece ~11 gelatin capsules each containing 250 mg.
of 1-(2-mereaptopropanoyl)-L-proline are filled with a mixture
of the following ingredients:
1-(2-Mercaptopropanoyl)-L-proline 250 mc3.
Magnesium stearate 7 mg.
USP lactose 193 mc3.
Example 181
- An injectable solution is produced as follows:
1~(2-Mercaptopropanoyl)-L-proline500 mg.
.
Methyl paraben 5 g.
Propyl paraben 1 g.
Sodiurn ehloride 25 g.
Water for injec~iol) ~s. 5 1.
, ~8~-
~I~Z337 HA135b
The active substance, preservatives and sodium
chloride are dissolved in 3 liters of water for injection and
then the volume is brought up to S liters. The solution is
filtered -through a sterile filter and aseptically filled
into presterilized vials which are then closed with pre-
sterili~ed rubber closures. Each vial contains 5 ml. of
solution in a concentration of 100 rng. of active lngredient
per ml. of solution for injection.
Example 182
By substituting 100 g. of 1,1'-[dithiobis(2--D-methyl- ~
3-propanoyl)]-bis-L-proline Lor the 1-(2-mercaptopropanoyl)- ~;
L-proline in Example 177, 1~00 tablets each containing 100 mg.
of the l,l'-[dithiobis[2-D-methyl-3-propanoyl)]-bis-L-
proline are produced. ~-
Each of the products of the examples can be
similarly formulated by substituting it for the active
ingredient in Examples 177, 179, 180 or 181.
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