Note: Descriptions are shown in the official language in which they were submitted.
~ 169a
--1--
MERCAPTOACYL DERIVATIVES OF SUBSTITUTED ~ROLINES
This invention relates to new ether and thio-
ether mercaptoacyl prolines of the formula
(I)
X-R
R3 lR2 H2C5~
R4- S - (CH)n CH - CO N -C*- COOR
H
wherein the group X-Rl is located at the 3- or 4-
position in the ring;
X is oxygen or sulfur;
lS R is hydrogen or lower alkyl;
Rl is lower alkyl, lower alkenyl, lower
alkynyl, phenyl, substituted phenyl, phenyl-lower
alkylene or substituted phenyl-lower alkylene;
R2 and R3 are independently selected from
hydrogen, lower alkyl, and trifluoromethyl;
R4 is hydrogen, R5-CO- or
X-R
IR3 lR2 H2C ~
-S-(CH)n CH - CO -- N - C*- COOR
H
'' ~
~ 4~ HA169a
--2--
R5 is lower alkyl, phenyl, or phcnyl-lower
alkylene;
n is 0, 1 or 2;
and salts thereof.
.
The invention in its broadest aspects relates
to the ether and thioether mercaptoacyl prolines
having formula I above, to compositions containing
such compounds and to the method for using such
compounds as anti-hypertensive agents.
The term lower alkyl as used in defining the
symbols R, Rl, R2 and R3 are straight or branched
chain hydrocarbon radicals having up to seven carbons,
for example, methyl, ethyl, propyl, isopropyl, butyl,
isobutyl, t-butyl, pentyl, isopentyl, etc. The
preferred lower alkyl groups are up to four carbons
with methyl and ethyl being most preferred.
The term lower alkenyl as used in defining
the symbol Rl are mono~unsaturated straight or branched
chain hydrocarbon groups of from 2 to 7 carbons
such as ethenyl, propenyl, isopropenyl, butenyl, and
the like. The lower alk~ynyl groups are straight or
branched chain hydrocarbon groups of from 2 to 7
carbons having one triple bond, e.g., propargyl.
The preferred lower alkenyl groups are from 2 to 5
carbons and the preferred lower alkynyl groups are
from 3 to 4 carbon atoms.
The term substituted phenyl and substituted
phenyl-lower alkylene as used in defining the
~4~3~ 169a
-3 ~
symbol Rl include one or two, preferably one,
substitutents on the phenyl ring. Suitable substi-
tuents include lower alkyl groups of l to 4 carbons,
especially methyl, lower alkoxy groups of l to 4
carbons, especially methoxy, lower alkylthio groups
of l to 4 carbons, especially methylthio, halogens,
especially chloro or fluoro, trifluoromethyl, acetyloxy,
and hydroxy. The hydroxy substituted phenyl and
phenyl-lower alkylenes are obtained by hydrolysis of
the corresponding acetyloxy substituted phenyl compound
as the last step of the synthetic procedure.
The term halogen includes the four common
members, i.e., chloro, bromo, fluoro, and iodo, with
chloro, bromo, and fluoro being preferred.
The term phenyl-lower alkylene as used in
defining the symbols Rl and R5 include groups such
as ( 2 m ~ wherein m is an integer from
l to 4. Preferred phenyl-lower alkylene groups are
phenylmethyl and phenylethyl, especially phenylmethyl.
The lower alkanoyl groups represented by
R5-CO- are those having the acyl radicals of the
lower tC2-C7) fatty acids, for example, acetyl,
propionyl, butyryl, isobutyryl, and the like. The
lower alkanoyl groups having up to four carbons are
preferred with acetyl being especially preferred.
Similarly, when R5 in the group R5-CO- is phenyl-
lower alkylene, benzoyl is especially preferred.
The asterisk in formula I indicates an
asymmetr1c center which is present in the proline
~ 3~ 169~
ring. Of course, an additional asymmetric center can
be present in the mercapto sidechain depending upon
the substituents R2 and R3. The products of formula
I accordingly exist in stereoisomeric forms or
as racemic mixtures thereof. All of these are
within the scope of the invention. The synthesis
described below can utilize the racemate or one
of the enantiomers as starting materials. When the
racemic starting material is used in the synthesis
procedure, the stereoisomers obtained in the final
product can be separated by conventional chromatogra-
phic or fractional crystallization methods. The
X-Rl group also gives rise to cis-trans isomerism.
Preferably the asymmetric center in the
proline ring is in the L-configuration and if there
is an asymmetric center in the mercaptoacyl sidechain
it is in the D-configuration.
Preferred compounds of formula I are those
wherein R is hydrogen; Rl is lower alkyl of l to 3
carbons or wherein p is zero, l or
- (CH2 ) P~R6
2, and R6 is hydrogen, methyl, methoxy, methylthio,
chloro, fluoro, trifluoromethyl or hydroxy; R2
is hydrogen, methyl or trifluoromethyl; R3
is hydrogen; n is zero or one; and R4 is hydrogen.
Also preferred as intermediates are the above
compounds wherein R4 is acetyl or benzoyl, especially
acetyl.
Most preferred are the above compounds wherein
X is oxygen; Rl is methyl or ethyl, especially
~4.~930 HA169a
_5_
methyl; n is l; R2 is hydrogen or methyl, especially
methyl; R3 is hydrogen; R4 is hydrogen; and the
-XRl group is at the 4-position of the proline
ring, especially wherein the -XRl yroup is in the
S cis configuration.
The ethers and thioethers of Formula I are
obtained by coupling the ether or thioether proline
of the formula
(II)
HN * CooR
H
with an acid or its chemical equivalent of the formula
(III)
R3 R2
R'4-S-(CH)n_ CH-COOH
wherein R4 is hydrogen or R5-CO-, to yield the
product of the formula
~ 30 IIAlG9a
(IV)
XR
R3 R2 H2C
R4-S-(CH)n CH-CO - N-- C*- COOR .
H
This reaction can be effected in the presence
of a coupling agent like dicyclohexylcarbodiimide
or the like, or the acid can be activated by
formation of its mixed anhydride, symmetrical
anhydride, acid halide, active ester or use of
Woodward reagent K, N-ethoxycarbonyl-2-
ethoxy-1,2-dihydroquinoline or the like.
For a review of the methods of acylation,
see Methoden der Organishchen Chemie (Houben-
Weyl), Vol. XV, part II, page 1 et seq.
(1974). Preferably, the acid halide,
especially the acid chloride, of formula
III is reacted with the acid of formula II.
The ester compounds of formula IV, i.e.,
R is alkyl, can be converted to ~e free acid, i.e.,
R is hydrogen, by conventional means. For example,
if R is t-butyl treatment with trifluoroacetic acid
and anisole gives the free acid.
~ 3~ HA169a
--7--
The product of formula IV is preferably
isolated and purified by crystallization, e.g.,
by forming the dicyclohexylamine salt and then con-
verting the salt to the free acid form by treatment
with an aqueous solution of an acid, such as
potassium acid sulfate.
The product of formula IV bearing the acyl
group R5-CO- can be converted to the products of
formula I wherein R4 is hydrogen by conventional
hydrolysis or by ammonolysis.
The products of formula I wherein R4 is
IR3 lR2 21 ~3 1
-S-(CEI) - C~l - CO --N_ C*- COOH
are obtained by directly oxidizing with iodine a
product of formula I wherein R4 is hydrogen.
The esters of formula I wherein R is lower
alkyl can be obtained from the carboxylic acid
compounds, i.e., wherein R is hydrogen, by conventional
esterification procedures, e.g., by esterification
with a diazoalkane like diazomethane, 1-alkyl-3-p-
tolyltriazene, like l-n-butyl-3-p-tolyltriazene, or
the like.
The proline reactants of formula II can be
prepared by various means. For example, a hydroxy or
mercapto proline of the formula
~ 4~3~ 169a
--8--
(V) XH
2C ~
HN C*COOH
H
is acylated with an acylating agent such as acetic
anhydride, acetyl chloride, propionic anhydride,
butyric anhydride, benzylchloroformate, or the
like, so as to protect the nitrogen. The Rl
group is then introduced by reacting the N-protected
form of the compound of formula V with a halide,
Rl-hal, wherein hal represents a halogen, preferably
iodine, in the presence of silver oxide, sodium
hydride, sodium hydroxide or the like, to obtain
the intermediate having the formula
(VI)
H 2 C ~><
protected-N - C*- COORl
Alkaline hydrolysis of the intermediate of formula VI
with a base such as barium hydroxide, sodium hydroxide,
potassium hydroxide or the like first yields the
free acid (COOH~ and then hydrolysis with a mineral
acid, such as sulfuric acid, yields the starting
material of formula II.
Another method for preparing the proline
reactants of formula II is by treating the N-
protected tosyloxy proline ester, preferably the methyl
~14~3~ HA169a
ester of the formula
(VII)
OTsH2,C ~ ~
S
protected-N C*COOalkyl
with the sodium salt of the formula
(VIII)
10Rl-X-Na
to yield the intermediate of the formula
(IX)
H2C />~Rl
1 1
protected-N ~ C*- COOalkyl
H /~~\
In formula VII the symbol Ts represents -SO2 ~ ~r CH3
and the N-protecting group is benzyloxycarbonyl,
which is preferred, or other commonly employed acyl
protecting groups. In this reaction, if the tosylate
group is in the cis configuration the XRl group will
be in the trans configuration and if the tosyloxy
group is in the trans configuration the XR1 group
will be in the cis configuration. The intermediate
of formula IX is then treated to remove the alkyl
ester group and is then reacted with hydrogen bromide
to yield the HBr salt of the proline reactant of
formula II which can then be coupled with the acid,
~ 330 HA169a
--10--
preferably the acid chloride, of formula III.
The proline starting materials of Eormula II
wherein X is sulfur and the XRl group is attached at
the 3-position of the proline can also be obtained
by treating a 1,2-dehydroproline ester, preferably the
t-butyl ester, of the formula
(X)
r 1
N -- 1 COOalkyl
with an acylating agent such as benzyl chloroformate,
acetyl chloride, etc., to yield the 4,5-dehydro
compound
(XI)
~
protected-N -~ - COOalkyl
which is then reacted with the mercaptan Rl-SH
to yield
(XII)
~ S-R
protected-N COOalkyl
wherein the -S-Rl substituent is in the trans confi-
guration. The N-protecting and alkyl groups are then
removed to yield the desired starting material.
The proline starting materials of formula II
where Rl is phenyl, substituted phenyl, phenyl-
lower alkylene or substituted phenyl-lower alkylene
can also be obtained by treating the benzyl ester
~ 30 1iA169a
of the N-protected proline of formula V with the
alcohol Rl-OH in the presence of triphenylphosphine
and diethylazodicarboxylate according to the pro-
cedure of sittner et al., Chemistry and Industry,
15 March 1975, page 281. Removal of the N-protecting
group and the benzyl ester group yields the starting
material of formula II.
Reference is also made to the following
publications for additional illustrative information
with respect to the production of starting materials
and intermediates: Ondetti et al., U.S. Patents
4,046,889, 4,105,776, and 4,154,935; Neuberger,
J. Chem. Soc., 1945, p. 429-432; Patchett et al.,
J. Amer. Chem. Soc. 79, p. 185-192 (1957); Baer et
al., Can. J. Biochem. and Phys., 37, p. 583-587 (1959);
Sheehan et al., J. Amer. Chem. Soc. 85, p~ 3863-3865
(1963); Magerlein, J. Med. Chem. 10, p. 1161-1163
(1967). The procedures illustrated therein can be
utilized as general methods for the synthesis and
stereoconversion of compounds utilizable in the
invention of this application.
Additional experimental details are found in
the examples which are preferred embodiments and
also serve as models for the preparation of other
members of the group.
The compounds of this invention form basic
salts with a variety of inorganic or organic bases.
The salt forming ion derived from such bases can be
metal ions, e.g., aluminum, alkali metal ions,
such as sodium or potassium, alkaline earth metal
3 3V 1~1~16 9 a
-12-
ions such as calcium or magnesium, or an amine salt
ion, of which a number are known for this purpose,
for example, aralkylamines like, dibenzylamine, N,N-
dibenzylethylenediamine, lower alkylamines like
methylamine, t-butylamine, procaine, lower alkyl-
piperidines like N-ethylpiperidine, cycloalkylamines
like cyclohexylamine or dicyclohexylamine, l-adaman-
tanamine, benzathine, or salts derived from amino acids
like arginine, lysine or the like. The physiologically
acceptable salts like the sodium or potassium salts
can be used medicinally as described below and are
preferred. These and other salts which are not
necessarily physiologically acceptable are useful in
isolating or purifying a product acceptable for the
purposes described below, as illustrated with the
dicyclohexylamine salt and the cyclohexylamine salt in
the examples. The salts are produced by reacting
the acid form of the compound with an equivalent of
the base supplying the desired basic ion in a medium
in which the salt precipitates or in aqueous
medium and then lyophilizing. The free acid form can
be obtained from the salt by conventional neutraliza-
tion techniques, e.g., with potassium bisulfate, hydro-
chloric acid, etc.
The compounds of this invention inhibit the
conversion of the decapeptide angiotensin I to
angiotensin II and therefore are useful in reducing
~4.~0 HA169a
-13-
or relieving hypertension. The compounds of this
invention intervene in the renin -~ angiotensinogen -~
angiotensin I ~ angiotensin II sequence by
inhibitiny angiotensin converting enzyme and
reducing or eliminating the formation of the pressor
substance angiotensin II. Thus by administration
of a hypotensively effective amount of a composition
containing one or a combination of compounds of
formula I or physiologically acceptable salt thereof,
hypertension in the species of mammal suffering
therefrom is reduced or alleviated.
A single dose, or preferably two to four divided
daily doses, provided in a basis of about 0.1 to about
100 mg. per kilogram per day, preferably about 1
to about 50 mg. per kilogram per day,is appropriate to
reduce blood pressure as indicated in the animal
model experiments described by S. L. Engel,
T. R. Schaeffer, M. H. Waugh and B. Rubin,
Proc. Soc. Exp. Biol. Med. 143, 483 (1973).
The substance is preferably administered orally,
but parenteral routes such as subcutaneously,
intramuscularly, intravenously or intraperitoneally
can also be employed.
The compounds of this invention can be
utilized to achieve the reduction of blood pressure
by formulating in compositions such as tablets,
capsules or elixirs for oral administration or in
sterile solutions or suspensions for parenteral
administration. About 10 to about 500 m~. of a
compound or mixture of compounds of formula I or
physiologically acceptable salt is compounded
with a physiologically acceptable vehicle, carrier,
O 1U~1.69a
-14-
excipient, binder, preservative, stabilizer, flavor,
etc., in a ur.it dosage form as called for by accepted
pharmaceutical practice. The amount of active
substance in these compositions or preparations is
such that suitable dosage in the range indicated
is obtained.
Illustrative of the adjuvants which may be
incorporated in tablets, capsules and the like are
the following: a binder such as gum tragacanth,
acacia, corn starch or gelatin; an excipient such
as dicalcium phosphate or microcrystalline cellulose;
a disintegrating agent such as corn starch, potato
starch, alginic acid and the like; a lubricant such
as magnesium stearate; a sweetening agent such as
sucrose, lactose or saccharin; a flavoring agent
such as peppermint, oil of wintergreen or cherry.
When the dosage unit form is a capsule, it may
contain in addition to materials of the above
type a liquid carrier such as a fatty oil. Various
other materials may b epresent as coatings or to
otherwise modify the physical form of the dosage
unit. For instance, tablets may be coated with
shellac, sugar or both- A 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 orange flavor.
Sterile compositions for injection can be
formulated 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.
~ ~ 4~3~ ~169a
--15--
The following examples are illustrative of
the invention and constitute preferred embodiments.
They also serve as models for the preparation of
other members of the group which can be produced
by replacement of the given reactants with suitably
substituted analogs. A11 temperatures are in degrees
Celsius.
~ 3V HA169a
-16-
Example 1
1-(3-Acetylthio-l-oxopropyl)-trans-4-methoxy-L-proline
a) N-Acetyl-trans-4-hydroxy-L-proline
A stirred suspension of 26.2 g. (0.2 mole) of
trans-4-hydroxy-L-proline in 400 ml. of acetic acid
is treated with 26 ml. of acetic anhydride. The
solid gradually dissolves after 2 hours of stirring
at room temperature. The solution is transferred to
a 2 liter flask and the solvent is removed on a
rotary evaporator at a bath temperature of 45.
The syrupy residue (57.5 g.) is diluted with 100 ml.
of ether to give a crystalline solid. After cooling
overnight, the solid is filtered, washed with cold
ether and dried in a desiccator. This material
(35.7 g.) is pulverized and suspended in 100 ml. of
ether, cooled and filtered to give 33.8 g. (98%)
of N-acetyl-trans-4-hydroxy-L-proline, 128-131 .
Recrystallization of 0.5 g. of this material from
5 ml. of acetonitrile gives 0.45 g. of colorless
20 solid, m.p. 130-132 ; [a]D -92 (c, 1~ in EtOH).
h) N-Acetyl-trans-4-methoxy-L-proline, methyl ester
A mixture of 30.0 g. (0.17 mole) of N-acetyl-
trans-4-hydroxy-L-proline and 130 g. of silver
oxide is pulverized in a mortar and this intimate
25 mixture is added to a l-liter flask with 300 ml.
of acetone. The slurry is stirred, treated
portionwise with 130 ml. of methyl iodide and the
temperature maintained below 40 by cooling with
a cold water bath. After stirring for 7 hours, the mixture is
30 allo~ed t~ stand overnight. The solid is filtered, washed well with
acetone and the filtrate concentrated on a rotary evaporator to give
3~
~69a
-17-
38.3 g. of syrupy residue. The latter is redissolved
in 350 ml. of acetone and again treated with 130 g.
of silver oxide and 130 ml. of methyl iodide to
give 41 g. of residue. The latter is distilled to
yield 32.2 g. of distillate; b.p. 130-140 (0.3 mm).
After digestion in 30 ml. of cyclohexane and cooling,
the nearly colorless solid N-acetyl-trans-4-methoxy-
L-proline methyl ester weighs 31.4 g., m.p. 71-75 .
Recrystallization from 31 ml. of ethyl acetate gives
25.1 g. (66%) of colorless solid, m.p. 76-77 .
[a] D -83 (c, 1% in EtOH).
c) trans-4-Methoxy-L-proline
To a stirred solution of 27.0 g. (0.085 mole)
of barium hydroxide ~ 8H2O in 525 ml. of water
(approx. 3.3 N) is added 11.0 g. (0.05 mole) of
N-acetyl-trans-4-methoxy-L-proline methyl ester.
The resulting solution is stirred at 18-20 for
3 hours, cooled and treated with dilute sulfuric
acid (8.8 g. of conc. H2SO4 in 20 ml. of water).
The acidic suspension is allowed to stand overnight.
The mixture is filtered through a thick layer of
Celite to give a "milky" filtrate. The latter is
concentrated on a rotary evaporator at 50 using a
high vacuum pump to give a milky residue weighing
121 g. This material is treated with dilute sulfuric
acid (19.0 g. of conc. H2SO4 in 75 ml. of water) and
the resulting mixture is stirred and refluxed for
3 hours. After cooling to 30 , the mixture is
treated portionwise with 48 g. of barium hydroxide-
8H2O and the pH then adjusted from 6.0 to 4.0 with --
dilute sulfuric acid. After standing overnight, the
mixture is filtered through a thick layer of Celite.
The "milky" filtrate is concentrated as above to
* Trade Mark
3~
I~A169a
-18-
give 50 g. of colorless dry residue. The latter is
digested with 200 ml. of hot chloroform and filtered
through a bed of Celite to remove the barium sul~ate.
The slightly turbid filtrate is concentrated on a
rotary evaporator to give a gelatinous material (17.7g.),
suspended in 100 ml. of ether, and filtered to give
7.5 g. (94%) of nearly colorless solid, m.p. 185-190
(dec.). This material is suspended in 30 ml. of
warm acetonitrile, cooled and filtered to give 4.0 g.
(50%3 of a colorless solid, trans-4-methoxy-L-proline,
m.p. 209-211 (dec.); [a]25 _75 (c, 1% in EtOH).
d) l-(3-Acetylthio-l-oxopropyl)-trans-~-methoxy-
L-proline
A solution of 3.5 g. (0.024 mole) of trans-
4-methoxy-L-proline in 50 ml. of water is stirred,
cooled to 5 and 3 g. of sodium carbonate are added.
This mixture is treated with a solution of 4.0 g.
(0.024 mole) of 3-acetylthiopropionyl chloride in
5 ml. of ether during the course of 10 minutes with
20 the intermittent addition o 3 g. of sodium carbonate
to maintain the pH at about 8Ø The mixture is
stirred in the ice-bath for an additional hour, 25 ml.
of water are added and then a solution of 5 ml. of
concentrated hydrochloric acid in 25 ml. of water
(C2 evolution). The strongly acid solution is
saturated with sodium chloride and extracted with
50 ml. of ethyl acetate (four times). The organic
phases are combined, dried (MgSO4), filtered and the
solvent evaporated to give 6.0 g. (90%) of
30 colorless syrupy 1-(3-acetylthio-1-oxopropyl)-
* Trade Mark
~ llAl69a
--19--
trans-4-methoxy-L-proline. l'his acid is dissolved
in 25 ml. of ethyl acetate and treated witl~ 4.7 g.
of dicyclohexylamine to give a solution which
rapidly becomes a solid mass. An additional 15 ml.
of ethyl acetate are added and the mixture is digested
on a steam bath, cooled and filtered to give 8.7 g.
of the dicyclohexylamine salt, m.p. 170-172 .
After crystallization from 60 ml. of acetonitrile the
colorless solid weighs 8.3 g. (75%3 m.p. 171-173;
[~]25 -35 tc, 1~ in EtOH).
The dicyclohexylamine salt is converted to
1-(3-acetylthio-1-oxopropyi)trans-4-methoxy-L-proline
by suspending 8.0 g. in 60 ml. of ethyl acetate cooled
in an ice bath and treating portionwise with 60 ml. of
10% potassium bisulfate. The clear layers are separa-
ted and the aqueous portion extracted with 60 ml.
of ethyl acetate (2X). The organic phases are
combined, dried (MgSO4), filtered and the solvent
is evaporated to give 4.6 g. (80%) of a colorless
syrup.
Example 2
1-(3-Mercapto-l-oxopropyl)-trans-4-methoxy-1,-proline
To the 1-(3-acetylthio-1-oxopropyl)-trans-4-
methoxy-L-proline obtained in Example 1 (4.6 g.,
0.017 mole) is added a cold solution of 9 ml. of
concentrated ammonia in 22 ml. of water. The base
dissolves in about 30 minutes and the resulting
solution (under ~rgon) is allowed to stand for
2 hours at room temperature. This solution is cooled,
extracted with 25 ml. of ethyl acetate (2X) and the
ethyl acetate extract is discarded. The solution
is again layered with 25 ml. of ethyl acetate and
33~:)
11~169a
-20-
acidific(l with 17 ml. of 1:1 llydrocllloric acid.
~ e mix~urc is shakcn, separa~e(l ~n(l tlle aqueous
phase extracted with 25 ml. of cthy] aco~atc(3X). 'l'hc
organic ph~ses are combined, dried (MgSO4), filtered
and the solvent removed on the rotary evaporator to
give 2.3 g. (59~) of colorless syrup, 1-(3-mercapto-
l-oxopropyl)-trans-4-methoxy-L-proline, [a]D -60
(c, 1~ in EtOH); Rf 0.49 (MeOH on silica gel, visual-
ized with nitroprusside reagent).
Anal. Calc'd. for 9H15NO4S . 1/4H2O: C, 45.46;
H, 6.57; N, 5.87; S, 13.48.
Found: C, 45.42; H, 6.78; N, 5.96; S, 13~27.
An additional 1.1 g. of product (total 3.4 g.,
87~) is obtained by saturating the aqueous phase
with sodium chloride and extracting with 25 ml.
of ethyl acetate [2X).
The sodium salt is formed by treating the syrup
with aqueous sodium bicarbonate and freeze drying.
Example 3
(trans)-1-[D-3-(Acetylthio)-2-methyl-1-oxopropyl]-
4-methoxy-L-proline
A solution of 4.3 g. (0.029 mole) of trans-
4-methoxy-L-proline in 50 ml. of water is stirred,
cooled to 5 and 3 g. of sodium carbonate are added.
This solution is treated with 5.2 g. (0.029 mole)
of D-3-(acetylthio)-2-methylpropionyl chloride in
5 ml. of ether during the course of 10 minutes
with the intermittent addition of 3 g. of sodium
carbonate to maintain the pH at about 8Ø This
mixture is stirred in the ice-bath for 1.5 hours,
25 ml. of water are added and then a solution of
6 ml. of concentrated hydrochloric acid in 25 ml.
of water (CO2 evolution). The resulting strongly
acidic solution is extracted with 50 ml. of ethyl
330
IIA169a
-21-
acetate (four times). The organic phases are
combined, dried (MgSO~), filtered and the solvent
evaporated to give 6.1 g. (73%) of (trans)-l-
[D-3-(acetylthio)-2-methyl-l-oxopropyll-4-meth
L-proline as a pale yellow syrupy residue. This
acid is dissolved in 50 ml. of ethyl acetate and
treated with a solution of 4.0 g. of dicyclohexyl-
amine in 20 ml. of ethyl acetate. The product begins
to crystallize from the solution in about a minute.
After cooling overnight the nearly colorless solid
is filtered and dried, yield 6.7 g., m.p. 175-177 ;
[]D ~55 (c, 1% in EtOH). Following crystalliza-
tion from 60 ml. of acetonitrile the nearly
colorless solid dicyclohex~lamine salt weighs 5.6 g.
(41%), m.p. 179-181, [aJD -62 (c, 1% in EtOH).
The dicyclohexylamine salt is converted to the
acid by suspending 5.5 g. in 50 ml. of ethyl acetate,
cooling in an ice-bath and treating with 50 ml. of
10% potassium bisulfate. The layers are separated
and the aqueous portion is extracted with 50 ml. of
ethyl acetate (2X). The organic phases are combined,
dried (MgSO4), filtered and the solvent evaporated to
give 3.4 g. (41%) of nearly colorless (trans)-1-[D-3-
(acetylthio)-2-methyl-1-oxopropyl]-4-methoxy-L-proline
as a syrup.
Example 4
(trans)-4-Methoxy-l-(D-3-mercapto-2-methyl-1-
oxopropyl)-L-proline
To (trans)-l-[D-3-(acetylthio)-2-methyl-1-
oxopropyl]-4-methoxy-L-proline (3.4 g.) is added a cold
solution of 8 ml. of concentrated ammonia in 20 ml.
of water. The base dissolves in about 10 minutes
3~
~IA169a
-22-
and the resulting solution (under ~rgon) is allowed
to stand at room temperature for two hours. This
solution is cooled, extracted with 20 ml. of ethyl
acetate (2X), layered with 20 ml. of ethyl acetate
S and acidified with 15 ml of 1:1 hydrochloric acid.
This mixture is saturated with sodium chloride, the
layers are separated and the aqueous phase is extracted
with 20 ml. of ethyl acetate (3X). The organic phases
are combined, dried (MgSO4), filtered and the solvent
evaporated to give 2.9 g. (100%) of nearly colorless
(trans)-4-methoxy-1-(D-3-mercapto-2-methyl-1-oxo-
propyl)-L-proline, [a]D -80 (c, 1% in EtOH);
Rf 0.53 (MeOH on silica gel, visualized with nitro-
prusside reagent).
Anal. calc'd- for CloH17NO4S 1/4H2O: C, 47-69;
Il, 6.83; N, 5.56; S, 12.73
Found: C, 47.90; H, 6.~4; N, 5.85; S, 12.76.
Example 5
(trans)-l-[D-3-(Acetylthio)-2-methyl-1-oxopropyl]-
4-ethoxy-L-proline
Utilizing the procedure described in Example 3
but substituting an equivalent quantity of trans-4-
ethoxy-L-proline (J. Med. Chem., 10, 1161 (1967), for
(trans)-4-methoxy-L-proline, (trans)-l-[D-3-(acetyl-
thio)-2~methYl-l-Oxopropyl]-4-ethoxy-L-proline is
obtained. The product is purified as the dicyclo-
hexylamine salt, m.p. 170-172 (crystallized from iso-
propyl alcohol); [a]D -64 (c, 1% in EtOH).
This salt (7.75 g.) is converted to the free
acid by treating with potassium bisulfate solution
as described in Example 4 to give 4.85 g. of nearly
colorless (trans)-l-[D-3-(acetylthio)-2-methyl-1-
oxopropyl]-4-ethoxy-L-proline as a syrup.
4~3~
~ 169a
-23-
Example 6
(trans)-4-Ethoxy-l-(D-3-mercapto-2-methyl-1-oxopropyl)-
L-proline
To the material from Example 5 (4.85 g.) is
5 added a cold solution of 9 ml. of concentrated ammonia
in 22 ml. of water (under Argon). The mixture is treat-
ed in the same manner as Example 4 to give 4.2 g.
(100%) of nearly colorless (trans)-4-ethoxy-1-(D-3-
mercapto-2-methyl-l~oxopropyl)-L- proline as a syrup,
[a]D -80 (c, 1% in EtOH); Rf 0.64 (MeOH on silica
gel, visualized with nitroprusside reagent).
Anal. calc d. for Cll 19 4
N, 5.36; S, 12.27
Found: C, 50.34; H, 7.34; N, 5.39; S, 12.11.
Example 7
(cis)-l-[D-3-(Acetylthio)-2-methyl-1-oxopropyl]-4-
methoxy-L-proline
a) N-Carbobenzyloxy-cis-4-hydroxy-L-proline
N-Carbobenzyloxy-4-keto-L-proline (10 g.,
20 0.038) is dissolved in 300 ml. of methanol and reduced
with 5.8 g. (0.15 mole) of sodium borohydride in
20 ml. of water as described in JACS, 79, 189 (1957) to
give 8.7 g. of a foamy product. This material is
dissolved in 30 ml. of ethanol, treated with 3.5 g.
25 f cyclohexylamine in some ethanol, and diluted to
500 ml. with ether. On seeding and rubbing, the
crystalline cyclohexylamine salt separates rapidly to
give 10.8 g.; m.p. 163-165. This cyclohexylamine
salt is then treated with 30 ml. of 2N HCl and
30 extracted with ethyl acetate (4 x 50 ml.) to yield as
~4~3~ ~lAl69a
-24-
a glass-like material 8 g. of N-carbobenzyloxy-cis-
4-hydroxy-L-proline.
b) N-Carbobenzyloxy-cis-4-methoxy-L-proline, methyl
ester
N-Carbobenzyloxy-cis-4-hydroxy-L-proline
(13.9 g., 0.052 mole) is treated with 40 g. of silver
oxide and 40 ml. of methyl iodide (2x) in acetone
(100 ml. initially, then 120 ml.) as described in
Example l(b) to yield 17.5 g. (100%) of N-carbobenzyl-
oxy-cis-4-methoxy-L-proline, methyl ester as a yellow
oil.
c) N-Carbobenzyloxy-cis-4-methoxy-L-proline
The N-carbobenzyloxy-cis-4-methoxy-L-proline,
methyl ester (17.5 g., approximately 0.052 mole) is
dissolved in 135 ml. of methanol, treated dropwise at
-1 to 4 with 32 ml. (0.064 mole) of 2N sodium
hydroxide, then kept at 0 for one hour, and at room
temperature overnight. After removing about half of
the solvent on a rotary evaporator, the solution is
diluted with 300 ml of water, washed with ether (wash
discarded), acidified while cooling with 12.5 ml. of
1:1 hydrochloric acid to pH 2, and extracted with
ethyl acetate (4 x 150 ml.). The extracts are combined,
dried (MgSO4), filtered and the solvent evaporated to
give 15 g. of an orange-yellow syrup. The latter is
dissolved in 60 ml. of ethanol, treated with 6 g. of
cyclohexylamine in 10 ml. of ethanol and diluted to
900 ml. with ether. On seeding and rubbing, crystalline
N-carbobenzyloxy-cis-4-methoxy-L-proline, cyclohexyl-
amine salt separates: weight after cooling overnight
IIA169a
-25-
10.2 g., m.p. 148-150 (s. 144 ), [a]D -35
(c, 1~ in ethanol). Following recrystallization
from 40 ml. of acetonitrile, the nearly colorless
solid weighs 8.8 g., m.p. 150-152 (s. 145 ),
[a]D ~34 (c, 1% in ethanol).
The cyclohexylamine salt is treated with
hydrochloric acid to yield 6.9 g. (48%) of N-carbo-
benzyloxy-cis-4-methoxy-L-proline as a pale yellow
viscous syrup, [a]D -32 (c, 1% in ethanol).
d) cis-4-Methoxy-L-proline
A mixture of 6.8 g. of N-carbobenzyloxy-cis-4-
methoxy-L-proline, 210 ml. of 2:1 methanol and water,
and 2.3 g. of 5% Pd-C is placed on a hydrogenator at
3 atmospheres of hydrogen for four hours. The mixture
is filtered to remove the catalyst and the filtrate
evaporated to give 3.15 g. of a grayish solid; m.p.
218-220 (dec.). A sample is crystallized from
methanol-ether to yield colorless cis-4-methoxy-L-
proline, m.p. 224-226 (dec.), [a]D5 -42 (c, 1% in
20 methanol).
Anal- Calc'd- for C6HllN3 C~ 49-64; H~ 7~64; N~ 9-65
Found: C, 49.63; H, 7.71; N, 9.54.
e) (cis)-l-[D-3-(Acetylthio)-2-methYl-l-oxopropyl]-
4-methoxy-L-proline
2S cis-4-Methoxy-L-proline (3 g., 0.021 mole) and
4.2 g. (0.023 mole) of D-3-acetylthio-2-methylpropionyl
chloride in 5 ml. of ether are reacted in 60 ml. of
water in the presence of sodium bicarbonate as
described in Example 3. Approximately 20 ml. of
30 25% sodium carbonate (w/v) is required to bring the
4~3~0
HA169a
-26-
pH initially to 8.5 and to maintain it at 7.5 to 8.4
during the acylation. The resulting crude viscous
product (6.4 g. ) is dissolved in 50 ml. of ethyl
acetate and -treated with 3.9 g. of dicyclohexylamine
in 20 ml. of ethyl acetate. The product crystallizes
from the solution and is filtered and dried to yield
6.6 g. of dicyclohexylamine salt, m.p. 172-174
(s. 170 ), [a]D -60 (c, 1% in ethanol). 6.5 g. of
this material is recrystallized from 35 ml. of
acetonitrile to yield 6 g. of colorless solid dicyclo-
hexylamine salt; m.p. 173-175 (s. 170 ), [a]D -60
(c, 1~ in ethanol).
Anal. Calc'd.for C12HlgNO5S C12 23
N,5.95; S, 6.81
15 Found: C, 61,16; H, 8.81; N, 5.95; S, 6.67.
Utilizing the procedure of Example 3, the
dicyclohexylamine salt is converted to the acid by
suspending 5.9 g. in 60 ml. of ethyl acetate, cooling
in an ice-bath and treating wi~h 60 ml. of 10% potassium
20 bisulfate. The layers are separated and the aqueous
phase is extracted with 50 ml. of ethyl acetate (4x).
The organic phases are combined, dried (MgSO4),
filtered and the solvent evaporated to give 3.5 g.
(60%) of colorless (cis)-1-[D-3-(acetylthio)-2-
25 methyl-1-oxopropyl]-4-methoxy-L-proline; m.p. 90-92
(triturated with ether), [a]D6 -139 (c, 1% in ethanol),
Rf 0.63 (methanol on silica gel).
Anal- Calc'd- for C12HlgNO5S C, 49-81; H~ 6-62;
N, 4.840 Found: C, 49.85; H, 6.66; N, 4.97.
169a
-27-
Example 8
(cis)-4-Methoxy-l-(D-3-mercapto-2-methyl-1-oxopropyl)-
L-proline
The (cis)-l-[D-3-(acetylthio)-2-methyl-1-oxopro-
pyl]-4-methoxy-L-proline (2.9 g., 0.01 mole) is
hydrolyzed in 15 ml. water containing 6.5 ml. of
concentrated ammonia as described in Example 4 to
give 2.3 g. (93%) of extremely viscous (cis)-4-
methoxy-l-(D-3-mercapto-2-methyl-1-oxopropyl)-L-
10 proline which becomes waxy on standing; [a~D -88
(c, 1% in e-thanol).
Example 8a
(cis)-4-Methoxy-l-(D-3-mercapto-2-methyl-1-oxopropyl)-L-
proline, l-adamantanamine salt
A solution of 0.55 g. (0.0022 mole) of cis-4-
methoxy-l-(D-3-mercapto-2-methyl-1-oxopropyl)-L-proline
in 15 ml. of ethyl acetate is treated under an atmos-
phere of argon with a warm solution of 0.34 g.
(0.0022 mole) of l-adamantaneamine in 10 ml. of
20 ethyl acetate to precipitate the salt. After three
hours in the cold, the colorless solid is filtered
under argon ~solvent held tenaciously), washed with
some cold ethyl acetate, and dried in vacuo for
twenty hours to yield 0.7 g. (79~) of (cis)-4-
25 methoxy-1-(D-3-mercapto-2-methyl-1-oxopropyl)-L-proline,
l-adamantanamine salt, m.p. 215-217 (s. 210, dec.
220 ), [a]D -60 (c, 1~ in methanol).
{33~3
HA169a
-28-
Example 9
(cis)-4-Methoxy-1-(3-mercapto-2-methyl-1-oxopropyl)-
L-proline
a) (cis)-4-Methoxy-1-[3-(benzoylthio)-2-methyl-
l-oxopropyl]-L-proline
Interaction o 3-benzoylthio-2-methylpro-
pionyl acid chloride (prepared by treating 3-benzoyl-
thio-2-methylpropanoic acid with thionyl chloride)
with cis-4-methoxy-L-proline according to the general
procedure of Example 3 yields (cis)-4-methoxy-1-
[3-(benzoylthio)-2-methyl-1-oxopropyl]-L-proline.
b) (cis)-4-Methoxy-1-(3-mercapto-2-methyl-1-
oxopropyl)-L-proline
Hydrolysis of (cis)-2-methoxy-1-[3-(benzoylthio)-
2-methyl-1-oxopropyl]-2-proline with an aqueous
ammonia solution according to the general procedure
of Example 4 yields (cis)-4-methoxy-1-(3-mercapto-
2-methyl-1-oxopropyl)-L-proline.
1~4~
11~169
-29-
Example 10
(trans)-l-[D-3-(Acetylthio)-2-methyl-1-oxopropyl]-4-
propoxx-L-proline
a) N-acetyl-trans-4-propoxy-L-proline, propyl ester
Interaction of 30 g. of N-acetyl-trans-4-
hydroxy-L-proline from Example l(a) with 110 g. of
silver oxide and 110 ml. of propyl iodide in 300 ml.
of acetone according to the procedure of Example l(b)
gives 19.6 g. (41~) of pale yellow-orange N-acetyl-
10 trans-4-propoxy-L-proline, propyl ester; b.p.
155-165 (0.2 mm.).
b) N-Acetyl-trans-4-propoxy-L-proline
A solution of 6 g. (0.15 mole) of sodium
hydroxide in 150 ml. of water is added to 19.4 g.
(0.075 mole) of N-acetyl-trans-4-propoxy-L-proline,
propyl ester to give a pale orange solution. After
standing overnight at room temperature, the solution
is extracted with 60 ml. of ethyl acetate (wash
discarded), then acidified with 1:1 hydrochloric
20 acid, then saturated with sodium chloride and
extracted with 50 ml. of chloroform (3x). The
organic phases are combined, dried (MgSO4),
filtered and the solvent evaporated to give 12.6 g.
of a brown oil. The latter is dissolved in 80 ml.
25 of ethyl acetate and treated with a solution of
10.7 g. of dicyclohexylamine in 20 ml. of ethyl
acetate. The salt crystallizes at room temperature.
After standing overnight under refrigeration, the
dicyclohexylamine salt is filtered and washed with
30 cold ethyl acetate to give 17.3 g. of nearly colorless
3(~
~IA169a
-30-
solid dicyclohexylamine salt; m.p. 148-153. Recrystal-
lization of this material from 125 ml. of ethyl acetate
gives 14.5 g. of colorless dicyclohexylamine salt;
m.p. 157-159 , [a]D -30 (c, 1% in ethanol).
5 Anal. Cald'd. for ClOH17NO4 C12H23N C~ 66-63;
H, 10.17;,N, 7.07
Found: C, 66.47; H, 10.22; N, 7.06.
The dicyclohexylamine salt (14.4 g.) is con-
verted to the free acid by pulverizing, suspending in
lO 100 ml. of ethyl acetate and treating the slurry
portionwise with 100 ml. of 10% potassium bisulfate.
The organic phase is separated and the aqueous phase
is extracted with 100 ml. of ethyl acetate (2x). The
organic phases are combined, dried (MgSO4), filtered,
15 and the solvent evaporated to give 6.7 g. (41~)
of N-acetyl-trans-4-propoxy-L-proline as a pale
brown liquid.
c) (trans)-l-[D-3-(Acetylthio)-2-methyl-1-oxopropyl]-
4-propoxy-L-proline
N-Pcetyl-trans-4-propoxy-L-proline (6.4 g.,
0.03 mole) is treated with a solution of 10 g. of
concentrated sulfuric acid in 100 ml. of water and
the resulting solution is stirred and refluxed for
three hours. The solution is then cooled to 15,
25 treated portionwise with 12 g. of sodium carbonate
to bring the pH to 8.0, and then treated with a
solution of 5.4 g. (0.03 mole) of D-3-acetylthio-2-
methylpropionyl chloride in 5 ml. of ether during
10 minutes while 7 g. of so'~ium carbonate are added
30 to maintain the pH at about 8Ø The mixture is then
33~
~l~169a
stirred in the ice-bath for 30 minutes and at room
temperature for one hour. The product is then
isolated and purified as a dicyclohexylamine salt
according to the procedure of Example 3 to yield 6.3 g.
of dicyclohexylamine salt; m.p. 165-167 (from aceto-
nitrile), [a]25 -56 (c, 1% in ethanol).
Anal. Calc'd. for C14H23NO5S C12 23
H, 9.30; N, 5.61; S, 6.43
Found: C, 62.35; H, 9.48; N, 5.88; S, 6.45.
The dicyclohexylamine salt (6.1 g.) is converted
to the free acid by suspending in 60 ml. of ethyl
acetate, cooling in an ice-bath and treating with 60 ml.
of 10% potassium bisulfate. The layers are separated
and the aqueous phase is extracted with 60 ml. of
15 ethyl acetate (2x). The organic phases are combined,
dried (MgSO4), filtered and the solvent evaporated to
give 4.0 g. (42%) of (trans)-1-[D-3-(acetylthio)-2-
methyl-l-oxopropyl]-4-propoxy-L-proline as a nearly
colorless syrup.
Example 11
1-(D-3-Mercapto-2-methyl-l-oxopropYl)-trans-4-pr
L-proline
Hydrolysis of 4.0 g. of (trans)-1-[D-3-(acetyl-
thio)-2-methyl-1-oxopropyl]-4-propoxy-L-proline with
25 8 ml. of concentrated ammonia in 20 ml. of water under
argon according to the procedure of Example 4 gives
3.42 g. (97%) of 1-(D-3-mercapto-2-methyl-1-oxopropyl)-
trans-4-propoxy-L-proline as a nearly colorless
syrup, [a]D -72 (c, 1% in ethanol).
~f~4~
HA169a
-32-
Anal. Calc~- for CL2ll2NO~S 1/4 ll2O C, 51-49;
Il, 7.74; N, 5.05; S, 11.46
Found: C, 51.66; H, 7.76; N, 5.94; S, 10.51.
Example 12
3-Mercapto-l-oxopropyl)-cis-4-methoxy-L-proline
a) 1-(3-Acetylthio-1-oxopropyl)-cis-4-methoxy-L-
proline
Following the procedure of Example 1 (d), cis-4-
methoxy-L-proline is treated with a solution of
3-acetylthiopropyl chloride in the presence of
sodium carbonate to yield l-(3-acetylthio-1-
oxopropyl)-cis-4-methoxy-L-proline.
b) l-(3-Mercapto-l-oxopropyl)-cis-4-methoxy-L-proline
The 1-(3-acetylthio-1-oxopropyl)-cis-4-methoxy-
L--proline is hydrolyzed with an aqueous solution of
ammonia according to the procedure of Example 2 to
yield l-(3-mercapto-1-oxopropyl)-cis-4-methoxy-L-
proline.
Example 13
(cis)-4-Ethoxy-l-(D-3-mercapto-2-methyl-1-oxopropyl)-L-
proline
a) cis-4-Ethoxy-L-proline
Following the procedure of Example 7, parts (a)
to (d) but substituting ethyl iodide for the methyl
iodide in part (b), one obtains (cis)-4-ethoxy-L-
proline.
b) (cis)-1-[D-3-(Acetylthio?-2-methyl-1-oxGpropyl]-
4-ethoxy-L-proline
The (cis)-4-ethoxy-L-proline is reacted with a
solution of D-3-acetylthio-2-methylpropionyl chloride
3~3
HA169a
in the prcsence of sodium carbonatc according to the
procedure o~ ~xample 7(e) to yiold (cis)-1-[D-3-
(acetylthio)-2-methyl-1-oxopropyl]-4-ethoxy-L-proline.
c) (cis)-4-Ethoxy-l-(D-3-mercapto-2-methyl-1-oxopro-
yl)-L-proline
The cis-l-[D-3-(acetylthio)-2-methyl-1-
oxopropyl]-4-ethoxy-L-proline is hydrolyzed with
a solution of aqueous ammonia. according to the
procedure of Example 8 to yield (cis)-4-ethoxy-1-
0 (D-3-mercapto-2-methyl-1-oxopropyl)-L-proline.
Example 14
(trans)-4-Allyloxy-l-(D-3-mercapto-2-methyl-1-oxopropyl)-
L-proline
a) (trans)-4-Allyloxy-L-proline
Using the procedure of Example 1, part b, but
substituting allyl bromide for methyl iodi.de gives the
(trans)-N-acetyl-4-allyl-L-proline, allyl ester.
The latter is then hydrolyzed as described in
Example 1, part c, to give (trans)-4-allyloxy-L-
proline.
b) (trans)-l-[D-3-(Acetylthio)-2-methyl-1-oxopropyl]-
4-allyloxy-L-proline
Interaction of the (trans)-4-allyloxy-L-proline
from part(a) with an equivalent quantity of D-3-
(acetylthio)-2-methylpropionyl chloride according to
the procedure of Example 3 gives (trans)-1-[D-3-
(acetylthio)-2-methyl-1-oxopropyl]-4-allyloxy-L-
proline.
c) (trans)-4-Allyloxy-l-(D-3-mercapto-2=methyl-1-
oxopropyl)-L-proline
The (trans)-1-[D-3-(acetylthio)-2-methyl-1-
~ 3~ HAl69a
-34-
oxopropyl]-4-allyloxy-L-proline is hydrolyzed with an
aqueous ammonia solution according to the procedure
of Example 4 to give (trans)-4-allyloxy-1-
(D-3-mercapto-2-methyl-1-oxopropyl)-L-proline.
Example 15
l-(D-3-Mercapto-2-methyl-1-oxopropyl)-trans-4-
propargyloxy-L-proline
a) (trans)-4-propargyloxy-L-prol_ne
Using the procedure of Example 1, part b, but
substituting propargyl bromide for methyl iodide
gives the (trans)-N-acetyl-4-propargyl-L-proline,
propargyl ester. The latter is then hydrolyzed as
described in Example 1, part c, to give the
(trans3-4-propargyloxy-L-proline.
b) (trans)-1-[D-3-(Acetylthio)-2-methyl-1-oxo-
propyl]-4-propargyloxy-L-proline
Interaction of the (trans)-4-propargyloxy-L-
proline from part ~) with an equivalent quantity of
D-3-(acetylthio)-2-methylpropionyl chloride according
to the procedure of Example 3 gives (trans)-l-
[D-3-(acetylthio)-2-methyl-1-oxopropyl]-4-propargyl-
oxy-L-proline~
c) l-(D-3-Mercapto-2-methyl-1-oxopropyl)-trans-4-
propargyloxy-L-proline
The (trans)-l-[D-3-(acetylthio)-2-methyl-
l-oxopropyl]-4-propargyl-L-proline is hydrolyzed with
an aqueous ammonia solution according to the pro-
cedure of Example 4 to give l1(D-3-mercapto-2-
methyl-l-oxopropyl)]-trans-4-propargyloxy-L-proline.
~ 3~ HA169a
-35-
Example 16
(trans)-4-Benzyloxy-l-(D-3-mercapto-2-methyl-1-
. _ _
oxopropyl)-L-proline
a) (trans)-4-Benzyloxy-L-proline
.
Using the procedure of Example 1, part b,
but substituting benzyl chloride for methyl iodide
gives the (trans)-N-acetyl-4-benzyloxy-L-proline,
benzyl ester. The latter is then hydrolyzed as
described in Example 1, part c, to give the (trans)-
4-benzyloxy-L-proline.
b) (trans)-l-[D-3-(Acetylthio)-2-methyl-1-oxopropyl]-
4-benzyloxy-L-proline
Interaction of the (trans)-4-benzyloxy-L-
proline from par~(a) with an equivalent quantity of
D-3-(acetylthio)-2-methylpropionyl chloride according
to the procedure of Example 3 gives (trans)-1-[D-3-
(acetylthio)-2-methyl-1-oxopropyl]-4-benzyloxy-L-
proline.
c) (trans)-4-Benæyloxy-l-(D-3-mercapto-2-methyl-1-
oxopropy~ L-proline
The (trans)-l-[D-3-(acetylthio)-2-methyl-
l-oxopropyl]-4-benzyloxyl-L-proline is hydrolyzed
with an aqueous ammonia solution according to the
procedure of Example 4 to give (trans)-4-benzyloxy 1-
(D-3-mercapto-2-methyl-1-oxopropyl)-L-proline.
Example 17
1-(D-3-r~lercapto-2-methyl-1-oxopropyl)-trarls-4-
phenethyloxy-L-proline
a) (trans)-4-Phenethyloxy-L-proline
Using the method of Example 1, part b, but
33V
~IA169a
-36-
substituting phenethyl bromide for methyl iodide
yives the (trans)-N-acetyl-4-phenethyloxy-L-proline,
phenethyl ester. The latter is then hydrolyzed as
described in Example 1, part c, to give the (trans)-
4-phenethyloxy-L-proline.
b) (trans)-1-[D-3-(Acetylthio) 2-methyl-1-oxopropyl]-
4-phenethyloxy-L-proline
Interaction of the (trans)-4-phenethyloxy-L-
proline from part (a)with an equivalent quantity of
D-3-(acetylthio)-2-methylpropionyl chloride according
to the procedure of Example 3 gives (trans)-1-[D-3-
(acetylthio)-2-methyl-1-oxopropyl]-4-phenethyloxy-
L-proline.
c) l-(D-3-Mercapto-2-methyl-1-oxopropyl)-trans-4-
phenethyloxy-L-proline
The trans-l-[D-(acetylthio)-2-methyl-1-
oxopropyl]-4-phenethyloxy-L-proline is hydrolyzed
with an aqueous ammonia solution according to the
procedure of Example 4 to give 1-(D-3-mercapto-2-
methyl-1-oxopropyl)-trans-4-phenethyloxy-L-proline.
Example 18
l-(D-3-Mercapto-2-methyl-1-oxopropyl)-cis-3-methoxy-L-
proline
a) l-[D-3-(Acetylthio)-2-methyl-1-oxopropyl]-cis-
3-methoxy-L-proline
Utilizing the procedure described in Example 7,
but substituting an equivalent quantity of (cis)-3-
methoxy-L-proline (J. Amer. Chem. Soc. 85, 3863
(1963)) for the (cis)-4-methoxy-L-proline, l-[D-3-
(acetylthio)-2-methyl-1-oxopropyl]-cis-3-methoxy-L-
335~
I~Al69a
-37-
proline is obtained.
b) l-(D-3-Mercapto-2-methyl-l-oxopropyl)-cis-3-
ethoxy-L-proline
The l-[D-3-(acetylthio)-2-methyl-1-oxopropyl]-
cis-3-methoxy-L-proline is hydrolyzed with an aqueous
ammonia solution according to the procedure of Example
4 to yield l-(D-3-mercapto-2-methyl-l-oxopropyl)-cis-3-
methoxy-L-proline.
Example l9
l-(D,L-3-Mercapto-2-methyl-l-oxopropyl)-trans-3-methoxy-
L-proline
a? l-[D,L-3-(Acetylthio)-2-methyl-1-oxopropyl]-trans-
3-methoxy-L-proline
Interaction of equivalent quantities of (trans)-
3-methoxy-L-proline (J. Amer. Chem. Soc. 85, 3863
(1963)) and D,L-3-(acetylthio)-2-methylpropionyl
chloride according to the procedure described in
Example 3 gives l-[D,L-3-(acetylthio)-2-methyl-l-
oxopropyl]-trans-3-methoxy-L-proline.
b) l-(D,L-3-Mercapto-2-methyl-l-oxopropyl)-trans-3-
methoxy-L-proline
The l-[D,L-3-(acetylthio)-2-methyl-l-oxopropyl]-
trans-3-methoxy-L-proline is hydrolyzed with an
aqueous ammonia solution according to the procedure of
Example 4 to yield l-(D,L-3-mercapto-2-methyl-l-
oxopropyl)-trans-3-methoxy-L-proline.
Example 20
l-(D-3-Mercapto-2-methyl-1-oxopropyl)-cis-4-methylthio-
L-proline
HA169a
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a) 1-[D-3-(~cetylthio)-2-metllyl-1-oxor~ropyl]-cis-4-
methylthio-L-proline
Interaction of equivalent quantities of cis-
4-methylthio-L-proline [J. Amer. Chem. Soc., 79,
185 (1957)] and D-3-(acetylthio)-2-methylpropionyl
chloride according to the procedure of Example 3 gives
1-[D-31acetylthio)-2-methyl-1-oxopropyl]-cis-4-
methylthio-L-proline.
b) l-(D-3-Mercapto-2-methyl-1-oxopropyl)-cis-4-
methylthio-L-proline
The l-[D-3-( acetylthio)-2-methyl-1-oxopropyl]-
cis-4-methylthio-L-proline is hydrolyzed with an
aqueous ammonium solution according to the procedure
of Example 4 to give 1-(D-3-mercapto-2-methyl-1-
oxopropyl)-cis-4-methylthio-L-proline.
Example 21
l-(D-3-Mercapto-2-methyl-1-oxopropyl)-trans-4-
methylthio-L-proline
a) l-[D-3-(Acetylthio)-2-methyl-1-oxopropyl]-trans-
4-methylthio-L-proline
Interaction of equivalent quantities of trans-
4-methylthio-L-proline [J. Amer. Chem. Soc., 79,
185 (1957)] and D-3-(acetylthio)-2-methylpropionyl
chloride according to the procedure of Example 3 gives
1-[D-3-(acetylthio)~-methyl-1-oxopropyl]-trans-4-
methylthio-L-proline.
b) l-(D-3-Mercapto-2-methyl-1-_xopropyl)-trans-4-
methylthio-L-proline
The l-[D-3-(acetylthio)-2-methyl-1-oxopropyl]-
trans-4-methylthio-L-proline is hydrolyzed with an
330
HA169a
-39-
aqueous ammonia solution according to the procedure
of Example 4 to give 1-(D-3-mercapto-2-methyl-1-
oxopropyl)-trans-4-methylthio-L-proline.
xample 22
1-(D-3-Mercapto-3-methyl-1-oxopropyl)-cis-4-(4-
pentenylthio)-L-proline
a) (cis)-4-(4-Pentenylthio)-L-proline
Interaction of (cis)-N-acetyl-4-mercapto-L-
proline [Chem. Pharm. Bull., 20, 543 (1972)] with
5-bromo-1-pentene in acetone in the presence of
silver oxide according to the procedure of Example 1,
part b, gives the (cis)-N-acetyl-4-t4-pentenylthio-L-
proline, 4-pentenyl ester. The latter is then
hdyrolyzed as described in Example 1, part c, to
give the cis-4-(4-pentenylthio)-L-proline.
b) l-[D-3-(Acetylthio)-3-methyl-1-oxopropyl]-cis-
4-(4-pentenylthio)-L-proline
Interaction of cis-4-(4-pentenylthio)-L-proline
with an equivalent am~unt of D-3-(acetylthio)-3-methyl-
propionyl chloride according to the procedure of
Example 3 gives 1-[D-3-(acetylthio)-3-methyl-1-
oxopropyl]-cis-4-(4-pentenylthio)-L-proline.
c) l-(D-3-Mercapto-3-methyl-1-oxopropyl)-cis-4-
(4-pentenylthio)-L-proline
The l-[D-3-(acetylthio)-3-methyl-1-oxopropyl]-
cis-4-(4-pentenylthio)-L-proline is hydrolyzed with
an aqueous ammonia solution according to 1the procedure
of Example 4 to yield 1-(D-3-mercapto-3-methyl-1-
oxopropyl)-cis-4-(4-pentenylthio)-L-proline.
HA169a
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Example 23
_ rans)-l-[D-3-(Acetylthio)-2-methyl-1-oxopropyl3-
4-methoxy-L-proline, methyl ester
A solution of the material from Example 3 in
ether is treated with a slight excess of diazomethane.
After standing at room temperature, the solvent is
evaporated to give (trans)-l-[D-3-(acetylthio)-2-
methyl-l-oxopropyl]-4-methoxy-L-proline, methyl ester.
Similarly, by employing the cis material
from Example 7 in this procedure one obtains (cis)-
l-[D-3-(acetylthio)-2-methyl-1-oxopropyl-4-methoxy-
L-proline, methyl ester.
Example 24
1,1'-[Dithiodi-(l-D-3-mercapto-2-methyl-1-oxopropyl)3-
biS-[(trans)-4-methoxy-L-proline]
A solution of the material from Example 4 is
dissolved in ethanol, stirred and treated with a
solution of one equivalent of iodine in ethanol.
The pH of the solution is maintained at 6-7 by the
addition of N-sodium hydroxide solution. The
solvent is evaporated and the residue extracted
with ethyl acetate. After drying over MgSO4, the
solution is filtered and the solvent is removed
to give l,l'-[dithiodi(l-D-3-mercapto-2-methyl-1-
oxopropyl)]-bis-[(trans)-4-methoxy-L-proline].
Similarly, by employing the cis material
from Example 8 in this procedure one obtains 1,1'-
[dithiodi-(1-D-3-mercapto-2-methyl-1-oxopropyl)]-
bis-[(cis)-4-methoxy-L-proline].
33V
E1~169a
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Example 25
Sodium salt of (trans)-4-methoxy-1-(D-3-mercapto-
.
2-methyl-1-oxopropyl)-L-proline
A solution of 2.5 g. of material from
Example 4 in 25 ml. of water is treated with
0.84 g. of sodium bicarbonate. The solution is
freeze-dried to give the sodium salt of (trans)-4-
methoxy-l-(D-3-mercapto-2-methyl-1-oxopropyl)-L-proline.
Similarly, by employing the cis material
from Example 8 in this procedure one obtains the
sodium salt of (cis)-4-methoxy-1-(D-3-mercapto-2-
methyl-l-oxopropyl)-L-proline.
~xample 26
1-(4-Mercapto-l-oxobutyl)-cis-4-methoxy-L-proline
a) (cis)-l-(4-Acetylthio-l-oxobutyl)-4-metho_y-L-
proline
Interaction of an equivalent quantity of
(cis)-4-methoxy-L-proline with 4-acetylthiobutyroyl
chloride according to ~he procedure described in
Example 1 gives (cis)-1-(4-acetylthio-1-oxobutyl)-
4-methoxy-L-proline.
b) 1-(4 Mercapto-l-oxobutyl)-cis-4-methoxy-L-proline
Hydrolysis of (cis)-1-(4-acetylthio-1-oxobutyl)-
4-methoxy-L-proline with an aqueous ammonia solution
according to the procedure of Example 2 yields 1-(4-
mercapto-l-oxobutyl)-cis-4-methoxy-L-proline.
Example ?7
l-(L-3-Mercapto-2-eth ~-1-oxopropyl)-trans-4-methox_-
D-proline
33~3
-42-
a) (trans)-l-[L-(3-Acetylthio)-2-ethyl-1-oxopropyl]-
4-methoxy-D-proline
Utilizing the procedure of Example 1 but
substituting ttrans)-4-hydroxy-D-proline for the
(trans)-4-hydroxy-L-proline inpart (a) the (trans)-
4-methoxy-D-proline is obtained. By interacting the
latter compound with L-(3-acetylthio)-2-ethylpro-
pionyl chloride according to the procedure of Example
3, (trans)-1-[L-(3-acetylthio)-2-ethyl-1-oxopropyl]-
4-methoxy-D-proline is obtained.
b) l-(L-3-Mercapto-2-ethyl-1-oxopropyl)-trans-4-
methoxy-D-proline
Hydrolysis of (trans)-l-[L-(3-acetylthio)-2-
ethyl-l-oxopropyl]-4-methoxy-D-proline with an
aqueous ammonia solution according to the procedure
of Example 4 gives 1-(L-3-mercapto-2-ethyl-1-
oxopropyl)-trans-4-methoxy-D-proline.
Example 28
1-(2-Mercapto-l-oxoethyl)-trans-4-methoxy-L-proline
a) (trans)-1-(2-Acetylthio-l-oxoethyl?-4-methoxy-L-
proline
Utilizing the procedure of Example 1, but
substituting 2-acetylthioacetyl chloride for the
3-acetylthiopropionyl chloride, (trans)-1-(2-acetyl-
thio-1-oxoethyl)-4-methoxy-L-proline is obtained.
b) 1-(2-Mercapto-l-oxoethyl)-trans-4-methoxy-L-
proline
Hydrolysis of trans-1-(2-acetylthio-1-oxoethyl)-
4-methoxy-L-proline with an aqueous ammonia solution
according to the procedure of Example 2 yields
~ 3~ HA169a
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1-(2-mercapto-1-oxoethyl)-trans-4-metlloxy-I.-proline.
E _mple 29
1-(2-Mercapto-1-oxoethyl)-cis-4-methoxy-L-proline
a) (cis)-l-(2-Acetylthio-l-oxoethyl)-4-methoxy-L-
proline
Following the procedure of Example 28, cis-
4-methoxy-L-proline is treated with a solution of
2-acetylthioacetyl chloride in the presence of sodium
carbonate to yield (cis)-l-(2-acetylthio-1-oxoethyl)-
4-methoxy-L-proline.
b) l-(2-Mercapto-l-oxoethyl)-cis-4-methoxy-L-proline
Hydrolysis of (cis)-1-(2-acetylthio-1-oxoethyl)-
4-methoxy-L-proline with an aqueous ammonia solution
yields l-~2-mercapto-1-oxoethyl)-cis-4-methoxy-L-
proline,
Example 301-(2-Mercapto-l-oxoethyl)-cis-4-methylthio-L-proline
a) (cis)-l-(2-Acetylthio-1-oxoethyl)-4-methylthio-
L proline
Interaction of equivalent quantities of
(cis)-4-methylthio-L-proline [J. Amer. Chem. Soc.,
_, 185 (1957)] and 2-acetylthioacetyl chloride accord-
ing to the procedure described in Example 1, yields
(cis)-1-(2-acetylthio-1-oxoethyl)-4-methylthio-L-
proline,
b) l-(2-Mercapto-l-oxoethyl)-cis-4-methylthio-L-
proline
Hydrolysis of (cis)-1-(2-acetylthio-1-oxoethyl)-
4-methylthio-L-proline with an aqueous ammonia
solution according to the procedure of Example 2
~ 3~ llA169a
yields l-(2-mereapto-1-oxoethyl)-eis-4-methylthio-L-
proline.
Example 31
l-(D-3-Mercapto-3-methyl-1-oxopropyl)-cis-4-(4-
pentynylthio)-L-proline
a) (eis)-l-[D-3-(~cetylthio)-3-methyl-1-oxopropyl]-
4-(4-pentynylthio)-L-proline
Interaction of (eis)-N-acetyl-4-mercapto-L-
proline with 5-ehloro-1-pentyne in acetone in the
presence of silver oxide according to the proeedure
of Example 1, part b, gives (cis)-N-acetyl-4-(4-
pentynylthio)-L-proline, 4-pentynyl ester. The
latter is then hydrolyzed as described in Example 1,
part c, to give the (cis)-N-aeetyl-4-(4-pentynylthio)-
L-proline. Interaetion of this compound with an
equivalent quantity of D-3-(acetylthio)-3-methyl-
propionyl chloride aceording to the procedure of
Example 3 gives (cis)-1-[D-3-(aeetylthio)-3-methyl-
l-oxopropyl]-4-(4-pentynylthio)-L-proline.
b) 1-(D-3-Mereapto-3-methyl-1-oxopropyl)-eis-4-(4-
pentynylthio)-L-proline
Hydrolysis of (eis)-l-[D-3-(aeetylthio)-3-
methyl-l-oxopropyl]-4-(4-pentynylthio)-L-proline
with an aqueous ammonia solution aeeording to the
proeedure of Example 4 gives 1-(D-3-mereapto-3-methyl-
1-oxopropyl)-eis-4-(4-pentynylthio)-L-proline.
Example 32
(eis)-4-Benzylthio-1-(D,L-3-mereapto-3-ethyl-1-
oxopropyl)-L-proline
~ 3~ HA169a
-45-
]-[D,L-3-(~cetylthio)
4-benzylthio-L-proline
-
Interaction of (cis)-l~-acetyl-4-mercapto-L-
proline with benzyl chloride in acetone in the
presence of silver oxide according to the procedure
of Example 1, part b, gives (cis)-N-acetyl-4-benzyl-
thio-L-proline, benzyl ester. The latter is hydrolyzed
as described in Example 1, part c, to give (cis)-N-
acetyl-4-benzylthio-L-proline. Interaction of this
compound with an equivalent amount of D,L-3-
(acetylthio)valeroyl chloride according to the
procedure of Example 3 gives (cis)-1-[D,L-3-(acetyl-
thio)-3-ethyl-1-oxopropyl]-4-(benzylthio)-L-proline.
b) (cis)-4-Benzylthio-l-(D,L-3-mercapto-3-eth~l-1-
oxopropy-l)-L-proline
Hydrolysis of (cis)-l-[D,L-3-(acetylthio)-3-
ethyl-l-oxopropyl]-4-(benzylthio)-L-proline with an
aqueous ammonia solution according to the procedure
of Example 4 gives (cis)-4-benzylthio-1-(D,L-3-
0 mercapto-3-ethyl-1-oxopropyl)-L-proline.
Example 33
1,1'-[Dithiodi-(l-D-3-mercapto-2-methyl-1-oxopropyl)]-
_s[(trans)-4-methylthio-L-proline]
The product of Example 21 is treated with iodine
in ethanol according to the procedure described in
Example 24 to give 1,1'-[dithiodi-(1-D-3-mercapto-2-
methyl-l-oxopropyl)]bis[(trans)-4-methylthio-L
proline].
4~ 30 HAl 6 9 a
-46-
Example 34
(cis)-l-[D-3-(Benzoylthio)-2-methyl-1-oxopropyl]-4-
methylthio-L-proline
Interaction of equivalent quantities of
(cis)-4-methylthio-L-proline (J. Amer. Chem. Soc., 79,
185 (1957)) and D-3-(benzoylthio)-2-methyl-propionyl
c~loride according to the procedure of Example 3
gives (cis)-l-[D-3-(benzoylthio)-2-methyl-1-oxo-
propyl]-4-methylthio-L-proline.
Example 35
(trans)-l-[D~3-(Phenylacetyl)-2-methyl-1-oxopropyl]-
4-methylthio-L-proline
Interaction of equivalent quantities of (trans)-
4-methylthio-L-proline (J. Amer. Chem. Soc., 79,
185 (1957)) and D-3-(phenylacetylthio)-2-methylpropionyl
chloride according to the procedure of Example 3
gives (trans)-l-[D-3-(phenylacetyl)-2-methyl-1-oxo-
propyl]-4-methylthio-L-proline.
Example 36
20 (cis)-4-(4-Fluorophenoxy)-l-(D-3-mercapto-2-methyl-1-
oxopropyl)-L-proline
a) (cis)-4-(4-Fluorophenoxy)-L-proline
To a solution of 8.4 g. (0.024 mole) of
N-carbobenzoxy-trans-4-hydroxy-L-proline, benzyl ester
25 [Baer et al., Can. J. Biochem. & Phys., 37, 583
(1959)], 4.0 g. (0.036 mole) of 4-fluorophenol and
9.27 g. (0.036 mole) of triphenylphosphine in 75 ml.
of dry tetrahydrofuran there is addeddropwise over one
hour 6.2 g. (0.036 mole) of diethylazodicarboxylate
in 25 ml. of tetrahydrofuran. The solution is
~ 30 HA169a
-47-
allowed -to stir overnight at room temperature. The
mixture is evaporated to dryness and 100 ml. of ether
is added to the residue. A precipitate of triphenyl-
phosphine and diethylazodicarboxylate is filtered
off Column chromatography (silica gel) separates
out 8.1 g. of a mixture containing about 70%
N-carbobenzoxy-cis-4-(4-fluorophenoxy~-L-proline,
benzyl ester.
A solution of 7.5 g. of the above benzyl
ester containing mixture is hydrogenated at 1
atmosphere (room temperature) with 0.8 g. of
10~ Pd/C. A white precipitate forms during the
reaction. After uptake of hydrogen ceases, the mixture
is filtered and the filter cake leached with three
125 ml. portions of hot methanol. The methanol
solution is evaporated to dryness to yield 3.2 g.
of cis-4-(4-fluorophenoxy)-L-proline; m.p. 235-236 .
Anal. Calc 11 12 3 / 2
C, 57.14; H, 5.48; N, 6.06; F, 8.22
Found: C, 56.94; H, 5.19; N, 5.94; F, 7.97.
b) l-[D-3-(Acetylthio)-2-m_thyl-1-oxopropyl]-
cis-4-(4-fluorophenoxy)-L-proline
To a suspension of 2.25 g. (0.01 mole) of
cis-4-(4-fluorophenoxy)-L-proline in 125 ml. of
dry pyridine at room temperature there is added
1.0 g. (0.01 mole) of triethylamine and 2 g.
(0.011 mole) of D-3-(acetylthio)-2-methylpropionyl-
chloride. After stirring overnight at room tempera-
ture the mixture is evaporated to dryness. The
residue is taken up in water, covered with ether and
~433~ IIA169a
-48-
acidified with 10~ hydrochloric acid. The water layer
is repeatedly extracted with ether, the ether layers
are combined, washed with water, dried (Na2SO4) and
evaporated to dryness to yield 3.9 g. of residue.
The residue is chromatographed on 250 ml. of
silica gel with ether to yield a fraction containing
the desired product. The column is washed with
methanol and the methanol washing is rechromatographed
on a short silica gel column to yield more product.
This procedure is repeated once more to yield a total
of 1.2 g. of pure 1-[D-3-(acetylthio)-2-methyl=1-
oxopropyl]-cis-4-(4-fluorophenoxy)-L-proline.
c? (cis)-4-(4-Fluorophenoxy)-1-(D-3-mercapto-2-
methyl-l- oxopropyl)-L-proline
1.2 g. of 1-[D-3-(aeetylthio)-2-methyl-1-
oxopropyl]-cis-4-(4-fluorophenoxy)-L-proline is
dissolved in 25 ml. of methanol and treated with 5 ml.
of coneentrated ammonia under argon for 40 minutes.
The volatiles are stripped off and the residue is
eovered with ethyl acetate. The water layer is
acidified with 10~ hydrochloric acid. The layers
are separated and the aeid layer is washed with ethyl
acetate. The combined organic layers are stripped with
water (2x), saturated sodium chloride solution (2x),
and dried (Na2SO4). The solvent is stripped off to
yield 1.1 ~. of a solid foam residue of cis-4-(4-
fluorophenoxy)-l-(D-3-mercapto-2-methyl-1-oxopropyl)-L-
proline.
Anal. Cale d- for Cls 18 4 / 2
C, 54.05; H, 5.70; N,4.20; F, 5.70; S, 9.60
~4~30 HA169a
-49-
l~ound: C, 54.04; Il, 5.71; N, 4.05; F, 5.40; S, 9.61.
Thin layer chromatography showed the product at Rf 0.30
as detected by UV-light, SH reagent (yellow spot)
and vanillin (yellow spot). [a]D -80 (c, 1~ in
chloroform).
Example 37
1-(3-Mercapto-l-oxopropyl)-cis-4-phenoxy-L-proline
a) ~cis)-4-Phenoxy-L-proline
Following the procedure of Example 36(a) but
substituting an equivalent amount of phenol for the
4-fluorophenol one obtains (cis)-4-phenoxy-L-proline.
b) l-[3-(Acetylthio)-l-oxopropyl]-cis-4-phenoxy-L-
proline
The (cis-4-phenoxy-L-proline is reacted with a
solution of 3-acetylthiopropionyl chloride ln the
presence of sodium carbonate according to the pro-
cedure of Example 1 to yield 1-[3-(acetylthio)-1-
oxopropyl]-cis-4-phenoxy-L-proline.
c) 1-(3-.~ercapto-1-oxopropyl)-cis-4-phenoxy-L-proline
Hydrolysis of 1-[3-(acetylthio)-1-oxopropyl]-
cis-4-phenoxy-L-proline with an aqueous ammonia
solution according to the procedure of Example 2
yields l-(3-mercapto-1-oxopropyl)-cis-4-phenoxy-L-
proline,
Example 38l-(D-3-Mercapto-2-methyl 1-oxo~ropyl)-cis-4-(4-methyl-
benzyloxy)-L-proline
Following the procedure of Example 36 but
substituting an equivalent amount of 4-methylbenzyl
1~4~0 HA169a
-50-
alcohol for thc 4-fluoropllenoL in p;lrl: (a) one obtaills
l-(D-3-mercapto-2-methyl-1-oxopropyl)-cis-4-(4-metllyl-
benzyloxy)-L-proline.
Example 39
1-(D-3-Mercapto-2-methyl-l-oxopropyl)-cis-4-phenethy
oxy-L-proline
Following the procedure of Example 36 but
substituting an equivalent amount of phenethyl alcohol
for the 4-fluorophenol in part (a) one obtains 1-
(D-3-mercapto-2-methyl-1-oxopropyl)-cis-4-phenethyl-
oxy-L-proline.
Example 40
l-(D-3-Mercapto-2-methyl-1-oxopropyl)-cis-4-(3-methyl-
thiophenoxy)-L-proline
Following the procedure of Example 36 but
substituting an equivalent amount of 3-methylthio-
phenol for the 4-fluorophenol in part (a) one obtains
l-(D-3-mercapto-2-methyl-1-oxopropyl)-cis-4-(3-
methylthiophenoxy)-L-proline.
Example 41
(cis)-4-(4-Chlorophenoxy)-l-(D-3-mercapto-2-meth
oxopropyl)-L-proline
Following the procedure of Example 36 but
substituting an equivalent amount of 4-chlorophenol
for the 4-fluorophenyl in part (a) one obtains
(cis)-4-(4-chlorophenoxy)-1-(D-3-mercapto-2-methyl-1-
oxopropyl)-L-proline.
Example 42
1-(2-Mercapto-1-oxoethyl)-cis-4-(4-methoxyphenoxy)-L-
proline
~1~169a
-51-
.1_ (Ci !.) -4- (4-~1ethoxyphenoxy)-L-proline_
~ ollowing the procedure of Example 36 (a)
but substituti.ng an equivalent amount of 4-methoxy-
phenol for the 4-fluorophenol one obtains (cis)-4-
(4-methoxyphenoxy)-L-proline.
b) l-[2-(Acetylthio)-l-oxoethyl]-cis-4-(4-methoxy-
phenoxy)-L-proline
The (cis)-4-(4-methoxyphenoxy)-L-proline is
reacted with a solution of 2-acetylthioacetyl chloride
according to the procedure of Example 1, part (d),
to yield 1-[2-(acetylthio)-1-oxoethyl]-cis-4-(4-
methoxyphenoxy)-L-proline.
c) 1-(2-Mercapto-1-oxoethyl)-cis-4-(4-methox~phe oxy)-
L-proline
Hydrolysis of 1-~2-(acetylthio)-1-oxoethyl]-cis-
4-(4-methoxyphenoxy)-L-proline with an aqueous
ammonia solution according to the procedure of
Example 2 yields 1-(2-mercapto-1-oxoethyl)-cis-4-
(4-methoxyphenoxy)-L-proline.
Example 43
(cis)-4-(4-Fluorophenylthio)-l-(D-3-mercapto-2-
methyl-l-oxopropyl)-L-proline
Following the procedure of Example 36 but
substituting an equivalent amount of 4-fluorophenyl-
mercaptan for the 4-fluorophenol in part (a) one
obtains (cis)-4-(4-fluorophenylthio)-1-(D-3-mercapto-
2-methyl-1-oxopropyl)-L-proline.
~ 3~ IIA169a
-52-
Example 44
1-(D-3-Mercapto-2-methy1-l-oxopropy1)-cis-4-pheny1-
_hio-L-proline
a) N-Carbobenzyloxy-cis-4-phenylthio-L-proline,
methyl ester
Sodium metal (0.85 g., 0.037 mole) is dissolved
in 40 ml. of absolute ethanol. To this there is
added with stirring 3.7 ml. (0.036 mole) of thiophenol
followed by 7.5 g. (0.017 mole) of N-carbobenzyloxy-
trans-4-tosyloxy-L-proline, methyl ester [J. Am.
Chem. Soc., 79, 191 (1957)]. The latter gradually
goes into solution but soon thereafter a solid
product separates. After stirring for 4 hours and
standing overnight at room temperature, the bulk
of the ethanol is removed on a rotary evaporator.
The mostly solid residue is stirred with 120 ml. of
dichloromethane and 60 ml. of water. The layers are
separated (some methanol is added to help break up
emulsions) and the aqueous phase is extracted with
additional dichloromethane ( 2 x 60 ml.). The
combined organic phase are washed with 100 ml. of
saturated sodium chloride solution, dried (MgSO4),
and the solvent evaporated to give 6.5 g. (100%) of
N-carbobenzyloxy-cis-4-phenylthio-L-proline, methyl
ester as a pale yellow viscous oil.
b) N-Carbobenzyloxy-cis-4-phenylthio-L-proline
The methyl ester product from part (a)
(6.5 g., 0.017 mole) is dissolved in 55 ml. of
methanol, treated portionwise at -1 to 4 with
13 ml. (0.026 mole) of 2N sodium hydroxide, stirred
~ 30 ~A169a
-53-
at 0 for one hour, and kept at room temperature for
approximately 16 hours. After removing about half
of the solvent on a rotary evaporator, the cooled
solution is diluted with 100 ml. of water, washed with
60 ml. of ether (wash discarded), layered over with
70 ml. of ethyl acetate, stirred, cooled, and
acidified with 4.8 ml. of 1:1 hydrochloric acid. After
separating, the aqueous phase is extracted with
additional ethyl acetate ( 3 x 40 ml.) and the
combined organic layers are dried (MgSO4) and
evaporated to give S.9 g. of a light yellow
viscous oil. The latter is dissolved in 30 ml. of
ethanol, treated with 1.9 g. of cyclohexylamine in
3 ml. of ethanol. and diluted to 330 ml. with ether.
lS On seeding, the crystalline cyclohexylamine salt
separates. The latter, after cooling for approxi-
mately 16 hours, weighs 5.3 g.; m.p~ 148-151
(s. 135 ). This material is combined with 1.5 g.
of identical product from a previous experiment, stirred
with 200 ml. of boiling acetonitrile, and cooled to
yield 6.3 g. of colorless cylcohexylamine salt; m.p.
152-155 (s. 137 ) [a]D -24 (c, 1~ in ethanol).
This cyclohexylamine salt is suspended in 25 ml.
of ethyl acetate, stirred, and treated with 25 ml. of
N hydrochloric acid. When two clear layers are
obtained, they are separated and the aqueous phase is
extracted with additional ethyl acetate ( 3 x 25 ml.).
The combined organic layers are dried (MgSO4) and the
solvent evaporated to give 5.0 g. (65~) of N-carbo-
ben~yloxy-cis-4-phenylthio-L-proline as a nearly
~IA169a
-54-
colorless, very viscous syrup.
c) (cis)-4-Phenylthio-L-proline hydrobromide
N-Carbobenzyloxy-cis-4-phenylthio L-proline
(4.9 g., 0.014 mole) is treated with 25 ml. of hydrogen
bromide in acetic acid (30-32%), stoppered loosely,
and stirred maynetically. After one hour the orange-
yellow solution is diluted to 250 ml. with ether to
precipitate the product as a heavy oll which gradually
crystallizes on seeding, rubbing and cooling. After
stirring in an ice-bath for one hour, the material
is filtered under nitrogen, washed with ether,
suspended in fresh ether, cooled for approximately
16 hours, and filtered again to give 3.2 g. (77~)
of colorless solid (cis)-4-phenylthio-L-proline
hydrobromide; m.p. 106-109 (s. 99), [a]D -3
(c, 1% in methanol).
d)_ l-[D-3-(Acetylthio)-2-methyl-1-oxopropyl]-cis-4-
phenylthio-L-proline
Interaction of 3.0 g. (0.0094 mole) of (cis)-4-
phenylthio-L-proline hydrobromide and 2.0 g. (0.011
mole) of D-3-acetylthio-2-methylpropionyl chloride
in 25 ml. of water as described in Example 1, part (d)
(using approximately 15 ml. of 20~ soduim carbonate
solution to maintain the pH at 8.0 to 8.4), yields
3.8 g. of a pale yellow viscous oil. The dicyclohexyl-
amine salt (prepared in 30 ml. of ethyl acetateemploying 1.8 g. of dicyclohexylamine) weighs 2.9 g.
(isolated in two crops); m.p. 184-188 (s. 180).
Following trituration with 15 ml. of acetonitrile,
one obtains 2.4 g. of colorless solid dicyclohexyl-
amine salt; m.p. 184-186 (s. 180 ), ~a]D -75
1~169a
-55-
(c, 1~ in ethanol).
This dicyclohexylamine salt is treated wi-th
30 ml. of 10~ potassium bisulfate and extracted into
ethyl acetate as described in Example 1 to yield
2.0 g. (59%) of glass-like 1-~D~3-(acetylthio)-2-
methyl-1-oxopropyl]-cis-4-pllcnylthio-L-proline.
e) l-(D-3-Mercapto-2-methyl-1-oxopropyl)-cis-4-
phenylthio-L-proline
The l-[D-3-(acetylthio)-2-methyl-1-oxopropyl]-
10 cis-4-phenylthio-L-proline (2.0 g., 0.0042 mole) is
treated with 3.5 ml. of concentrated ammonia in
8.5 ml. of water according to the procedure of
Example 2 (the solid ammonium salt of the product
separates from the reaction mixture) to give 1.35 g.
15 (100%) of viscous syrupy 1-(D-3-mercapto-2-methyl-
l-oxopropyl)-cis-4-phenylthio-L-proline, [a]D -43
(c, 1~ in ethanol).
Example 45
l-(D-3-Mercapto-2-methyl-1-oxopropyl)-cis-4-(4-
chloro-henylthio)-L-proline
Following the procedure of Example 44 but
substituting an equivalent amount of 4-chlorophenyl-
mercaptan for the thiophenol in part (a) one obtains
l-(D-3-mercapto-2-methyl-1-oxopropyl)-cis-4-(4-chloro-
Phenylthio)-L-proline~
Example 46
l-(D-3-Mercapto 2-methyl-1-oxopropyl)-cis-4-(3-
trifluoromethylphenylthio)-L-proline
Following the procedure of Example 44 but
substituting an equivalent amount of 3-trifluoro-
HA163a
-56-
methylphenylmercaptan for the thiophenol in part (a)
one obtains l-(D-3-mercapto-2-methyl-1-oxopropyl-
cis-(3-trifluoromethylphenylthio)-L-proline.
E _ ple 47
(cis)-4-(4-llydroxyphenylthio)-1-(3-mercapto-1-
oxopropyl)-L-proline
a) (cis)-4-(4-Acetyloxyphenylthio)-L-proline
_ . _
hydrobromide
Following the procedure of Example 44 (a) to (c)
but substituting an equivalent amount of 4-acetyloxy-
phenylmercaptan for the thiophenol in part (a) one
obtains (cis)-4-(4-acetyloxyphenylthio)-L-proline
hydrobromide.
b) (cis)-4-(4-Acetyloxyphenylthio)-1-[3-(acetylthio)-
lS l-oxopropyl]-L-proline
Interaction of (cis)-4-(4-acetyloxyphenylthio)-
L-proline hydrobromide and 3-acetylthiopropionyl
chloride according to the procedure described in
Exampl~ 1, part (d) yields (cis)-4-(4-acetyloxy-
phenylthio)-1-~3-acetylthio)-1-oxopropyl]-L-proline.
c) (cis)-4-(4-Hydrox~phenylthio)-1-(3-mercapto-1-
oxopropyl)-L-proline
Hydrolysis of (cis)-4-(4-acetyloxyphenylthio)-
1-[3-(acetylthio)-1-oxopropyl]-L-proline with an
aqueous ammonia solution according to the procedure
of Example 2 yields (cis)-4-(4-hydroxyphenylthio)-1-
(3-mercapto-1-oxopropyl)-L-proline.
1~4~33~ 6g~
-57-
Example 48
(cis)-4-Benzyloxy-l-(D-3-mercapto-2-methyl-1-
oxopropyl)-L-proline
Following the procedure of Example 44 but
substituting an equivalent amount of benzyl alcohol
for the thiophenol in part (a) one obtains
(cis)-4-benzyloxy-1-(D-3-mercapto-2-ethyl-1-
oxopropyl)-L-proline.
Example 49
(trans)-1-(3-Mercapto-l-oxopropyl)-3-methylthio-D,L-
proline
a) 1,2-Dehydroproline, t-butyl ester
To a stirred solution of 34.2 g. (0.20 mole)
of proline t-butyl ester in 600 ml. of ether at -5
to 0 is added dropwise over ten minu'es 21.7 g.
(23.9 ml. , 0.20 mole) of freshly prepared t-butyl
hypochlorite [Org. Syn., Coll. Vol. V, 184 (1973)].
During the addition, the temperature is maintained
at -5to 0 . After the addition is complete, the
solution is stirred at this temperature for an
additional five minutes.
To the vigorously stirred solution is added
rapidly (~ 3-5 min.) a solution of 7.8 g. (0.20 mole)
of potassium in freshly distilled dry (CaH2) t- butanol.
After the addition, the temperature of the reaction
mixture is about 18. The reaction vessel is removed
from the cooling bath and stirred for thirty minutes.
The reaction mixture is filtered through Celite
(diatomaceous earth) and the filtrate concentrated n
vacl~. The residue is taken up in ether and washed
o
~1~169a
-58-
with several portions of water. The ether solution
is dried and concentrated in vacuo to 31.6 g. of
yellow liquid. A trace of hydroquinone is added
and the crude product distilled, affording 22.4 g.
of 1,2-dehydroproline, t-butyl ester (66%),
b.p. 60-62/0.1 mm.
b l-Benzyloxycarbonyl-4,5-dihydro-lH-pyrrole-2-
carboxylic acid, t-butyl ester
A solution of 16.9 g. (0.1 mole) of 1,2-dehydro-
proline, t-butyl ester in 70 ml. of dichloromethane is
cooled to -10 under argon. A solution of freshly
distilled benzylchloroformate (14.2 ml., 0.1 mole,
b.p. 62-64 (0.4 mm)) in 70 ml. of dichloromethane is
added dropwise over a period of 30 minutes. After
stirring in the cold for another 30 minutes a
solution of 15.22 g. (0.1 mole) of 1,5-diazabicyclo-
[5.4.0]undec-5-ene in 70 ml. of dichloromethane is
added over a period of 20 minutes. The cooling bath
is then removed and the mixture is stirred at room
temperature for one hour. After washing twice with
cold dilute hydrochloric acid and once with saturated
sodium carbonate solution, the solution is dried in
vacuo to yield 18.2 g. (60~) of l-benzyloxycarbonyl-
4,5-dihydro-lH-pyrrole-2-carboxylic acid, t-butyl
ester as a pale yellow oil.
c) (trans)-l-Benzyloxycarbonyl-3-methylthio-D,L-
proline, t-butyl ester
A solution of 18.2 g. (0.06 mole) of l-benzyl-
oxycarbonyl-4,5-dihydro-lH-pyrrole-2-carboxylic acid,
t-butyl ester in 180 ml. of dry methanol is treated
3(~
IIA169a
~59-
with 3.24 g. (0.06 mole) of sodium methoxide and
cooled in an ice-bath. Methanethiolis bubbled into
the solution slowly for 30 minutes. The mixture is
stirred overnight under argon at room temperature.
Dilute aqueous acetic acid is added until the solution
is slightly acidic. Argon is bubbled through the
solution for one hour before it is taken to near
dryness in vacuo. Ethyl acetate is added and the
solution is washed twice with saturated sodium carbon-
ate solution, dried and freed of solvent ln vacuo
to yield 17 g. of yellow oil. This oil is chromato-
graphed using 300 g. of silica gel and petroleum ether:
ether (4:1) to yield 11.1 g. of (trans)-l-benzyl-
oxycarbonyl-3-methylthio-D,L-proline as a colorless oil.
d) (trans?-3-Methylthio-D,L~proline
lS 8.4 g. (0.024 mole) of (trans)-l-benzyloxy-
carbonyl-3-methylthio-D,L-proline are treated with
45 ml. of 4N hydrobromic acid in acetic acid.
After stirring for one hour at room temperature the
solution is dried ln vacuo. A small amount of water is
added and this is washed twice with ether. The
aqueous solution is applied to a column containing 300
ml. of an ion-exchange resin and water is passed
through until the eluate is no longer strongly acidic.
The product is then eluted with pH 6.5 (aqueous
pyridine acetate) buffer. Fractions positive to nin-
hydrin are combined and lyophilized to give 3.4 g.
(88%) of white fluff. A small sample of this
material is crystallized from methanol to give
(trans)-3-methylthio-D,L-proline; m.p. 196-200
(dec.) (s. 192).
~ 4~3~ HA169a
-60-
Anal. Calc'd. for C6HllO2~S: C, 44.70; 1-l, 6.88;
N, 8.69; S, 19.89
Found: C, 44.53; H, 7.10; N, 8.61; S, 19.95.
e) (trans)-1-[3-(Acetylthio)-l-oxopropyl]-3-methyl-
thio-D,L-proline
3.05 g. (0.01~ mole) of (trans)-3-methylthio-
D,L-proline is dissolved in 19 ml. of lN sodium car-
bonate and diluted with 10 ml. of water. The solution
is cooled in an ice-bath and while stirring rapidly a
solution of 3-acetylthiopropionyl chloride in 20 ml.
of ether is added. The pH is maintained at 8 by
adding lN sodium carbonate. At the end of 30
minutes the pH is holding constant and 45 ml. of
sodium carbonate solution had been added. The layers
are separated andthe aqueous layer is washed once with
ether. The aqueous layer is then acidified with 10%
potassium bisulfate solution and the product is
extracted into ethyl acetate, dried and freed of
solvent in vacuo to give 5.2 g. of oil. The material
is chromatographed on 150 g. silica gel using ethyl
acetate for elution. 3.85 g. of somewhat crude
(trans)-1-[3-(acetylthio)-1-oxopropyl]-3-methylthio-
D,L-proline are obtained.
A small sample is dissolved in ether and convert-
ed to the dicyclohexylamine salt which is therecrystallized from ethyl acetate to give (trans)-l-
[3-(acetylthio)-1-oxopropyl]-3-methylthio-D,L-proline,
dicyclohexylamine salt; m.p. 153-157.
33[V
~IA169a
-61-
Anal. Calc'd. for Cl1H17O4NS (C6 11)2
C, 58.44; H, 8.53; N, 5.83; S, 13.57
Found: C, 58.77; H, 8.57; N, 5.68; S, 13.74.
f) (trans)-l-(3-Mercapto-l-oxopropyl)-3-methylthio-
D,L-proline
2.05 g. (0.007 mole) of (trans)-1-[3-(acetyl-
thio)-l-oxopropyl]-3-methylthio D,L-proline is
cooled in an ice-bath under argon and treated with a
cold argon saturated mixture of 7 ml. of water and
7 ml. of concentrated ammonia. After stirring for
30 minutes at 0 the solution is acidified with
hydrochloric acid. The product is extracted into
ethyl acetate,dried and freed of solvent ~n vacuo
to give 1.85 g. of material which becomes partially
crystalline on standing. Trituration with ether gives
1.0 g. (57%) of white crystalline product. Re-
crystallization from ethyl acetate (5 ml.) gives
0~85 g. of (trans)-1-(3-mercapto-1-oxopropyl)-3-methyl-
thio-D,L-proline; m.p. 89-93 .
20 Anal- Calc'd- for CgH153NS2 C~ 43-35; H~ 6-06;
N, 5.62; S, 25.72
Found: C, 43.35; H, 6.27; N, 5.54; S, 25.91.
~ mple 50
(trans)-l-(D-3-Mercapto-2-methyl-1-oxopropyl)-3-
25 ethylthio-D,L-proline
a) (trans)-3-Ethylthio-D,L-proline
Following the general procedure of Example 49
(a) to (d) but substituting an equivalent amount of
ethyl mercaptan for the methanethiol one obtains
(trans)-3-ethyl-D,L-proline.
-62- HA169a
b) (trans)-l-[D-3-(Acetylthio)-2-methyl-1-oxopropyl)-
3-ethylthio-D,L-proline
Interaction of the (trans)-2-ethylthio-D,L-
proline and D-3-acetylthio-2-methylpropionyl chloride
according to the procedure of Example 3 yields
(trans)-l-[D-3-(acetylthio)-2-methyl-1-oxopropyl]-3-
ethylthio-D,L-proline.
c) (trans)-l-(D-3-Mercapto-2-methyl-1-oxopropyl)-3-
ethylthio-D,L-proline
Hydrolysis of (trans)-l-[D-3-(acetylthio)-2-
methyl-l-oxopropyl]-3-ethylthio-D,L-proline with an
aqueous ammonia solution according to the procedure of
Example 4 yields (trans)-1-(D-3-mercapto-2-methyl-1-
oxopropyl)-3-ethylthio-D,L-proline.
Example 51
(trans)-1-(3-Mercapto-l-oxopropyl)-3-phenylthio-D~L
proline
Following the general procedure of Example 49
but substituting an equivalent amount of thiophenol
for the methanethi~ yields (trans)-1-(3-mercapto-1-
oxopropyl)-3-phenylthio-D,L-proline.
Example 52
(cis)-4-Methoxy-l-(D-3-mercapto-2-trifluoromethyl-1
oxopropyl)-L-proline
a) 3-(4-Methoxybenzyl)thio-2-trifluoromethylpro-
pionyl chloride
A neat mixture of l-trifluoromethylacrylic
acid (3.9 g.) and 4-methoxy~nzylthio(4.3 g.) is
stirred at 100-110 for one hour. The mixture is
allowed to cool to room temperature andthe solid is
.33~
~ 169a
-63-
recrystallized from cyclohexane to yield 3-(4-
methoxybenzyl)thio-2-trifluoromethylpropanoic acid,
m.p. 72-74.
Treatment of this acid with thionyl chloride
yields 3-(4- methoxyben~yl)thio-2-trifluoromethylpro-
pionyl chloride.
b) (cis)-4-Methoxy-l-[D-3-(4-methoxybenzyl _hio-2-
trifluoromethyl-l-oxopropyl]-L-proline
The 3-(4-methoxybenzyl)thio-2-trifluoromethyl-
propionyl chloride is reacted with (cis)-4-methoxy-
L-proline to yield (cis)-4-methoxy-1-[D-3-(4-methoxy-
benzyl)thio-2-trifluoromethyl-1-oxopropyl]-L-proline.
c) (cis)-4-Methoxy-l-(D-3-mercapto-2-trifluoromethyl-
l-oxopropyl)-L-proline
lS The (cis)-4-methoxy-1-lD-3-(4-methoxybenzyl)thio-
2-trifluoromethyl-1-oxopropyl]-L-proline is mixed with
trifluoroacetic acid and anisole and stirred under
nitrogen. The solvents are removed under vacuum to
yield asaresidue (cis)-4-methoxy-1-(D-3-mercapto-2-0 trifluoromethyl-l-oxopropyl)-L-proline.
Example 53
(trans)-4-Methoxy-l-(D-3-mercapto-2-trifluoromethyl-1-
oxopropyl)-L-proline
Following the procedure of Example 52 but
substituting (trans)-4-methoxy-L-proline for the cis
isomer one obtains (trans)-4-methoxy-1-(D-3-mercapto-
~-trifluoromethyl-l-oxopropyl)-L-proline.
3 144~;~V
HA169a
-64-
Example 54
(trans)-4-Ethoxy-l-tD-3-mercapto-2-trifluoromethyl-1-
oxopropyl)-L-proline
a) 3-Acetylthio-2-trifluoromethylpropionyl chloride
S A mixture of thiolacetic acid and 2-(tri-
fluoromethyl)acrylic acid is heated on a steam bath
for one hour and then stored at room temperature for
18 hours. The reaction mixture is distilled in vacuo
to give 3-acetylthio-2-trifluorome-thylpropanoic acid.
Treatment of this acid with thionyl chloride
yields 3-acetylthio-2-trifluoromethylpropionyl ~hloride.
b) ~trans)-4-Ethoxy-l-[D-3-(acetylthio)-2-trifluoro
methyl-l-oxopropyl]-L-proline
Reacting 3-acetylthio-2-trifluoromethylpropionyl
chloride with trans-4-ethoxy-L-proline according to
the procedure of Example 3 yields (trans)-4-ethoxy-1-
[D-3-(acetylthio)-2-trifluoromethyl-1-oxopropyl]-L-
proline.
c) (trans)-4-Ethoxy-l-(D-3-mercapto-2-trifluoromethyl-
l-oxopropyl)-L-proline
Treating (trans)-4-ethoxy-1-[D-3-(acetylthio)-
2-trifluoromethyl-1-oxopropyl]-L-proline with an
aqueous solution of ammonia according to the pro-
cedure of Example 4 yields (trans)-4-ethoxy-1-
(D-3-mercapto-2-trifluoromethyl-1-oxopropyl)-L-
proline.
~1~4~3~ HA169a
-6 ~
Fx~mple 55
1000 tablets each containing 100 mg. of l-(D-
3-mercapto-1-oxopropyl)-trans-4-methoxy-L-proline,
sodium salt, are produced from the following
5 ingredients:
1-(3-mercapto-1-oxopropyl)-trans-
4-methoxy-L-proline, sodium salt 100 g.
Corn starch 50 g.
Gelatin 7 5 g.
Avicel (microcrystalline cellulose) 25 g-
Magnesium stearate 2.5 g.
The l-(D-3-mercapto-1-oxopropyl)-trans-4-
methoxy-L-proline salt 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
press to form 1000 tablets each containing 100 mg.
of active ingredient.
Example 56
Tablets each containing 200 mg. of 1-(D-3-mer-
capto-2-methyl-1-oxopropyl)-trans-4-methoxy-L-proline
are produced as described in Example 55.
Example 57
1000 tablets each containing 2nn mg. of
l-(D-3-mercapto-2-methyl-1-oxopropyl)-cis-4-
methoxy-L-proline, sodium salt, are produced from
the following ingredients:
4~
HA169a
~ 6 ~
l-(D-3-mercapto-2-methyl-1-oxo-
propyl)-cis-4-methoxy-L-proline,
sodium salt So g.
Lactose 25 g.
Avicel 3~ g.
Corn starch 15 g.
Magnesium stearate 2 g.
The l-(D-3-mercapto-2-methyl-l-oxopropyl)-cis-
4-methoxy-L-proline, sodium salt, 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 lO00 130 mg.
tahlets each containing 50 mg. of active ingredient.
The tablets are coated with a solution of Methocel E
15 (methyl cellulose) including as a color a lake
containing yellow #6.
Example 58
Two piece #l gelatin capsules each containing
lO0 mg. of 1-(D-3-mercapto-2 methyl-l-oxopropyl)-
cis-4-methoxy-L-proline, sodium salt, are filled with
a mixture of the following ingredients:
- l-(D-3-mercapto-2-methyl-1-oxo-
propyl)-cis-4-methoxy-L-
proline, sodium salt100 mg.
Magnesium stearate 7 mg.
USP l,actose 193 mg.
4~3~
IIA169a
-67-
I:x~mple 59
An injectable solution is produced as follows:
(trans)-4-methoxy-1-(D-3-mercapto-2-
methyl-l-oXopropyl)-L-proline 500 g-
Methyl paraben 5 g.
Propyl paraben 1 g.
Sodium chloride 25 g.
Water for injection qs. 5
The active substance, prcservatives and
sodium chloride are dissolved in 3 liters of water
Eor injection and then the volume is brought up to
5 liters. The solution is filtered through a
sterile filter and aseptic~lly filled into pre-
sterilized vials which are then closed with
presterili7,ed rubber closures. Each vial contains
5 ml. of solution in a concentration of 100 mg. of
active ingredient per ml. of solution for injection.
The products of each example can be similarly
formulated as in Examples 55-59.
