Note: Descriptions are shown in the official language in which they were submitted.
~ 23 HA162a-b
Halogen Substltuted Mercaptoacylamino Acids
This invention relates to new halogenated
compounds which have the general formula
(I)
R2 ~ ~R'2
~C ~
IR4 l3 H2~ (CHR6)m
R- S -(CH)n- CH -CO CH-COOR
wherein R is hydrogen, lower alkanoyl or
R R'
2 \ C / 2
/\~
14 iR3 H21C (CHR6)m
-S - (CH)n - CH - CO - N CH-COOR
m is l or 2; n is 0 or l;
Rl is hydrogen or lower alkyli
R2 and R'2 each is hydrogen or halgoen;
R3 is hydrogen, lower alkyl or CF3, and also halogen
when n is l;
R4 is hydrogen, lower alkyl or trifluoromethyl;
R6 is hydrogen, and also halogen when m is l;
at least one of R2, R 2' R3, R4 a 6
halogen or CF3 as represented by the symbols and
only R2 and R'2 can both be halogen at the same time.
The asteriskindicates anasymmetric carbon atom.
~ HA162a-b
The invention in its broadest aspects relates to
halogenated derivatives of mercaptoacyl proline and
mercaptoacyl pipecolic acids having the formula I
above.
With respect to the prolines (when m is 1) two
preferential groups of compounds within formula
are those having the following formulas
(II)
R2 R5
i4 l3
R- S -(CH)n CH - CO - N COOR
wherein R is hydrogen. lower alkanoyl or
R2 X 5
IR4 ¦3 ~ ¦
-S - (CH)n - CH CO - N COOR
Rl is hydrogen or lower alkyl;
R2 and R5 each is hydrogen or fluorine;
R3 and R4 each is hydrogen or trifluoromethyl,
one being hydrogen and the other trifluoro-
methyl; and
n is 0 or 1;
(III)
R2 R5
R4 R3
R - S (CH)n- CH - CO - N COOR
,~3
~ ~ ~ ~ HA162a-b
wherein R and Rl have the same meaning
as defined above for formula II;
R2 and R5 each is hydrogen or halogen;
R3 is hydrogen, halogen or lower alkyl,
5 R3 being halogen when both R2 and R5
are hydrogen, R3 being other than halogen
when R2 or R5 is halogen;
R4 is hydrogen; and
n is 0 or 1;
and basic salts of said compounds of formula II and
III, respectively.
Thus in the case of formula II, when n is 0
and R2 and R5 are both hydrogen, R3 is trifluoromethyl.
When n is 1, either R3 or R4 is trifluoromethyl and
the other is hydrogen. That is to say there is one
trifluoromethyl group in the acyl side chain of the
molecule. It is on the carbon ~ to the carbonyl
group (R3 = CF3) when n is 0. It is on either the
carbon a to the carbonyl group (R3 = CF3, R4 = H)
or on the carbon ~ to the carbonyl group (R3 = H,
R4 = CF3) when n is 1, the other of the pair of
symbols (R3, R4) is then hydrogen. When either
R3 or R4 is trifluoromethyl, R2 and R5 each is
hydrogen or halogen.
In the case of formula III, preferably one or
both of R2 and R5 are halogen and R3 and R4 each is
hydrogen or lower alkyl, or both R2 and R5 are
hydrogen, R3 is halogen, preferably chlorine or
bromine, and R4 is hydrogen.
Preferred particularly are those compounds of
formula I wherein R is hydrogen or lower alkanoyl,
~ 7~3 ~lA162a-b
especially hydrogen or acetyl; Rl is hydrogen or
lower alkyl, especially hydrogen; R2 and R5 each is
hydrogen or halogen, especially hydrogen or fluorine;
R3 and R4 each is hydrogen, trifluoromethyl or lower
alkyl, one of R3 or R4 being trifluoromethyl and the
other hydrogen when R2, R5 and R6 are all hydrogen;
and n is 0 or 1, especially 1.
One or two halogens can be present on the pyrro-
lidine ring. A single halogen can be on either the
carbon in the 3-position or the carbon in the 4-
position. Two halogens can be present in the 4-position
and preferably they are the same. Fluorine is pre-
ferred on this ring, especially one or two fluorine
atoms on the carbon in the 4-position.
In the case of the pipecolic acids (m is 2),
those compounds of formula I are preferred wherein
R is hydrogen or lower alkanoyl, especially hydrogen
or acetyl; Rl is hydrogen or lower alkyl, especially
hydrogen; R2 and R'2 each is hydrogen or halogen
especially hydrogen or fluorine; one of R3 and R4
is CF3 and the other is hydrogen; n is 0
or 1, especially 1. R2 and R'2 can independently be
hydrogen or halogen, especially fluorine. When
R3 or R4 is CF3, both R2 and R'2 are prefera~ly
hydrogen.
The L-configuration for the prolines or pipecolic
acids is especially preferred.
The lower alkyl groups represented by any of the
variables include straight and branched chain hydro-
carbon radicals from methyl to heptyl, for example,
~ 23 HA162a-b
methyl, ethyl, propyl, isopropyl, butyl, isobutyl,
t-butyl, pentyl, isopentyl and the like. The Cl-C4
members, especially Cl and C2 members, are preferred.
The lower alkanoyl groups are those having the
acyl radicals of the lower (C2-C7) fatty acids, for
example, acetyl, propionyl, butyryl and the like.
Similarly, those lower alkanoyl groups having up to
four carbons, and especially acetyl, are preferred.
The halogens are the four common halogens,
chlorine, bromine and fluorine being preferred,
especially fluorine.
The products of formula I can be produced by
various methods of synthesis.
In general, these compounds can be synthesized
by coupling ~he acid of the formula
(IV)
14 IR3
R - S - (CH)n - CH COOH
to the amino acid of the formula
(V) R2 R~2
\C
H2CI (CHR6)m
HN---- CH COORl
by any method which can be used to form amide bonds.
See, for example, "Methoden der Organischen Chemie"
(Houben-Weyl) part I, p. 376 et seq., part III, p. 1
et seq. (1974).
.
~ Z~23 HA16~a-b
The acids of formula IV, when n is 1 can be
obtained by the addition of a thioacid R-SH to a
suitably substituted acrylic acid. As a temporary
protection of the mercapto group in compounds of
formula IV, R can be a p-methoxy-benzyl group. This
group is then removed with trifluoroacetic acid and
mercuric acetate. The acids of formula IV, when n is
0, are obtained by a displacement reaction using a
thioacid R-SH and a 2-halo acid.
According to one method, preferred when n
is 0, an acid of formula V is coupled with a halo-
alkanoic acid of the formula
(VI)
Rl4 l3
X - (CH)n - CH-COOH
wherein X is halogen, preferably chlorine or bromine,
by one of the known procedures in which the acid VI is
activated, prior to reaction with the acid V, involving
formation of a mixed anhydride, symmetrical anhydride,
acid chloride, active ester, or use of Woodward
reagent K, EEDQ (N-ethoxy-carbonyl-2-ethoxy-1,2-di-
hydroquinoline) or the like.
The product of this reaction is a compound of
the formula
(VII) R2 X R'~
R4 13 H2C (CHR6)m
X (CH)n - CH -CO - N OORl
1~3L24723 1-~16 2 a - b
This product is subjected to a displacement reaction
with the anion of a thioacid of the formula
(VIII)
R7-CO-SI~
wherein R7 is lower alkyl yielding a product
of the formula
(IX) X
R4 IR3 H21 I CHR6)m
R7- CO -S - (CH)n CH- CO- N COOR
which can then be converted to the product
(X) 2 ~ Rl2
IR4 IR3 H21C ~ (CHR6)m
HS (CH)n C~- CO -N COOR
by conventional aIkaline hydrolysis or ammonolysis. When Rl
is an ester group (i.e., Rl is lower alkyl, obtained when an ester
of the starting acid V is used),the ester group can be
removed by conventional techniques. For example,
when Rl is tert-butoxy or tert-amyloxy, treatment
of the es~er of formula IX or X with trifluoroacetic
acid and anisole will give the corresponding free acid.
When other alkoxy groups are present alkaline hydrolysis
will yield the corresponding acid.
When an acid of formula V is used as starting
material, or the final product is obtained as the free
carboxylic acid, this acid can 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.
~24~23
8 HA162a -b
According to another variation, an ester,
preferably the methyl or t-butyl ester, of formula
V, in an anhydrous medium such as dichloromethane,
tetrahydrofuran, dioxane or the like, is treated
with an acylthioalkanoic acid of the formula
(XI)
R4 13
R7 CO- S -(CH)n- CH - COOII
in the presence of dicyclohexylcarbodiimide,
N,N'-carbonylbisimidazole, ethoxyacetylene,
diphenylphosphoryl azide or similar coupling
agents at a temperature in the range of about
0 to 10 C. The ester group can then be removed9
for example, by treatment with trifluoroacetic
acid and anisole at about room temperature to
yield the free acid (Rl = H).
A variation, preferred when n is 1, R4 is CF3
and R3 is H, is to react a thioacid of formula VIII
with an acrylic acid derivative of the formula
(XII)
R4 R3 R2 R '2
~ H2 ~ CHR6)m
CH _CH- C N- COORl
instead of with the compound of formula VII, and
then continue as described above. The compounds
of formula XII are obtained from 3-trifluoromethyl-
acrylic acid and an ester of formula V by the
method described in Example 14 below.
~24723
9 HA162a-b
Compounds of formula I wherein R is
R2 R~2
~4 l3 H2C ~C~R6)m
-S - (CH)n- CH - CO - N COORl
are produced by direct oxidation of a compound of
formula I in which R is hydrogen, e.g., with iodine,
to obtain the symmetrical bis compound.
Halogenated ~mpounds of formula V which are
used as starting materials can be produced by
methods known in the art, e.g., Biochemistry 4,
2509 (1965), Aust. J. Chem. 20, 1493 (1967),
J. A~er. Chem. Soc. 86, 4709 (1964), J. Med Chem.
20, 1176 (1977).
Products of formula I have one or more asym-
metric centers, the basic being 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 aboved described
synthesis can utilize the racemate or one of the
enantiomers as starting material. When the
racemic 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 basic asymmetric
carbon constitutes the preferred isomeric form.
The compounds of this invention form basic salts
with various inorganic and organic bases which
are also within the scope of the invention. Such
~L~L24~23
10 HA162a-b
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 salts, benzathine,
N-methyl-D-glucamine, 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.
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
lS providing the desired salt ion, 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.
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 are useful as
hypotensive agents. They inhibit the conversion of
the decapeptide angiotensin I to angiotensin II
and therefore are useful in reducing or relieving
_ _
.
,: :
~l2'~23
11 ~162a-b
angiotensin related hypertension. The action of
the enzyme renin on angiotensinogen, a`pseudoglobulin
in blood plasma, produces angiotensin I. Angiotensin
I is converted by angiotensin converting enzyme
(ACE) to angiotensin II. The 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
angiotensinogen ~ (renin) ~ angiotensin I -~
~ACE) ~ angiotensin II sequence by inhibiting
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 combination
of compounds of formula I or a physiologically
acceptable salt thereof, angiotensin dependent
hypertension in the species of mammal suffering
thereform is alleviated. A singledose, or prefera-
bly two to four divided daily doses, provided on a
basis of about 0.1 to 100 mg. per kilogram per
day, preferably about 1 to 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. ~.Waugh
and B. Rubin, Proc. Soc. Exp. Biol. Med. 143
(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
12 HA162a-b
formulating in compositions such as tablets, capsules
or elixirs for oral administration or in sterile
solutions or suspensions for parenteral administration.
About 10 to 500 mg. 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 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
~0 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 be present as coatings or to
otherwise modify the physical form of the dosage
unit. For instance, tablats 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.
:
723
13 HA162a-b
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.
The following examples are illustrative of the
invention and constitute especially preferred
embodiments. All temperatures are in degrees
Celsius.
Example 1
3-Acetylthio-2-trifluorome~
A mixture of thiolacetic acid (50 g.) and
2-(trifluoromethyl)acrylic acid [M.W. Buxton, et al.
J. Chem. Soc., 366 (1954)] (66 g. ) is heated on
the steam bath for one hour and then stored at
room temperature for eighteen hours. The
reaction mixture is distilled in vacuo to give
3-acetylthio_2-trifluOromethylpropanoic acid.
Example 2
1-(3-Acetylthio-2-trifluoromethylpropanovl)-L-proline
tert-butyl ester
L-proline tert-butyl ester (5.1 g.) is dissolved
in dichloromethane (40 mg.) and the solution is
stirred and chilled in an ice bath. Dicyclohexyl-
carbodiimide (6.q g.) dissolved in dichloromethane
(15 ml.) is added followed immediately by a
solution of 3-acetylthio-2-trifluoromethylp~opanoic
acid (6.5 g.) in dichloromethane (5 ml.). After
fifteen minutes stirring in the ice bath and
sixteen hours at room temperature, the precipitate
formed is filtered off and the filtrate is
. .
' ;' -
14 HA162a-b
concentrated to dryness in vacuo. The residue is
dissolved in ethyl acetate and washed nèutral. The
organic phase is dried over magnesium sulfate and
concentrated to dryness in vacuo to give l-(3-acetyl-
thio-2-trifluoromethylpropanoyl)-L-proline tert-butyl
ester.
Example 3
1-(3-Acetylthio-2-trifluoromethylpropanoyl)-L-proline
1-(3-Acetylthio-2-trifluoromethylpropanoyl)-L-
proline tert-butyl ester (8 g.) is dissolved in a
mixture of anisole (55 ml.) 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 to give 1-(3-acetylthio-2-trifluoromethyl-
propanoyl)-L-proline.
Example 4
1-(3-Mercapto-2-trifluoromethylpropanoyl)-L-proline
1-(3-Acetylthio-2-trifluoromethylpropanoyl)-L-
proline (4 g.) is dissolved in a mixture of water
(8 ml.) and concentrated ammonia (8 ml.) under a
blanket of nitrogen. After twenty-five minutes
stirring at room temperature, the reaction mixture
is chilled, acidified and extracted with ethyl
acetate. The organic layer is concentrated to
dryness in vacuo to yield l-(3-mercapto-2 trifluoro-
methylpropanoyl)-L-proline.
Example 5
2-Bromo-3,3,3-trifluoropropanoic acid
3,3,3-Trifluoroalanine (88 g.) is dissolved in a
mixture of potassium bromide (250 g.) and 2.5 N
sulfl~ric acid (1.240 ml.). The solution is chilled
~247`23
15 HA162a~b
to 0 with an ice-salt bath and sodium nitrite
(65.5 g.) is added in small portions over a one
hour period with vigorous stirring. The reaction
mixture is stirred in the cooling bath for another
hour and then extracted with ether. The organic
layer is washed with water, dried over magnesium
sulfate and concentrated to dryness in vacuo to yield
2-bromo-3,3,3-trifluoropropanoic acid.
Example 6
2-Bromo-3,3,3-trifluoropropanoic acid chloride
A solution of 2-bromo-3,3,3-trifluoropropanoic
acid (5 g.) in thionyl chloride (5 ml.) is refluxed
in the steam bath for two hours. The excess thionyl
chloride is removed in vacuo, and the residue
distilled under reduced pressure to yield 2-bromo-
3,3,3-trifluoropropanoic acid chloride.
Exam~le 7
1-(2-Acetylthio-3~3~3-trifluoropropanoyl)-L-proline
To a solution of L-proline (5.75 g.) in lN
sodium hydroxide (50 ml.), chilled in an ice-water
bath, 2-bromo-3,3,3-trifluoropropanoic acid
chloride (12 g.) is added and the mixture is
vigorously stirred at room temperature for three
hours. A solution of thiolacetic acid (4 ml.) and
potassium carbonate (4.8 g.) in water (50 ml.) is
added and the mixture is stirred at room temperature
for sixteen hours. After extraetion with ethyl
acetate, the aqueous layer is acidified with
concentrated hydrochloric acid and extracted
again with ethyl acetate. This last organie phase
is dried over maynesium sulfate and concentrated
to dryness in vacuo. The residue is ehromatographed
23
16 HA162a-b
on a silica gel column with a mixture of benzene-
acetic acid (7:2) to yield 1-(2-acetylthio-3,3,3-
trifluoropropanoyl)-L-proline.
Example 8
1-(2-Mercapto-3,3,3-trifluoropropanoyl)-L-proline
1-(2-Acetylthio-3,3,3-trifluoropropanoyl)-L-
proline (4 g.) is dissolved in a mixture of water
(8 ml.) and concentrated ammonia (8 ml.) under a
blanket of nitrogen. After thirty minutes at room
temperature, the reaction mixture is acidified
and extracted with ethyl acetate. The organic phase
is dried over magnesium sulfate and concentrated to
dryness in vacuo to yield l-(2-mercapto-3,3,3-tri-
fluoropropanoyl)-L-proline.
Example 9
1,1'-[Dithiobis-(2-trifluoromethyl-3-propanoyl)]-bis-
L-proline
1-(3-Mercapto--2-trifluoromethylpropanoyl)-L-
proline (1 g.) is dissolved in water adjusted to
2C pH 7 with N sodium hydroxide. An ethanolic solution
of iodine is added dropwise while maintaining the pH
between 6 and 7 by careful addition of N sodium
hydroxide. When a permanent yellow color is obtained,
the addition o iodine is stopped and the color is
discharged with sodium thiosulfate. The reaction
mixture is acidified and extracted with ethyl
acetate. The organic layer is dried over
magnesium sulfate and concentrated to dryness to
yield l,l'-[dithiobis-(2-trifluoromethyl-3-propanoyl)~-
bis-L-proline.
,.... .
723
17 IIA1~2a-b
_ample 10
1-(3-~cetylthio-2-trifluoromethylpropanoyl)-L-proline
sodium salt
A suspension of 1-(3-acetylthio-2-trifluoro-
methylpropanoyl)-L-proline (1 g.) in water (10 ml.)
is adjusted to pH 8 by addition of normal sodium
hydroxide. The resulting solution is freeze dried
to yield l-(3-acetylthio-2-trifluoromethylpropanoyl)-
L-proline sodium salt.
Example 11
1-(3-Acetylthio-2-trifluoromethylpropanoyl)-4,4-
difluoro-L-proline
To a solution of 4,4-difluoro-2-proline
(7.5 g.) in N sodium hydroxide (50 ml.) chilled
in an ice-water bath, 3-acetylthio-2-trifluoro-
methylpropanoic acid chloride (prepared from
3-acetylthio-2-trifluoromethylpropanoic acid and
thionyl chloride by the procedure of Example 6,)
~2 g.)is added and the mixture is vigorously stirred
at room temperature for two hours. After acidifica-
tion with concentrated hydrochloric acid, the aqueous
mixture is extracted with ethyl acetate. The organic
phase is dried over magnesium sulfate and concentra-
ted to dryness to yield l-(3-acetylthio-2-trifluoro-
methylpropanoyl)-4,4-difluoro-L-proline.
Example 12
1-(3-Mercapt.o-2-trifluoromethxlpropanoyl)-4,4-
difluoro-L-proline
By substituting 1-(3-acetylthio-2-trifluoromethyl-
propanoyl)-4,4-difluoro-L-proline for the 1-(3-
acetylthio-2-trifluoromethylpropanoyl)-L-proline in
the procedure of Example 4, 1-(3-mercapto-2-trifluoro-
_ _
23
18 IIA162a-b
methylpropanoyl)-4,4-difluoro-L-proline is obtained.
Example 13
1,1'-[Dithlobis-(2-trifluoromethyl-3-propanoyl)~-
bis-4,4-difluoro-L-proline
By substituting 1-(3-mercapto-2-trifluoro-
methylpropanoyl)-4,4 difluoro-L-proline for the
1-(3-mercapto-2-trifluoromethylpropanoyl)-L-
proline in the procedure of Example 9, 1,1-
~dithiobis-(2-trifluoromethyl-3-propanoyl)]-bis-
4,4-difluoro-L-proline is obtained.
Example 14
1-(4,4,4-Trifluoro-2-butenoyl)-L-proline
Boric anhydride (7.0 g., 0.1 mole)(prepared
by fusing boric acid in a platinum crucible and
crushing under nitrogen)is combined with ethyl
3-hydroxy-4,4,4-trifluorobutanoate (32.2 g.,
0.173 mole) in a 50 ml. flask equipped with a
Dean-Stark trap and the mixture is heated at 180
with a salt bath until all of the anhydride
dissolves (6 hours). The heat is increased to
350 during which time 23 ml. of distillate
accumulates in the trap. The distillate is
returned to the reaction flask and the heating
step is repeated. This process is repeated 4 times to
assure complete dehydration of the hydroxy ester.
The distillate is dissolved in petroleum ether,
dried over phosphorous pentoxide and distilled,
yielding 10 g. of 4,4,4-trifluoro-2-butenoic
acid ethyl ester (b.p. 115-120 ) and 650 mg. of
4,4,4-trifluoro-2-butenoic acid (b.p. 150 ,
53-55 recrystallization from pentane).
~12 ~23
19 HR162a-b
The ester is combined with 10% aqueous sodium
hydroxide (24 ml.) and stirred at 25 for 6 hours.
The mixture is diluted with water and extracted with
methylene chloride to remove unchanged material.
The aqueous layer is adjusted to pH 3 with concentra-
ted hydrochloric acid and this mixture is extracted
with methylene chloride ( 3 x 50 ml.). The organic
layers are combined, dried over sodium sulfate,
concentrated and the residue dis-tilled giving crysta-
lline 4,4,4-trifluoro-2-butenoic acid (b.p. 145-153 ).
Recrystallized from pentane, the acid melts at
54-55 , yield 4.6 g.
A mixture of the 4,4,4-trifluoro-2-butenoic
acid (4.91 g., 35 mmole), hydroxybenzotriazole
(4.73 g., 35 mmole), L-proline-t-butyl ester
(6.00 g., 35 mmole) and dicyclohexylcarbodiimide
(7.22 g., 35 mmole) in methylene chloride (200 ml.)
is stirred under nitrogen overnight at room tempera-
ture. The mixture is filtered, the filtrate washed
with 5~ sodium bisulfate (2 x 50 ml.) and saturated
sodium bicarbonate (2 x 50 ml.), dried over sodium
sulfate and concentrated to yield an oil. This is
dissolved in ether and the solution is chilled and
filtered free of precipitate. The filtrate is
concentrated, yielding a solid ( m.p. 95-100,
8.7 g.) which shows a single spo-t by TLC (silica
gel EM 50/50, EtoAc~CH2C12, Rf = .85).
A mixture of the above obtained 1-(4,4,4-tri-
fluoro-2-butenoyl)-L-proline t-butyl ester (4.0 g.,
13.6 mmole) is mixed with trifluoroacetic acid
(60 ml.) and anisole (13 ml.) and stirred under
nitrogen for one hour. The solvents are removed
20 H~162a-b
under vacuum and the residue, dissolved in ether
(10 ml.), is poured into pentane (500 ml.). This
precipitatiOn technique is repeated and the
residue allowed to stand at 0 for 72 hours during
which time crystallization occurs. The 1-(4,4,4-
trifluoro-2-butenoyl) L-proline is recrystallized
from ethyl acetate-hexane; yield 2.48 g., m.p.
119-120 .
Example 15
1-(3-Mercapto-4,4,4-trifluorobutanoyl)-L-proline
Thiolacetic acid (1.5 ml.) is combined with
1-(4,4,4-trifluoro-2-butenoyl)-L-proline (720 mg.,
3 mmole) under argon and the mixture stirred
at room temperature overnight. The excess thiol-
acetic acid is removed under vacuum and the
residual l-(3-acetylthio-4,4,4-trifluorobutanoyl)-
L-proline is mixed with aqueous ammonia (15 ml.
conc. NH3 ~ 15 ml. water) and stirred for 2
hours at room temperature. The mixture is then
diluted with ice and acidified with concentrated
hydrochloric acid. The acid mixture is extracted
with methylene chloride (3 x 50 ml.), the extracts
dried over sodium sulfate and concentrated to
yield an oil. This is purified by dissolving in
water (double distilled), treating the solution
with carbon and filtering through a millipore filter
(0.4 m followed by 0.08 m). Lyophilization of
this solution gives 700 mg. of 1-(3-mercapto-4,4,4-
trifluorobutanoyl)-L-proline as a colorless glass.
Rf (benzene:acetic acid 7:1) 0.24
,, ,~ .
23
21 HA162a~b
Example 16
3~Acet lthio-4,4,4-trifluorobutanoic acid chloride
Y
By substituting 4,4,4-trifluoro-2-butenoic acid
for the 2-trifluoromethyl acrylic acid in the -
procedure of Example 1, 3-acetylthio-4,4,4-trifluoro-
butanoic acid is obtained, then chlorinating with
thionyl chloride as in Example 6, 3-acetylthio-4,4,4-
trifluorobutanoic acid chloride is obtained.
Example 17
1-(3-Mercapto-4,4,4-trifluorobutanoyl)-4,q-
difluoro-L-proline
By substituting 1--(3-acetylthio-4,4,4-trifluoro-
butanoic acid chloride for the 3-acetylthio-2-
trifluoromethylpropanoic acid chloride in the
procedure of-Example 11 and then submitting the
product ~to the proced~re of Example 4, 1-(3-mercapto-
4,4,4-tri.fluorobutanoyl)-4,.4-difluoro-L-proline
is obtained.
Example 18
o 1 1'-[Dithiobis-(4,4,4-tri~luoro-3-butanoyl)]-bis-L-
2 ~ _
proline
By substituting 1-(3-mercapto-4,4,4-trifluoro-
butanoyl)-L-Proline for the 1-(3-mercapto-2-trifluoro-
methylpropanoyl)-L-proline in the procedure of
Example 9, 1,1'-[dithiobis-(4,4,4-trifluoro-3-
butanoyl)]-bis-L-proline is obtained.
Example 19
cis-4-Fluoro-L-Proline, hydrobromide
a) N-Carbobenzylox~-4-hydroxy-L-proline, methyl ester
N-Carbobenzyloxy-4-hydroxy-L-proline [12.4 g.
(0.047 mole)] is esterified with diazomethane in
dioxane-ether as described in JACS, 79, 191 (1957).
.1~!L~L~7~ ~
22 HA162a-b
To avoid freezing of the dioxane the addition of
the diazomethane solution is begun at 10 and
completed at 0-2 . The yield of nearly colorless
viscous oil is 14.6 g. (100%).
b) N-Carbobenæyloxy-4~tosyloxy-L-proline, methyl
ester
A stirred solution of 14.5 g. (0.052 mole) of
N-carbobenzyloxy-4-hydroxy-L-proline, methyl ester in
30 ml. of pyridine is treated dropwise at -5 to
-8 with a solution of 11 g. (0.058 mole) of tosyl
chloride in 15 ml. of pyridine. The pale yellow
solution is stored in the cold for 3 days, then
added with stirring to 300 ml. of ice-cold 2 N
hydrochloric acid. The precipitated gum is
extracted with 200 ml. of chloroform. The aqueous
phase is extracted with additional chloroform
(3 x 100 ml.). The organic layers are combined,
dried (MgSO4), and the solvent evaporated to give
a pale yellow viscous oil. The oil is dissolved in
100 ml. of methanol and diluted to 400 ml. with
water to precipitate the product as an oil which
gradually crystallizes on seeding, xubbing, and
cooling: yield 17.4 g. (77%); m.p. 62-65.
Following crystallization from 85 ml. of isopropanol,
the colorless solid N-carbobenzyloxy-4-tosyloxy-
L-proline, methyl ester weighs 15.9 g. (70%);
m p 67-69; [a]26 _30 ( c = l; methanol).
c) cis-N-CarbobenzvloxY-4-fluoro-L-proline,
methyl ester
A stirred suspension of 19.1 g. (0.044 mole)
of N-carbobenzyloxy-4-tosyloxy-L-proline, methyl
ester in 100 ml. of redistilled diethylene glycol
is treated at 42 (under argon) with 19.1 g.
.: :
"
7;~3
23 l~ 2a-b
(0.33 mole) of anhydrous potassium ~luoride and
the resulting solution is heated at 81`84 for
20 hours. After cooling, the light yellow solution
is worked up to give 18.6 g. (100%) of cis-N-
carbobenzyloxy-4-fluoro-L-proline, methyl ester as
a light yellow oil.
d) cis-N-Carbobenzyloxy -4-fluoro-L-proline
The cis-N-carbobenzyloxy-4-fluoro-L-proline,
methyl ester (18.4 g., approximately 0.044 mole)
is dissolved in 140 ml. of methanol, treated drop-
wise at -1 to 4 with 33 ml. (0.066 mole) of
2 N sodium hydroxide, then kept at 0 for one hour,
and at room temperature overnight. After removing
about 1/2 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, washed with 100 ml. of
saturated sodium chloride solution, dried (MgSO4)
and the solvent evaporated to give 13.8 g. of a
pale yellow viscous oil. The latter is dissolved in
60 ml. of ethanol, treated with 5.1 g. of cyclo-
hexylamine in 10 ml. of ethanol and diluted to
900 ml. with ether. On seeding and rubbing,
crystalline cis-N-carbobenzyloxy-4-fluoro-L-proline,
cyclohexylamine salt separates: weight after cooling
overnight, 11.0 g., m.p. 180-183 (s. 175 ).
Following crystallization from 70 ml. of ethanol,
the colorless solid weighs 7.6 g., m~p. 185-187,
[a]D ~40 ~c = 1; methanol).
. :...... - -
Z3
24 ~l~162a -b
The cyclohexylamine salt is suspended in 75 ml.
of ethyl acetate, stirred, and treated with 45 ml.
of hydrochloric acid. The layers are separated,
the aqueous phase is extracted with additional ethyl
acetate (2 x 75 ml.), then the combined organic
layers are dried (MgSO4), and the solvent evaporated.
The residual free acid, cis-N-carbobenzyloxy-4-
fluoro-L-proline crystallizes when finally dried
at 0.2 mm. and 45 ; yield 5.7 g. (49~); m.p.
116-118 .
e) cis-4-Fluoro-L-proline, hydrobromide
The cis-N-carbobenzyloxy-4-fluoro-L-proline
(5.5 g., 0.021 mole) is treated with 28 ml. of
hydrogen bromide in acetic acid (30-32%), stoppered
looselY, and stirred for one hour. Ether (300 ml.)
is added to the yellow mixture and when the
crystalline product has settled the ethereal liquor
is decanted and the material washed with 300 ml.
of fresh ether by decantation. The product is
finally heated in the steam bath with 70 ml. of
methyl ethyl ketone, cooled for two hours, washed
with cold methyl ethyl ketone and with ether, and
dried in vacuo. The yield of nearly colorless
solid, cis-4-fluoro-L-proline, hydrobromide is
3.8 g. (86%), m.p. 189-191 (dec.), [a]D -19
(c = 1, methanol).
A portion of the crude hydrobromide salt is
converted to the free acid by passing through a
column of Dowex l-X8 ion exchange resin.
,~. .~ .
:
25 HAl62a-b
Example 20
ci~ [l)-3- A_etylthio)-2-1ne~l~yll~ro~ n~ -4-
fluoro-L-prolinc
cis-4-Fluoro-L-proline, hydrobromide (4.5 g.,
0.021 mole) and 4.2 g. (0.023 mole) of D-3-acetyl-
thio-2-methylpropanoic acid chloride are reacted
in 50 ml. of water in the presence of sodium carbonate
to stabilize the pH at 8.0 - 8.2 during the acylation
(approximately 20 minutes). The mixture is worked
up after an additional hour by washing with ethyl
acetate (2 x 50 ml.),layering over with ethyl
acetate, acidifying with hydrochloric acid to pH 2,
saturating with sodium chloride and then separating
the layers. The aqueous phase is extracted with
additional ethyl acetate and the organic layers are
combined, dried and evaporated. The solid residue
from the ethyl acetate evaporation is rubbed under
ether and the evaporation repeated; weight of colorless
product, 5.4 g. (93%), m.p. 146-148 (s.133 )
[~26 -132 (c = l; methanol). The dicyclohexylamine
salt is prepared by adding dicyclohexylamine to the
cis-l-[D-3-(acetylthio)-2-methylpropanoyl-4-fluoro-L-
proline in 70 ml. of ethyl acetate. 8.1 gm. of
salt, which crystallizes out, are obtained, m.p.
202-204 ~s. 187); [a]2 -72 (c = l; methanol).
Crystallization from 90 ml. o~ isopropanol
gives 7.0 g., m.p. 205-207 ~s, 190). [a]26 -74.
A sa~ple recrystallized from ethanol shows no
further change in m.p. of []D
The dicyclohexylamine salt (16.9 g.) is con-
verted back to the free acid by distribution between
10~ potassium bisulfate and ethyl acetate (60 ml.
... . .
;23
26 1lA162a-b
10% KHSO4i 4 x 50 ml. ethyl acetate extractions).
The organic layers are combined and evaporated
to dryness to obtain 4.1 g. (71~) of colorless
free acid, m.p. 154-156 (s. 140 ) [a]D6 -142
(c = 1; methanol).
Example 21
cis-4-Fluoro-l-(D-3-mercapto-2-methyl~roPanoyl)-L-
..
prolinecis-l-lD-3-(Acetvlthio)-2-methylpropanoyl]-4-
fluoro-L-proline (3.9 g., 0.014 mole) is hydrolyzed
in 22 ml. of water containing 9 ml. of concentrated
ammonium hydroxide. The reaction mixture is acidified
with hydrochloric acid and extracted with ethyl
acetate. The organic layer is concentrated to dryness
to give 3.3 g. of glass-like product which slowly
crystallizes when dried at 0.2 mm. and 50 . The
material is triturated with 20 ml. of ethyl acetate
(with slight warming under argon), diluted with
25 ml. of h~xane, rubbed, and cooled overnight (under
argon). Following filtration under argon, washing
with hexane, and drying in vacuo, the colorless solid
cis-4-fluoro-1-(D-3-mercapto-2-methylpropanoyl)-L-
proline weighs 2.8 g. (85~), m.p. 135-137 (s. 129),
[~]26 -116 (c = l; methanol).
Example 22
1-[3-(Acetylthio)-2-chloropropanoyl]-L-proline
(Isomer A)
L-Proline (1.44 g.) and sodium carbonate (667 mg.)
are dissolved in 17 ml. of water and stirred in an
ice bath. To this sodium carbonate (2 g.) in
8.5 mg. of water is added, followed immediately by
3-acetylthio-2-chloropropanoic acid chloride (2.5 g.).
~%3
27 HA162a~b
The ice bath is removed. After 30 minutes a precipi-
tate forms which is solubilized with thè addition
of 17 ml. of water. After a total of 1.5 hours, the
reaction mixture is extracted twice with ethyl acetate.
The aqueous layer is chilled, acidified with concen-
trated hydrochloric acid, saturated with sodium chloride,
extracted into ethyl acetate, dried over magnesium
sulfate and concentrated to dryness in vacuo to obtain
the product as a crude oil, yield 3.3 g.
The oil is applied to a 100 g. silica gel
column and eluted with benzene/acetic acid 7:1 to
yield 2 g. of product which is crystallized from
water to yield 450 mg. of 1-[3-(acetylthio)-2-chloro-
propanoyl]-L-proline, m.p. 111-113 . [a] -170
lS tc = 1; ethanol)
Example 23
1-[3-(Acetylthio)-2-chloroeropanoyl]-L-proline
(Isomer B)
-
The aqueous mother liquors from Example 22 are
lyophilized and chromatographed on silica gel with
benzene/acetic acid 7:1. The fractions containing
the UV absorbing material and shown to be homogensous
by TLC are pooled, concentrated to dryness and
crystallized from water, yield 800 mg., m.p. 90-109
[a]D -4 (c = 2.1; ethanol). The mother liquors
are concentrated to dryness by freeze-drying and the
residual l-[3-(acetylthio)-2-chloropropanoyl-L
proline, (Isomer B) is crystallized from ether-
hexane; yield 380 mg., m.p. 108-110 , [a]D +17.6
(c = 1.25; ethanol).
;1~i 2'~
28 HA162a-b
Example 24
.
1-[3-(Acetylthio)-2-bromopropanovl]-L-proline
,
By substituting 3-acetylthio-2-bromopropanoic
acid chloride for the 3-acetylthio-2-chloropropanoic
acid chloride in the procedure of Example 22,
1-[3-(acetylthio)-2-bromopropanoyl]-L-proline is
obtained, m.p. 109-110 , [a]D -162 (c = 1.39;
ethanol).
~xample 25
cis-4-Chloro-l-(D-3-mercapto-2-methylpropanoyl-L-
proline
By substituting cis-4-chloro-L-proline [Aust.
J. Chem. 20, 1493 (1967)] for the cis-4-fluoro-L-
proline, hydrobromide in the procedure of Example 20,
and then submitting the product to the procedure
of Example 21, cis-1-[D-3-(acetylthio)-2-methyl-
propanoyl-4-chloroproline and cis-4-chloro-1-(D-3-
mercapto-2-methylpropanoyl)-L-proline are obtained.
Example 26
trans-4-Bromo-l-(D-3-mercapto-2-methylpropanoyl)-L
proline
By substituting trans-4-bromo-L-proline lAust.
J. Chem. 20, 1493 (1967)] for the cis-4-fluoro-L-
proline hydrobromide in the procedure of Example 20,
and then submitting the product to the procedure
of Example 21, trans-1-[D-3-(acetylthio)-2-methylpro-
panoyl}-4-bromo-L-proline and trans-4-bromo-1-(D-
3-mercapto-2-methylpropanoyl)-L-proline
are obtained.
Example 27
By substituting cis-4-iodo-L-proline for the
cis-4-fluoro-L-proline hydrobromide in the procedure
., .
.
.
~,
HA16;2a-b
29
of Example 20, and then submitting the product to
the procedure of Example 21, cis-1-ED-3-(acetylthio)-
2-methylpropanoyl-4-iodo-L-proline, and cis 4-iodo-
l-[D-3-mercapto-2-methylpropanoyl]-L-proline are
obtained.
Example 28
cis-4-Fluoro-1-~3-mercapto-2-trifluoromethylpropanoyl)-
L-proline
By substituting 3-acetylthio-2-trifluoromethyl-
propanoic acid chloride for the 3-acetylthio-2-methyl-
propanoic acid chloride in the procedure of Example
20 and then submitting the product to the procedure
of Example 21, cis-1-13-(acetylthio)-2-trifluoro-
methylpropanoyl]-4-fluoro-L-proline and cis-4-fluoro-1-
(3-mercapto-2-trifluoromethylpropanoyl)-L-proline,
respectively, are obtained.
Example 29
cis-3-Fluoro-DL-proline, hydrobromide
By substituting ~-carbobenzyloxy-3-hydroxy-DL-
proline [J. ~m. Chem. Soc. 85, 2824 (1963)1 for the
N-carbobenzyloxy-4-hydroxy-L-proline in the procedure
of Example 19, cis-3-fluoro-DL-proline hydrobromide
is obtained,
~ Example 30
; 25 cis-3-Fluoro-l-(D-3-mercapto-2-methylpropanoyl-DL-proline
By substituting cis-3-fluoro-DL-proline hydro-
bromide for the cis-4-fluoro-DL-proline in the pro-
cedure of Example 20 and then submitting the product
to the procedure of Example 21, cis-1-~D-3-(acetylthio)-
2-methylpropanoyll-3-fluoro-DL-proline and cis-3-fluoro-
l-(D-3-mercapto-2-methylpropanoyl)-DL-proline are
obtained.
~1~ 3
30 ~IA162a-b
Examplc 31
cis-3-Chloro-l-(D-3-mercapto-2-mcthylpropanoyl-
L-proline
By substituting cis-3-chloro-L-proline [obtained
from 3-hydroxyproline by the procedure described in
Aust. J. Chem. _, 1493 (1967)] for the cis-4-
fluoro-L-proline hydrobromide in the procedure of
Example 20 and then submitting the product to the
procedure of Example 21, cis-1-[D-3-(acetylthio)-2-
methylpropanoyl-3-chloro-L-proline, and cis-3-ahloro-
l-(D 3-mercapto-2-methylpropanoyl)-L-proline are
obtained.
Example 32
4,4-Dichloro-l-(D-3-mercapto-2-methylpropanoyl)-
L-proline
By substituting 4,4-dichloro-L-proline [prepared
from 4-keto-L-proline diketopiperazine and phos-
phorus pentachloride by the procedure described in
J. Med. Chem. 20, 1176 (1977)] for the cis-4-fluoro-
L-proline hydrobromide in the procedure of Example 20,
and then submitting the product to the procedure of
Example 21, 1-[D-3-(acetylthio)-2-methylpropanoyl]-4,
4-dichloro-L-proline and 4,4-dichloro-1-(D-3-mercapto-
2-methylpropanoyl)-L-proline are obtained.
Example 33
1,1'-[Dithiobis-(2-D-methylpropanoyl)]-bis-[(cis-
4-fluoro)-L-pro_ine]
By substituting cis-4-fluoro-1-(D-3-mercapto-
2-methylpropanoyl)-L-proline for the 1-(3-mercapto-
2-trifluoromethylpropanoyl)-L-proline in the pro-
cedure of Example 9, 1,1'-[dithiobis-(2-D-methyl-
propanoyl)]-bis-[(cis-4-fluoro)-L-proline] is
obtained.
-
3 ~2~
31 ~-IA162a-b
Example 34
4,4-Difl _ro-1-(3-merca~>tol_tanoyl)-1,-Lroline
By substituting 3-acetylthiobutanoic acid
chloride for the 3-acetylthio-2-trifluoromethyl-
propanoic acid chloride in the procedure of
Example 11 and then submitting the product to
the procedure of Example 12, 1-(3-acetylthio-
butanoyl)-4,4-difluoro-L-proline and 4,4-difluoro-
1-(3-mercaptobutanoyl)-L-proline are obtained.
Example 35
1-(3-Propanoylthio-2-trifluoromethylpropanoyl)-
L-proline
By substituting thiopropanoic acid for the
thioacetic acid in the procedure of Example 1
and then submitting the product to the procedures
of Examples 2 and 3, 3-propanoylthio-2-trifluoro-
methylpropanoic acid, 1-(3-propanoylthio-2-
trifluoromethylpropanoyl)-L-proline tert butyl
ester and l-(3-propanoylthio-2-trifluoromethyl-
propanoyl)-L-proline, respectively, are obtained.
Example 36
3-(4-Methoxybenzyl)thio-2-trifluoromethylpropanoic
acid
A neat mixture of l-trifluoromethylacrylic
acid (3.9 g.) and 4-methoxybenzylthiol (4.3 g.) is
stirred at 100-110 for one hour. The mixture is
allowed to cool to room temperature and the solid
is recrystallized from cyclohexane, m.p. 72-74 .
Example 37
1-~3-(4-Methoxybenzyl)thio-2-tr
oyl~-L-proline tert-butyl ester
-
A solution of 3-(4-methoxybenzyl)thio-2-trifluoro-
methylpropanoic acid (6.5 g.) and proline tert-
butyl ester (3.76 g.) in dichloromethane (500 ml.)
~ ~ .
1~2~7%3 ~IA162a-b
is stirred at 0 and treated with dicyclohexylcarbodi-
imide (4.53 g.). After 30 ~linutes at 0 and over-
night at room temperature, the mixture is filtered
and the filtrate is washed neutral. The organic
layer is dried and concentrated to dryness in vacuo.
The TLC [silica gel methylene chloride/ethyl3 acetate
(95:5)] shows two major spots Rf 0.46 and 0.51
corresponding to the two diastereoisomers.
Example 38
1-(3-Mercapto-2-trifluoromethylpropanoyl)-L-proline
A solution of 1-[3-(4-methoxybenzyl)thio-2-
trifluoromethylpropanoyl]-L-proline tert-butyl ester
(4.47 g.) obtained in Example 37 and anisole (10 ml.)
is cooled to 0 and trifluoroacetic acid (100 ml.)
is added, followed by mercuric acetate (3.18 g.).
The bath is removed and the mixture is stirred at room
temperature for one hour. The mixture is concentrated
to dryness in vacuo and the residue is triturated with
ether-hexane. The insoluble material is suspended in
water and hydrogen sulfide is bubbled through for 10
minutes. The precipitate is removed by filtration and
the filtrate is freeze dried to give the product,
~-(3-mercapto-2-trifluoromethylpropanoyl)-L-proline
as an amorphous solid. Rf 0.29 - 0.31 (silica gel-
benzene:acetic acid 7:1).
Example 393-Acetylthio-2-chloropropanoic acid chloride
By substituting 2-ahloroacrylic acid for the
2-trifluoromethylacrylic acid in the procedure of
Example 1 and then allowing the product to react with
thionyl chloride, 3-acetylthio-2-chloropropanoic acid
and 3-acetylthio-2-chloropropanoic acid chloride are
obtained.
,,,
1~4723
33 ElAl62a-b
Example 40
D-3-Acetylthio-2-methylpropanoic acid chloride
A suspension of l-(D-3-mercapto-2-methylpropan-
oyl)-L-proline, (150 g. 690 mmoles), in 1274 ml.
of water and 426 ml. of concentrated hydrochloric
acid (5.526 moles) is refluxed under nitrogen
with stirring for 8 hours. The resulting solution is
kept at room temperature overnight and then
extracted with 400 ml. of chloroform (10 x). The
combined chloroform extracts are dried over
magnesium sulfate under nitrogen and then evaporated.
To the residue, 81.2 g. is added acetic anhydride,
(176 ml., 1.809 mole), and pyridine, 180 ml., and
the mixture is kept at room temperature for 20 hours.
The mixture is then evaporated and the oily residue
is dissolved in 1000 ml. of ethyl acetate and the
solution is washed in sequence with 200 ml.
5% hydrochloric acid-saturated sodium chloride
(washing pH 2), 200 ml. of saturated sodium
chloride solution (2 times, second washing pH 7)
and then stripped of the solvent. To the clear
oily residue, [96.9 g., 86.5~, had [a]D = -61.8
(CE~C13)]is added freshly distilled thionyl chloride,
(83 ml., 1.173 mole) and the resulting solution is
stirred at room temperature with evolution of gas
for 18 hours. The excess thionyl chloride is
evaporated under vacuum and a 50 bath and the
3~ residue is distilled at reduced pressure to obtain
56.9 g. of D-3-acetylthio-2-methylpropanoic acid
chloride, b.p. 40-4 (0.17 -0.2 mm Hg.)
[ ]25 -42.5 (c 2; methanol).
~ .
~.~.~7~ A 1 ~) 2 ~ - ~
34
Example 41
3-Acetylthio-2-bromopropanoic acid chloride
By substituting 2-bromoacrylic acid for the
2-trifluoromethylacrylic acid in the procedure of
Example 1 and then allowing the product to react with
thionyl chloride, 3-acetylthio-2-bromopropanoic
acid and 3-acetylthio-2-bromopropanoic acid chloride
are obtained.
~xample 42
Trans-1-[D-3-(acetylthio)-2-methyl-1-oxopropyl]-4-
fluoro-L-proline
A) Trans-l-carbobenzyloxy-4-fluoro-L-proline
A solution of 6.2 grams of trans-l-carbobenzyloxy-
4-fluoro-L-proline, methyl ester in 50 ml of methanol
is treated dropwise a~ 0-5, with 11.5 ml of 2N
sodium hydroxide solution, and after 1 hour at 0,
allowed to warm to room temperature overnight. mhe
reaction mixture is concentrated under reduced pressure
to about one-half its original volume and is then
diluted with 100 ml of water. The aqueous reaction
mixture is extracted with ether and the ether extracts
discarded. The aqueous solution is acidified, with
cooling, with dilute hydrochloric acid to p~ 2 and
then extracted with ethyl acetate (4 x 50 ml). The
combined ethyl acetate extracts are dried over anhydrous
magnesium sulfatel and then concentrated under reduced
pressure to yield the desired product. It is purified
by conversion to the cyclohexylamine salt, mp. 194-
196, 25 ~44 (c=l~ in methanol).
HAl 62a-b
The free acid is obtained by
suspension of cyclohexylamine salt in 25 ml of ethyl
acetate with 22 ml of N hydrochloric acid and extract-
ing the aqueous layer with ~ x 35 ml of ethyl acetate.
The combined ethyl acetate extracts are dried over
anhydrous magnesium sulfate and the solvent concen-
trated under reduced pressure to yield the desired
trans -l-carbobenzyloxy-4-fluoro-L proline.
B) Trans-4-fluoro-L-proline, hydrobromide
A mixture of 3 grams of trans-1-carbobenzyloxy-4-
fluoro-L-proline and 15 ml of hydrogen bromide in
acetic acid (30-32%) is stirred for 1 hour, and
then 150 ml of anhydrous ether is added. The solvent
is decanted from the precipitate that is then tri-
turated with fresh ether and finally with methyl ethyl
ketone. The trans-4-fluoro-L-proline hydrobromide
melts at 162-164 (dec), [al25 -30 (c=1% in methanol).
C) Trans-l-[D-3-(acetylthio)-2-methyl-1-oxopropyl]-
4-fluoro-L-proline
To a stirred solution of 1.9 grams of trans 4-
fluoro-L-proline hydrobromide in 25 ml of cold water
there is added 1 gram of sodium carbonate to adjust
pH to 8.2. Then with continued cooling (5) and
stirring there is added dropwise 1.8 grams of D-3-
acetylthio-2-methylpropionyl chloride in 2.5 ml of
ether, while maintaining the pH at about 8.2-8.3 by
the dropwise addition of a 25% aqueous sodium carbonate
solution. The stirring and cooling is continued for
one hour after the addition is completed. The reaction
mixture is extracted with ethyl acetate (2 x 25 ml)
and the extracts discarded. To the aqueous layer is
added 50 ml of ethyl acetate and with stirring and
, ~ HA162a-b
cooling, concentrated hydrochloric acid is added
dropwise to a pH of 2Ø The a~ueous layer is satu-
rated with sodium chloride and the ethyl acetate layer
separated. The aqueous layer is extracted with additional
ethyl acetate (3 x 25 ml), the combined ethyl acetate
extracts dried over anhydrous magnesium sulfate and
concentrated under reduced pressure to yield the
desired product. The dicyclohexylamine salt is
prepared by dissolving the product in 25 ml of ethyl
acetate and adding a solution of 1.8 gram of dicyclo-
hexylamine in 35 ml of ethyl acetate. The precipitated
salt is filtered and recrystallized from isopropanol
to yield the dicyclohexylamine salt of trans l-[D-3-
(acetylthio)-2-methyl-1-oxopropyl]-4-fluoro-L-proline;
15 mp. 209-211, E~]D5 -85 (c=1% methanol).
The free acid is recovered by dissolving the
dicyclohexylamine salt in 5% aqueous potassium acid
sulfate and extraction with ethyl acetate. The ethyl
acetate solution is dried over anhydrous magnesium
sulfate and concentrated under reduced pressure to
yield the desired trans l-[D-3-(acetylthio)-2-methyl-
l-oxopropyl]-4-fluoro-L-proline.
Example 43
trans-4-fluoro-1-(D-3-mercapto-2-methyl-1-oxopropyl)-
L-proline
Argon is passed through a cold solution of 4.2 ml
of concentrated ammonium hydroxide in 16 ml of water.
To this solution there is added, with stirring in an
atmosphere of argon, 1.8 grams of trans-1-[D-3-(acetyl-
thio)-2-methyl-1-oxopropyl]4-fluoro-L-proline. The
reaction mixture is stirred for an additional two
hours and is then extracted with ethyl acetate which is
~iA162a-b
37
discarded. The aqueous layer is stirred, 30 ml of
ethyl acetate added, and the aqueous layer acidified
with concentrated hydrochloric acid. The aqueous layer
is saturated with sodium chloride and the ethyl
acetate layer separated. The aqueous layer is extracted
with ethyl acetate (3 x 30 ml). The combined
ethyl acetate extracts are dried over anhydrous
magnesium sulfate and concentrated under reduced
pressure to yield the desired trans-4-fluoro-1-[D-
3-mercapto-2-methyl-1-oxopropyl)-L-proline; [a]26
-112(c=1% in methanol).
Example 44
l-[D-3-(acetylthio)-2-methyl-1-oxopropyl]-4,4-difluoro-
L-proline
A) l-carbobenzyloxy-4,4-difluoro-L-proline, methyl
ester
To a cooled stirred solution of 3.3 grams of 1-
carbobenzyloxy-4-keto-L-proline, methyl ester in 80
ml of methylene dichloride there is added dropwise
3.3 ml diethylaminosulfurtrifluorids. The reaction
mixture is allowed to remain overnight at room
temperature. About 100 grams of crushed ice is added
with stirring and the reaction mixture stirred for
45 minutes. The organic layer is separated and the
aqueous layer extracted with methylene chloride
(2 x 40 ml). The combined extracts are dried over
anhydrous magnesium sulfate and then concentrated
under reduced pressure to yield the desired l-carbo-
benzyloxy-4,4-difluoro-L-proline, methyl ester.
'`
ilZ~Z3 ~A162a-b
38
B) l-carbobenzyloxy-4,4-difluoro-L-proline
A solution of 5.6 grams of 1-carbobenzyloxy-4,4-
difluoro-L-proline, methyl ester in 50 ml of methanol
is treated dropwise with 11.5 ml of 2 .I sodium hydrox-
ide solution at 0-5. The reaction mixture is left
at 0 for 1 hour and is then allowed to warm to room
temperature overnight. The reaction mixture i5 con-
centrated under reduced pressure to about one-half its
original volume and is then diluted with 100 ml of
water. The aqueous reaction mixture is extracted
with ether and the ether extracts discarded. The
aqueous solution is acidified with cooling with dilute
hydrochloric acid to pll 2 and is then extracted with
ethyl acetate (3 x 50 ml). The ethyl acetate ex-
tracts are combined and washed with saturated sodium
chloride solution, dried over anhydrous magnesium
sulfate and concentrated to yield the desired
product, l-carbobenzyloxy-4,4-difluoro-L-proline.
It is purified by conversion to the cyclohexylamine
salt. mp. 180-185L~]D6 = -24 (c=1% in ethanol).
The free acid is obtained by treating an
aqueous solution of the cyclohexylamine salt with
hydrochloric acid and extracting the mixture with ethyl
acetate (4 x 30 ml). The ethyl acetate extracts are
dried over anhydrous magnesium sulfate and concentrated
under reduced pressure to yield the desired l-carbo-
benzyloxy-4,4-difluoro-L-proline.
C) 4,4-Difluoro~L-proline, hydrobromide
A mixture of 2.4 grams of 1-carbobenzyloxy-4,4-
difluoro-L-proline and 12 ml of hydrogen bromlde in
acetic acid (30-32%) is stirred for 30 minutes at room
~ . ,
~ 23 HA162a-b
39
temperature and then 300 ml of anhydrous ethe~ is
added. The mixture is cooled and the precipitated
solid is filtered and dried under reduced pressure.
The desired 4,4--difluoro-L-proline, hydrobromide
melts at 163-165 (dec); [~D = -14 (c=l~ in
methanol).
D) l-LD-3-(acetylthio)-2-methyl-1-oxopropyl]-4,4-
difluoro-L-proline
To a stirred solution of 2.7 grams of 4,4-difluoro-
L-proline, hydrobromide in 30 ml of water, cooled to
5, there is added solid carbonate to adjust the pH
to 8.4. Then with continued cooling and stirring
there is added dropwise 2.4 grams of D-3-acetylthio-
2-methylpropionyl chloride in 3 ml of anhydrous ether,
while maintaining the pII of the solution at 8.1-8.3
by the addition of a 25% aqueous sodium carbonate
solution: The stirring and cooling is continued for
one hour after the addition is completed. The reaction
mixture is extracted with ethyl acetate (2 x 25 ml)
and the extracts discarded. To the aqueous layer is
added 50 ml of ethyl acetate and, with stirring and
cooling, there is added dropwise concentrated hydro-
chloric acid to a pH of 2Ø The aqueous layer is
saturated with sodium chloride and the ethyl acetate
layer separated. The aqueous layer is extracted with
ethyl acetate (3 x 25 ml) and the combined ethyl acetate
extracts dried over anhydrous magnesium sulfate and
concentrated under reduced pressure to yield the
desired product. The dicyclohexylamine salt is
prepared by dissolving the product in 40 ml of ethyl
acetate and adding a solution of 2.3 grams of di-
cyclohexylamine in 5 ml of ethyl acetate. The pre-
:
.
l~X~ ~(Z3 ~1~162a-b
cipitated salt is filtered and recrystallized from
ethanol. The dicyclohexylamine salt of l-[D-3-
(acetylthio)-2-methyl-1-oxopropyl]4,4-difluoro-L-
proline melts at ~25-227; L~]D = -70 (c=0.5% in
methanol).
The free acid is recovered by dissolving the
dicyclohexylamine salt in 5% aqueous potassium acid
sulfate and extraction with ethyl acetate. The
ethyl acetate solution is dried over anhydrous
magnesium sulfate and concentrated under reduced
pressure to yield the desired l-[D-3-(acetylthio)-2-
methyl-1-oxopropyl]-4,4-difluoro-L-proline.
Example 45
4,4-Difluoro-l-(D-3-mercapto-2-metnyl-1-oxopropyl)-
L-proline
Argon is passed through a cold solution of 4.6
ml of concentrated ammonium hydroxide in 11 ml of water.
To this solution there is added, with stirring in an
atmosphere of argon 2.1 grams of 1-[D-3-(acetylthio)-2-
methyl-1-oxopropyl]-4,4-difluoro-L-proline. The
reaction mixture is stirred an additional two hours and
is then extracted with ethyl acetate, which is discarded.
The aqueous layer is stirred, 30 ml of ethyl acetate is
added and the aqueous layer acidified with concentrated
hydrochloric acid. The aqueous layer is saturated
with sodium chloride and the ethyl acetate layer
separated. The aqueous layer is extracted with ethyl
acetate (3 x 25 ml). The combined ethyl acetate
extracts are dried over anhydrous magnesium sulfate
and concentrated under reduced pressure to yield the
desired 4,4-difluoro-1-(D-3-mercapto-2-methyl-1-
oxopropyl)-L-proline.
~z~3 HA162a-b
xample 46
l-[D-3-(acetylthio)-2-methyl-1-oxopropyl]-5-fluoro-
2-pipecolic acid
A~ l-Carbobenzyloxy-5-hydroxy-L-pipecolic acid,
methyl ester
A solution of 5 grams of 1-carbobenzyloxy-5-
hydroxy-L-pipecolic acid in 60 ml of dioxane is
treated with an ethereal solution of diazomethane
portionwise, uniil the yellow color persists. The
temperature is maintained at about 5 during the
addition. The excess diazomethane is destroyed with
glacial acetie acid and the resulting solution dried
over anhydrous magnesium sulfate. The solution is
concentrated under reduced pressure to yield the
desired 1-carbobenzyloxy-5-hydroxy-L-pipecolic acid,
methyl ester as a pale yellow viseous oil.
B) l-Carbobenzyloxy-5-tosyloxy-L-pipecolie aeid,
methyl ester
To a stirred solution of 5.7 grams of l-earbo-
benzyloxy-5-hydroxy-L-pipeeolic acid, methyl ester in
12 ml of pyridine, there is added dropwise at 5 to 8
a solution of 4 grams of tosyl chloride in 6 ml of
pyridine. The reaction mixture is kept at 5 for 72
hours and is then treated, with cooling, with 200 ml
of ice-cold 2-N hydrochloric acid. The precipitate is
dissolved in chloroform and the aqueous solution ex-
traeted with additional chloroform (3 x 75 ml). The
combined chloroform solutions are dried over anhydrous
magnesium sulfate and coneentrated under reduced pressure
to yield the desired 1-earbobenzyloxy-5-tosyloxy-L-
pipeeolic aeid, methyl ester, melting at 74-76, after
erystallization from isopropanol, La] 26 = _5, c=1%
~;Z4~23
HA162a-b
42
in methanol, [(~26= -llC~, c=l'~ in chloroform.
C) l-Carbobenzyloxy-5-fluoro-L-pipecolic acid, methyl
ester
A stlrred suspension of 5.2 ~rams of l-carbo-
benzyloxy-5-tosyloxy-L-pipecolic acid, methyl ester in
50 ml of diethylene ~lycol is treated with 5.2 grams
of anhydrous potassium fluoride and the mixture
heated at 80, with stirring for 14 hours. The cooled
solution is diluted with 50 ml of water and extracted
with ethyl acetate (3 x 100 ml). The ethyl acetate
extracts are combined, washed with a saturated sodium
chloride solution and dried over anhydrous maynesium
sulfate. The solvent is removed under reduced pressure
to yield the desired l-carbobenzyloxy-5-fluoro-L-
pipecolic acid, methyl ester as a yellow oil.D) l-Carbobenzyloxy-5-fluoro-L-pipecolic acid
To a cooled (0) solution of 4.6 grams of 1-
carbobenzyloxy-5-fluoro-L-pipecolic acid, methyl ester
in 32 ml of methanol there is added 7.3 ml of 2N
sodium hydroxide solution. The reaction mixture is
; allowed to remain at 0-5 for one hour and at room
temperature overnight. The solution was concentrated
to about one-half its volume under reduced pressure and
diluted with 20 ml of water. The solution is extracted
with ether, which is discarded. The aqueous solution
is cooled, acidified with concentrated hydrochloric
acid and extracted with ethyl acetate (3 x 50 ml). The
combined ethyl acetate extracts are dried over anhydrous
magnesium sulfate and concentrated under reduced
pressure to yield the desired 1-carbobenzyloxy-5-fluoro-
L-pipecolic acid. It is purified by conversion to the
-
~7 2 3 HA162a-b
43
cyclohexylamine salt, which melts at 158-161 L~]D6 =
-11 (c=1% in methanol.
The free acid is obtained by treating an aqueous
solution of the salt with hydrochloric acid, extracting
the mixture with ethyl acetate (4 x 25 ml) and concen-
trating the dried extracts under reduced pressure.
E) 5-Fluoro-L-pipecolic acid hydrobromide
A mixture of 2.2 grams of 1-carbobenzyloxy-5-
fluoro-L-pipecolic acid and 12 ml of hydrogen bromide
10 in acetic acid (30-32%) is stirred for 30 minutes at
room temperature and then 300 ml of anhydrous ether is
added. The cooled mixture is filtered and the pre-
cipitated solid dried under reduced pressure to yield
5-fluoro-L-pipecolic acid hydrobromide.
F) l-[D-3-(acetylthio)-2-methyl-1-oxopropyl]-5-fluoro-
L-pipecolic acid
To a suspension of 5.1 grams of 5-fluoro-L-pipecolic
acid hydrobromide in 100 ml of dimethylacetonide there
is added 10 grams of i~ methylmorpholine. To this
mixture there is then added, slowly, with vigorous
stirring 5.4 grams of D-3-acetyl-2-methylpropionyl
chloride and the reaction mixture heated at 90 for
three hours. The cooled reaction mixture is filtered
and concentrated under reduced pressure. The residue
is treated with dilute hydrochloric acid and is ex-
tracted with ethyl acetate (3 x 150 ml). The ethyl
acetate extracts are dried and then concentrated under
reduced pressure to yield l-[D-3-(acetylthio)-2-methyl-
l-oxopropyl]-5-fluoro-L-pipecolic acid.
The acid is purified by conversion to the dicyclo-
hexylamine salt followed by crystalli3ation of the salt
from acetonitrile.
l~Z~723
HA162a-b
44
EYample 47
uoro-1-(D-3-mercapto-2-methyl-1-oxopropyl)-L-
pipecolic acid
~Jitrogen is bubbled through a solution (5) of
S 11 ml of concentrated ammonium hydroxide in 25 ml of
water for 30 minutes. To this solution there is added
1.6 grams of 1-[D-3-(acetylthio)-2-methyl-1-oxopropyl]-
5-fluoro-L-pipecolic acid and the mixture stirred Eor
15 minutes at 5 and then 4 hours at room temperature.
The solution is then cooled, acidified with concentrated
hydrochloric acid and extracted with ethyl acetate
(3 x 50 ml). The ethyl acetate extracts are dried over
anhydrous magnesium sulfate and concentrated under
reduced pressure to yield 5-fluoro-1-(D-3-mercapto-2-
S methyl-l-oxopropyl)-L-pipecolic acid.
Example 48
1-(3-Mercapto-2-trifluoromethylpropanoyl)-L-pipecolic
acid
By substituting L-pipecolic acid tert-butyl ester
for the L-proline tert-butyl ester in the procedure of
Example 2, and submitting the product to the pro-
cedures of Examples 3 and 4, 1-(3-mercapto-2-trifluoro-
methylpropanoyl-L-pipecolic acid is obtained.
Example 49
1-(2-Mercapto-3,3,3-trifluoropropanoyl)-L-pipecolic
acid
By substituting L-pipecolic acid or the L-
proline inthe procedure of Example 7, and then sub-
mitting the product to the procedure of Example 8,
1-(2-mercapto-3,3,3-trifluoropropanoyl)-L-pipecolic
acid is obtained.
7Z3
llA162a-b
Example 50
1-(3-Mercapto-2-trifluoromethylpropanoyl)-5,5-difluoro-
DL-pipecolic acid
By substituting 5,5-difluoro-DL-pipecolic
acid [obtained from 5-keto-DL-pipecolic acid by the
procedure described in J. Med. Chem. 20, 1176 (1977)]
for the 4,4-difluoro-L-proline in the procedure of
Example 11 and submitting the product to the
procedure of Example 12, 1-(3-mercapto-2-trifluoro-
methylpropanoyl)-5,5-difluoro-DL-pipecolic acid is
obtained.
Example 51
1,1'-[Dithiobis-(2-trifluorometh~1-3-propanoyl)~bis-
5,5-difluoro-DL-pipecolic acid
By substituting 1-(3-mercapto-2-trifluoro-
methylpropanoyl)-5,5-difluoro-DL-pipecolic acid for
the l-~3-mercapto-2-trifluoromethylpropanoyl)-L-
proline in the procedure of Example 9, l,l'-[dithio-
bis-(2-trifluoromethyl-3-propanoyl)]bis-5,5-difluoro-
DL-pipecolic acid is obtained.
Example 52
1-(3-Mercapto-4,4,4-trifluorobutanoyl)-L-pipecolic
acid
By substituting L-pipecolic acid tert.-butyl
ester for the L-proline tert.-butyl ester in the
procedure of Example 14, and then submitting the
product to the procedure of Example 15, 1-(3-mer-
capto-4,4,4-trifluorobutanoyl)-L-pipecolic acid
is obtained.
;
1~24723 HA162a-b
46
~xample 53
1-(3-Mercapto-2-trifluoromethylpropanoyl)-5,5-dichloro-
DL-pipecolic acid
By substituting 5,5-dichloro-DL-pipecolic acid
[prepared from 5-keto-DL-pipecolic acid and phos-
phorus pentachloride by a procedure similar to that
described in J. Med. Chem. 20, 1176 (1977)] for the
4,4-difluor~Lproline in the procedure of Example 11
and then submitting the product to the procedure of
Example 12, 1-(3-mercapto-2-trifluoromethylpropanoyl)-
5,5-dichloro-DL-pipecolic acid is obtained.
Example 54
1-(3-Mercapto-2-methylpropanoyl)-5,5-difluoro-DL-
pipecolic acid
By substituting 3-acetylthio-2-methylpropanoic
acid chloride for the 3-acetylthio-2-trifluoromethyl-
propanoic acid chloride in the procedure of Example
11 and then submitting the product to the procedure
of Example 12, 1-(3-mercapto-2-methylpropanoyl)-5,5-0 difluoro-DL-pipecolic acid is obtained.
Example 55
1-(3-Mercapto-2-methylpropanoyl)-5-fluoro-DL-pipecolic
acid
By substituting 3-acetylthio-2-methylpropanoic
acid chloride for the 3-acetylthio-2-trifluoromethyl-
propanoic acid chloride and 5-fluoro-DL-pipecolic
acid [prepared from 5-hydroxypipecolic acid by a
procedure similar to that descrbied in Biochemistry,
4, 2507 (1965)] for the 4,4-difluoro-L-proline in the
procedure of Example 11, and then submitting the
product to the procedure of Example 12, 1-(3-acetyl-
thio-2-methylpropanoyl)-5-fluoro-DL-pipecolic acid
1~472:~
HA162a-b
and l-(3-mercapto-2-methylpropanoyl)-5-fluoro-DL-
pipecolic acid are obtained.
Example 56
1-(3-Mercaptopropanoyl)-5-bromo-DL-pipecolic acid
Bysubstituting 3-acetylthiopropanoyl chloride
for the 3-acetylthio-2-trifluoromethylpropanoic
acid chloride and 5-bromo-DL-pipecolic acid [prepared
from 5-hydroxypipecolic acid by a procedure similar
to that described in Aust. J. Chem., 20, 1493 (1967)]
for 4,4-difluoro-L-proline in the procedure of
Example 11 and submitting the product to the procedure
of Example 12, 1-(3-acetylthiopropanoyl)-5-bromo-DL-
pipecolic acid and l-(3-mercaptopropanoyl)-5-bromo-
DL-pipecolic acid are obtained.
Example 57
1-(3-Acetylthio-2-trifluoromethylpropanoyl)-DL-pipe-
colic acid methyl ester
By substituting DL-pipecolic acid methyl ester
for the L-proline tert-butyl ester in the procedure
of Example 2, 1-(3-acetylthio-2-trifluoromethylpro-
panoyl)-DL-pipecolic acid methyl ester is obtained.
Example 58
1-(3-Mercapto-2-trifluoromethylpropanoyl-DL-
pipecolic acid methyl ester
By substituting DL-pipecolic acid methyl ester
for the L-proline tert-butyl ester and 3-mercapto-
2-trifluoromethyl propanoic acid for the 3-acetylthio-
2-methylpropanoic acid in the procedure of Example 2,
, . _
~247~3
ll~162a-b
48
1-(3-mercapto-2-trifluoromethylpropanoyl)-DL-
pipeeolie aeid methyl ester is obtained.
Example 59
1-(3-Propanoylthio-2-trifluoromethylpropanoyl)-5-
fluoro-DL-pipecolic acid
,
By substituting thiopropanoic aeid for the
thiolaeetie acid in the procedure of Example 1, and
then submitting the produet to the procedure of
Example 26, 1-(3-propanoylthio-2-trifluoromethylpro-
panoyl)-5-fluoro-DL-pipecolic acid is obtained.
Example 60
1-(3-Mereapto-2-methylpropanoyl)-5-fluoro-DL-
pipecolie aeid sodium salt
An aqueous solution of 1-(3-mercapto-2-methyl-
propanoyl)-5-fluoro-DL-pipecolic acid is mixed with an
equimolar amount of aqueous N-sodium hydroxide and the
solution is freeze dried.
Example 61
1-(3-Mereaptopropanoyl)-5,5-diehloro-DL-pipecolic acid
By substituting 3-acetylthiopropanoic aeid
ehloride for the 3-aeetylthio-2-trifluoromethylpro-
panoie aeid ehloride in the proeedure of Example 53,
1-(3-mercaptopropanoyl)-5,5-dichloro-DL-pipeeolie
aeid is obtained.
The racemic forms of the final products in
eaeh of the foregoing examples are produeed by util-
izing the DL-form of the starting amino acid instead
of the L-form.
Similarly, the D-form of the final products
in eaeh of the foregoing examples is produeed by
utilizing the D-form of the starting amino aeid
instead of the L-form.
~723
HA162a-b
49
~ xample 62
1000 tablets each containing 100 mg. of l-(D-
3-mercaptopropanoyl)-cis-4-fluoro-L-proline, are
produced from the following ingredients:
1-(3-mercaptopropanoyl)-cis-4
fluoro-L-proline 100 g.
Corn starch 50 g.
Gelatin 7,5 g.
Avicel (microcrystalline cellulose) 25 g.
Magnesium stearate 2.5 g.
The l-(D-3-mercaptopropanoyl)-cis-4-fluor~-
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
press to form 1000 tablets each containing 100 mg.
of active ingredient.
Example 63
1000 tablets each containing 200 mg. of 1-
[D-3-(acetylthio)-2-methylpropanoyl]-cis-4-fluoro-
L-proline are produced from the following ingredients:
1-[D-3-(acetylthio)-2-methylpro-
panoyl]-cis-4-fluoro-L-proline200 g.
Lactose 100 g.
Avicel 150 g.
Corn starch 50 g.
Magnesium stearate 5 g.
The l-[D-3-(acetylthio)-2-methylpropanoyl]-cis-
4-fluoro-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
containing 200 mg. of active ingredient. The tablets are
l~Z~7~23
HA162~b
coated with a solution of Methocel E 15 (methyl
cellulose) including as a color a lake containing
yellow #6~
Example 64
Two piece #l gelatin capsules each containing
250 mg. of 1-(3-mercapto-4,4,4-trifluorobutanoyl)-L-
proline are filled with a mixture of the following
ingredients:
1-(3-mercapto-4,4,4-trifluoro-
butanoyl-L-proline 250 mg.
Magnesium stearate 7 mg.
USP lactose 193 mg.
Example 65
An injectable solution is produced as follows:
cis-l-[D-3-(mercapto)-2-methyl-
propanoyl)]-cis-4-fluoro-L-
proline 500 g
Methyl paraben 5 g,
Propyl paraben 1 g.
Sodium chloride 25 g.
Water for injection qs. 5 1.
The active substance, preservatives and sodium
chloride are dissolved in 3 liters of water for
injection and then the volume is brought up to
5 liters. The solution is filtered through a
sterile filter and aseptically filled into pre-
sterilized vials which are then closed with
presterilized rubber closures. Each vial contains
5 ml. of solution in a concentration of 100 mg.
1124723 HA162a-b
of active ingredient per ml. of solution for
injection.
The products of each example can be
similarly formulated as in Examples 62 to 65.
`:
