Note: Descriptions are shown in the official language in which they were submitted.
Lo o
-- 1 --
PRALINE DERIVATIVES AND PROCESS FOR
PRODUCING THE SAME
The present invention relates to praline derivatives of
the formula (I):
SHEA
R-A-S-CH2CHCO-N (I)
COO
(wherein is an azalea group bonded to the Amman group of
amino acid and is selected from the group consisting of cycle-
propanecarbonyl, cyclohexanecarbonyl and adamantanecarbonyl
groups; A is Gleason, sarcosine or Damon acid residue
and has an ~-carbonyl group that forms a they'll ester bond with
a sulfur atom) and pharmaceutically acceptable salts thereof.
Compounds similar to these compounds represented by
formula (I), for example, those wherein R is a bouncily, acutely
or t-butyloxycarbonyl group and A is Lyman acid are
described in U.S. Patent Application 2,050,3sgA~ European
Patent Application (REP) Allah describes compounds wherein
R is a bouncily, acutely, t-butyloxycarbonyl, cyclopentane-
carbonyl group or the like, and A is Lyman acid. EN
Allah describes compounds wherein R is a bouncily group and
A is a D-phenylalanyl group. But there is no prior art refer-
once that specifically describes the compounds represented
by formula (I). Therefore, they are undocumented novel
compounds and are useful as pharmaceuticals as will be
described hereunder.
The amino acid residue represented by A in formula (I)
,.,
- 2 _ ~351~
is Gleason, sarcosine or Damon acid residue. Illustrative
Damon acids include neutral, acidic or basic amino acids,
or aliphatic, aromatic, heterocyclic or alicyclic amino acids
such as D-alanine, D-leucine, D-asparagine, D-methionine,
D-glutamin~, D-phenylalanine, D-tryptophan, D-ornithine,
D-phenylglycine, D-threonine, D-glutamic acid, D-arginine,
D-cysteine, D-aspartic acid D-histidine, D-isoleucine, D-
praline, D-lysine, D-serine, D-tyrosine, and D-valine. Fun-
tonal groups in these amino acts such as hydroxyl, Marquette,
amino and carboxyl groups may be substituted by lower alkyd,
bouncily and lower alkanoyl groups. Preferred examples of A
include Gleason, sarcosine, D-alanine, D-leucine, D-methionine,
D-glutamine, D-phenylalanine, D-tryptophan and D-phenylglycine.
Thy group SHEA in structural formula (I)- has an
-CH2CHCO-
asymmetric carbon atom, so that the group may be in a D-form,
L-form or Deform i.e. a mixture of D- and L-forms. Either
form is included in the scope of the present invention, and
D- and Deforms are preferred for their biological activity.
The praline residue -No in formula (I) may be in a
OH
D-form, L-form or a Deform and either form is included in
the scope of the present invention, L- and Deform being
preferred for their biological activity.
Illustrative pharmaceutically acceptable salts of the
praline derivative of formula (I) include salts with alkali
metals such as sodium and potassium, salts with alkaline
- 3 - ~235120
earth metals such as calcium and magnesium, and salts with
basic amino acids such as arginine and Lawson. Calcium salts
and Lawson salts are preferred.
The present invention also relates to a process for
producing the praline derivatives of formula (I) or pharmacy-
tidally acceptable salts thereof. The compounds of formula (It
are produced by the following process:
A compound of formula (II):
SHEA
¦ (II)
R-A'-S-CH2CHCOOH
(wherein A' is Gleason r sarcosine or a protected or unprotected
Damon acid residue; R has the same meaning as defined above)
or a reactive derivative thereof is reacted with a compound of
formula (III~:
HO
(III)
COORS
(wherein R' is a hydrogen atom or a carboxyl-protecting group)
or a reactive derivative thereof, any protecting group is
removed from the reaction product, and the product is option-
ally converted to a pharmaceutically acceptable salt.
If A in formula (I) has a free functional group that
should not enter into the reaction such as a Marquette, hydroxyl,
amino or carboxyl group, the compound of formula (II) means
I a derivative wherein such group may be protected.
Any functional group in A' that should not enter into
the reaction may be protected by those groups which are convent
tonally used in the art of peptize synthesis and which can be
_ 4 _ ~35~20
removed under relatively mild conditions. For example, a
Marquette group can be protected by an aralkyl group such as
tritely, bouncily or p-methoxybenzyl; a hydroxyl group can be
protected by a bouncily group; an amino group can be protected
5 by a t-butyloxycarbonyl group; and a carboxyl group can be
protected by a t-butyl group. These protecting groups can be
removed by treating with hydrogen fluoride, trifluoroacetic
acid or hydrogen chloride. Alternatively, a carboxyl group
is protected by a loweralkyl-substituted sill group, such as
trimethylsilyl group, which is then removed by treatment with
water. When R' in formula (III) is a carboxyl-protecting
group, it may be a t-butyl group or a loweralkyl-substituted
sill group and can be removed by treatment with hydrogen
fluoride, trifluoroacetic acid, hydrogen chloride or water.
The reactive derivative of the compound of formula IT
is such that the carboxyl group that enters into the reaction
is activated. The carboxyl group can be activated into any
of the forms commonly employed in the art of peptize synthesis
such as activated asides, acid halides, activated esters and
mixed acid androids. Among these forms, activated esters
with N-hydroxysuccinimide, mixed acid androids with carbonic
acid monstrous, and activated asides with carbonyldiimidazole
are preferred. Carbodiimides such as dicyclohexylcarbodiimide
may be used as a condensing agent to form an aside bond between
the carboxyl group and amino group.
The reactive derivative of the compound of formula
(III) is such that the amino group of said compound is activated.
The amino group can be activated by any of the methods that
. ,.
_ 5 _ ~35~
are conventionally used in the art OX peptize synthesis, for
example, the method of introducing a sill group such as
trimethylsilyl group, the "phosphazo method" using a phosphorus
compound such as phosphorus trichloride [Ann. Chum., 572 96
(1951)], the phosphorous acid ester method using a phosphorous
acid ester such as tetraethyl ester of pyrophosphorous acid,
or the "N-carboxyanhydride method" INCA method).
The reaction can be performed in an inert organic
solvent such as tetrahydrofuran, Dixon, dimethylformamide,
hexamethyl-phosphotriamide, chloroform, dichloromethane or
acetonitrile. The reaction is generally performed under
cooling or at room temperature (-50 to Z0C), preferably from
-30 to 10C. The reaction period varies with the reaction
temperature, the compounds to be reacted and the solvent, and
it is generally between 0.5 and 48 hours, preferably between
1 and 6 hours. -I
After the aside formation reaction, any protecting
group in the reaction product is removed by any of the methods
specified above for the respective protecting groups.
The end compound can be isolated from the reaction
mixture and purified by any conventional method, for example,
by various types of chromatography using silica gel r dextran
cross linked polymer and porous polymers such as styrenes
divinylbenzene or acrylic acid esters. A suitable developing
solvent can be selected from among chloroform, ethyl acetate,
methanol, ethanol, tetrahydrofuran, Bunsen, water and asset-
nitrite. Alternatively, the end compound may be obtained by
first isolating the reaction product in the form of an organic
, ....~
- 6 - ~35120
salt such as a dicyclohexylamine salt which is then treated
with an acid such as hydrochloric acid or potassium hydrogen
sulfate.
The compound of formula I) thus obtained has a carboxyl
group on the praline site, so it is capable of forming salts
with various basic materials if desired. Salts with forum-
ceutically acceptable basic materials are particularly import
lent. Such salts can be prepared by a conventional method,
i.e. treating said carboxyl group with an equimolar amount
of any of the bases listed above (e.g. alkali metals, alkaline
earth metals and basic amino acids.
The compound of formula (II) used as the starting
material in the process of the present invention can be pro-
pared easily by the following method:
A compound of formula (VI):
R-OH (VI)
(wherein R is the same as defined above) or a reactive derive-
live thereof in the carboxyl group is reacted with an amino
acid of formula (VII):
H2N-A"-COOR" (VII)
(wherein A" is an amino acid residue equivalent to A' minus
the group NH or COO; R" is a hydrogen atom or a carboxyl-
protecting group) or a reactive derivative thereof, followed
by removing R" if it is a protecting group, to form a compound
of formula (VIII):
R-NH-A"-COOH (VIII)
(wherein R and A" are the same as defined above), subsequently
the compound of (VIII) or a reactive derivative thereof is
,
- 7 - ~3~1~0
reacted with a compound of formula (IX):
SHEA
¦ (IX)
HS-C~2CHCOOR"'
(wherein R"' is a hydrogen atom or a carboxyl-protecting group),
followed by removing R"' if it is a protecting group.
Examples of the reactive derivative in the carboxyl
group of the compound of formula (VI) include those which are
commonly employed in the art of peptize synthesis, such as
activated asides, acid halides, activated esters, and mixed
acid androids.
If R" in the amino acid of formula (VII) is a protecting
group, advantageous examples include a t-butyl group (which
can be removed by hydrogen fluoride, trifluroacetic acid or
hydrogen chloride), a bouncily group (which can be removed by
catalytic reduction with palladium or the like), and lower
alkyd groups such as methyl and ethyl (which can be removed
by hydrolysis under alkaline conditions).
The reactive derivative of the amino acid of formula
(VII) is such that the amino group is activated, and such
derivative is produced by any of the activating methods that
are conventionally used in the art of peptize synthesis, such
as introducing a sill group (e.g. trimethylsilyl group), the
"phosphazo method", the phosphorous acid ester method, and
N-carboxyanhydride method.
A carbodiimide such as dicyclohexylcarbodiimide may be
used as a condensing agent to form an aside bond between the
compound of formula (VI) and the amino acid of formula (VII).
- 8 - SUE
The reaction can be performed in an inert organic solvent
such as tetrahydrofuran, Dixon, dimethylformamide, hexamethyl-
phosphotriamide, chloroform, dichloromethane or acetonitrile.
The reaction is generally performed under cooling or at room
5 temperature (-50 to 20C), preferably from -30 to Luke. The
reaction period varies with the reaction temperature, the
compounds to be reacted and the solvent, and it is generally
between 0.5 and 48 hours, preferably between 1 and 6 hours.
If R" in formula (VII) is a protecting group, it can be
removed from the reaction product by any of the conventional
methods described above.
The compound of formula (VIII) can be isolated from the
reaction mixture and purified by any conventional method, for
example, by recrystallization from ethyl acetate, Nixon,
acetone or water, or by various types of chromatography as are
described in connection with isolation and purification of the
compound of formula (I), or by decomposing an organic salt
of the reaction product with an acid.
the compound of formula (VIII) may be reacted with the
compound of formula (IX) by reacting the carboxyl group in
the former compound with the Marquette group in the latter
compound in the presence of a condensing agent (i.e. carbide-
immediacy such as dicyclohexylcarbodiimide). A reactive derive-
live of the compound ox formula (VIII) may be reacted with
the compound of formula tip). Examples of the reactive
derivative of the compound of formula (VIII) include activated
asides, acid halides, activated esters and mixed acid ashy-
drives. Activated asides with carbonyldiimidazole are
.
9- ~23~2~
preferred.
The carboxyl group in the compound of formula (IX) may
or may not be protected. Preferred protecting groups are
t-butyl and other groups which can be removed under acidic
conditions.
The they'll ester forming reaction is performed in an
inert organic solvent such as tetrahydrofuran, Dixon, dip -
methylformamide, hexamethylphosphotriamide, chloroform, dip
chloromethane and acetonitrile. The reaction is generally
performed under cooling or at room temperature (-50 to 20C),
preferably at between -30 and 10C when the compound of
formula (VIII) is used in the form of an activated aside or
acid halide, and at between -10 and 10C when said compound
is used in the form of an acid android. The reaction period
varies with the reaction temperature, the compounds to be
reacted and the solvent, and it is generally between OHS and
48 hours, preferably between 1 and 6 hours. After the they'll
ester forming reaction, R"' is removed from the reaction
product if it is a protecting group. If the protecting group
is a t-butyl group, it can be removed by a conventional method,
i.e. by reaction with hydrogen fluoride, trifluoroacetic acid
or hydrogen chloride.
The end compound can be isolated from the reaction
mixture and purified by any conventional method, such as
recrystallization from an organic solvent such as ethyl
acetate or Nixon, various types of chromatography as are
described in connection with isolation and purification of
the compound of formula I), or by decomposing an organic
,,,,:
3512~
- 10 --
salt of the reaction product with an acid.
nether process for producing the end compound of the
present invention comprises reacting a compound of formula
(IV):
ROY (IV)
(wherein R and A' are the same as define above) or a reactive
derivative thereof with a compound of formula (V):
SHEA
HS-CH2CHCO-N~ TV)
COORS
(wherein R' is the same as defined above), removing any
protecting group from the reaction product, and optionally
converting the product to a pharmaceutically acceptable salt.
If A in formula (I) has a free functional group that
should not enter into the reaction such as a Marquette,
hydroxyl, amino or earboxyl group, the compound of formula
(IV) means a derivative wherein such group may be protected.
Any functional group in A' that should not enter into
the reaction is protected by those groups which are eonven-
tonally used in the art of peptize synthesis and which can
be removed under relatively mild conditions For example, a
Marquette group can be protected by an aralkyl group such as
tritely, bouncily or p-methoxybenzyl group; a hydroxyl group can
be protected by a bouncily group; an amino group can be protected
by a t-butyloxycarbonyl group; and a carboxyl group can be
protected by a t-butyl group. These groups can be removed by
treatment with hydrogen fluoride or hydrogen chloride.
L;23S120
Alternatively, a carboxyl group is protected by a lower alkyd=
substituted sill group, such as trimethylsilyl group, which
is then removed by treatment with water. When R' in formula
(V) is a carboxyl-protecting group, it may be a t-butyl group
or a lower alkyl-substituted sill group and can be removed
by treatment with hydrogen fluoride, trifluoroacetic acid,
hydrogen chloride or water.
The reactive derivative of the compound of formula (IV)
is such that the carboxyl group that enters into the reaction
is activated. The carboxyl group can be activated into a
suitable form such as activated asides, acid halides, activated
esters or mixed acid androids. Activated asides with carbon
nyldiimidazole are preferred. Carbodiimides such as duskily-
By carbodiimide may be used as a condensing agent to form an
aside bond from the carboxyl group and Marquette group.
The reaction between the compound of formula (IV) or
its reactive derivative and the compound of formula (V) is
performed in an inert organic solvent such as tetrahydrofuran,
Dixon, dimethylformamide, hexamethylphosphotriamide, sheller-
form, dichloromethane or acetonitrile. The reaction is generally performed under cooling or at room temperature t-S0
to 20C), and preferably at between -30 and 10C when the
compound of formula (IV) is used in the form of an activated
aside or acid halide, and at between -10 and 10C when said
compound is used in the form of an acid android. The
reaction period varies with the reaction temperature, the
compounds to be reacted and the solvent, and it is generally
between 0.5 and 48 hours, preferably between 1 and 6 hours.
- 12 - ~3~1~0
After the they'll ester forming reaction, any protecting group
is removed from the reaction product by any of the methods
specified for the respective protecting groups.
The end compound can be isolated from the reaction
mixture and purified by any of the conventional methods
described above, such as various types of chromatography using
silica gel, dextran cross linked polymer and porous polymers
like styrene-divinylbenzene or acrylic acid esters. A suitable
developing solvent can be selected from among chloroform,
ethyl acetate, methanol, ethanol, tetrahydrofuran, Bunsen,
water and acetonitrile. Alternatively, the end compound may
be obtained by first isolating the reaction product in the
form of an organic salt such as dicyclohexylamine salt which
is then treated with an acid such as hydrochloric acid or
potassium hydrogen sulfate.
The end compounds of the present invention, namely the
praline derivative of formula (I) and pharmaceutically accept-
able salts thereof, prevent the production of angiotensin II
from angiotensin I by inhibiting the activity of angiotensin
converting enzyme. Therefore, they are useful for treating
hypertension due to angiotensin II and as an agent to treat
cardiac insufficiency.
The activity of some of the end compounds of the present
invention to inhibit the angiotensin converting enzyme was
measured.
(1) Method
An angiotensin converting enzyme was extracted from a
rabbit lung. A O.lllM boric acid-Na2CO3 buffer solution
- 1 3 - ~:3~20
(pi 8.3, 0.6 ml), 0.2 ml of O.lllM boric acidic buffer
solution pi 8.3) containing 25 my benzoylglycylhistidyl
Lawson (substrate) and 0.1 ml of O.lllM boric acid-Na2CO3
buffer solution (pi 8.3) containing 10 8 to 10 3 M of test
S compounds (13 end compounds of the present invention indicated
in the table below) were put in test tubes and preincubated
at 37C for 5 to 10 minutes. Then, 0.1 ml of a solution of
the enzyme (acetone powder) was added to each test tube and
each mixture was incubated at 37C for 30 minutes. The bouncily-
Gleason produced by the aid of the enzyme was extracted with ethyl acetate in the presence of hydrochloric acid and its
amount was determined by W absorption at 228 no. The enzyme
activity in the presence of the test compounds relative to
that in the absence of the test compounds (100) was determined.
The concentration of each test compound at which the relative
activity of the enzyme was 50% was referred to as the activity
of each test compound to inhibit the activity of the enzyme
and was indicated as an Is value.
(2) Results
14 51~
Test compound I50
Compound No. 1 1.6 x 10 7
" No. 2 4.8 x 10 7
" No. 3 1.3 x 10~7
" No. 4 4.0 x 10~7
" No. 5 1.8 x 10~
" No. 6 2.4 x 10 7
" No. 7 1.0 x 10~7
" No. 8 1.5 x 10~7
" No. 9 1.7 x 10 7
" No. 10 4.8 x 10~8
" No. 11 1.7 x 10~7
" No. 12 5.4 x 10-7
" No. 13 4.4 x 10~7
Compound No. 1 : N-[3-(N-cyclohexanecarbonyl-D-alanylthio)-
2~D-methylpropanoyl]-L-proline
No. 2 ; N~[3~(N~cyclopropanecarbonyl-D-alanylthio)-
2-D-methylpropanoyl]-L-proline
No. 3 ; N-[3-(N~cyclohexanecarbonylglycylthio)-2-
D-methylpropanoyl]~L~proline
No. 4 : N~[3~(N~cyclohexanecarbonyl~N-methylglycyl-
thio)-2~D-methylpropanoyl]-L-proline
No. 5 : N-[3-(N-cyclopropanecarbonylglycylthio) -2-
D~methylpropanoyl]~L-proline
to
No. 6 : N~[3~(N~adamantanecarbonylglycylthio) -2- D-
methylpropanoyl]~L~proline
- 15 - 1~35~20
Compound No. 7 : N-[3-(N-cyclohexanecarbonyl-D-phenylalanyl-
thio)-2-D-methylpropanoyl]-L-proline
No. 8 : N-[3-(N-cyclohexanecarbonyl-D-leucylthio)-
2-D-methylpropanoyl~-L-proline
No. 9 : N-[3-(N-cyclohexanecarbonyl-D-tryptophylthio~-
2-D-methylpropanoyl]-L-proline
No. 10 : N-[3-(N-cyclohexanecarbonyl-D-phenylglycyl- -
thio)-2-D-methylpropanoyl]-L-proline
No. 11 : N-[3-(N-cyclohexanecarbonyl-D-methionylthio)-
2-D-methylpropanoyl]-~-proline
No. 12 : N-[3-(N-cyclohexanecarbonyl-D-glutaminylthio~-
2-D-methylpropanoyl]-L-proline
c~c/a~c~7c~ne awaken/
A No. 13 : NUN ~-D-alanylthio)-2-
D-methylpropanoyl]-L-proline
The activity of the end compounds of the present invent
lion lasts longer than known compounds having a similar activity r
say, 3-mercapto-2-D-methylpropanoyl-L-proline (conventionally
named Captopril), so the desired control of blood pressure can
be attained by fewer daily administrations. Captopril and
other known compounds cause a sudden drop in blood pressure
in the initial period of administration and this may develop
into orthostatic hypotensive asthenia looniest, vol. 1, No. 8,
115, p. 557 (March 10, 1979)], but the end compounds of the
present invention have only a mild hypotensive effect in
the initial period of administration and have little chance
to develop into orthostatic hypotensive asthenia. Drugs such
as Captopril that have a free Marquette group cause various
- 16 -
side effects that are attributable to that Marquette group.
To name a few, disorder in the sense of taste, production of
albumin in urine, agranulocytosis and dermal diseases accom-
panted by fever have been reported in Lance, vol. 1, No. 8160,
p. 150 (January 19, 1980), swooper, vol. 2, No. 8186, p. 129
(July 19, 1980), and South African Medical Journal, vol. 58,
172 (1980). On the other hand, the they'll ester bond in the
end compounds of the present invention is insusceptible to
hydrolysis in viva and hence is little likely to produce a
Marquette group. Therefore, the end compounds of the present
invention have little chance to cause the above named side
effects attributable to the Marquette group.
The praline derivative of formula (I) and its pharmacy-
tidally acceptable salts may be formulated in compositions for
oral administration such as tablets, capsules, granules,
powders, syrups and elixirs, or in sterile solutions or
suspensions for parenteral administration. For this purpose,
pharmaceutical compositions can be prepared from one or more-
of the end of compounds of the present invention (as the active
ingredient) and pharmaceutically acceptable adjutants such as
excipients, carriers, binders, stabilizers and flavors. The
daily dose of the end compounds of the present invention for
adults is from 0.5 my to 2 g, preferably from about 1 to 500 my,
for oral administration, and from 0.1 to 600 my, preferably
25 from about 0.3 to 300 my, for parenteral administration.
The process for preparing the end compounds of the
present invention is now described by reference to the following
examples to which the invention is by no means limited.
- 17 - 123S12~
Example l: Preparation of N-substituted amino acids
(a) D-alanine (4.5 g) was dissolved in 230 ml of aqueous
lN-Na2CO3 under stirring. To the solution, 100 ml of twitter-
hydrofuran containing 9.0 g of cyclohexanecarbonylchloride was
added drops at 5 - 10C, at which temperature the mixture
was stirred for 30 minutes, then stirred at room temperature
for 1.5 hours. Thereafter, 2N-HCl was added to the reaction
mixture to adjust its pi to between l and 2. The reaction
mixture was extracted with ethyl acetate, and the organic
layer was washed with saturated Nail solution and dried over
magnesium sulfate. The filtrate was evaporated under vacuum
to obtain a crude compound. Recrystallization from ethyl
acetate/n-hexane gave 4.65 g of N-cyclohexanecarbonyl-D-
ala nine. Do = +26.6
(b) An ester of adamantanecarboxylic acid and N-hydroxy-
succinimide ~3.0 g) was dissolved in 30 ml of tetrahydrofuran.
To the solution, water (5 ml) containing 0.89 g of D-alanine
and 1.1 g of triethylamine was added and the mixture was
stirred at 5C overnight. After removal of tetrahydrofuran,
water was added to the residue, and 2N-HCl was further added
to the mixture to adjust its pi to between l and 2. The
mixture was subsequently treated as in (a) above to give
0.38 g of N-adamantanecarbonyl-D-alanine. Do = +11.6
(C=1.0 Mesh)
The compounds listed below were prepared by either of
the methods described in (a) and (b).
..-
- 18 - ~L23~;120
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- 20 - ~35~0
Example 2
(a)3-(N-Cyclohexanecarbonyl-D-alanylthio)-2-D-methHal--
propanolc acid
N-Cyclohexanecarbonyl-D-alanine (5.97 g) was dissolved
in dry tetrahydrofuran (100 ml). To the solution, carbonyl-
diimidazole ~5.84 g) was added at between -20 and -15C, and
the mixture was stirred at that temperature for one hour.
Thereafter, 3-mercapto-2-D-methylpropanoic acid (3.60 g) was
added, and the mixture was stirred at between -15 and -10C
for one hour, then at room temperature for another owe hour.
The mixture was evaporated under vacuum to remove the solvent.
To the residue, water (40 ml) was added, and 2N-HC1 was added
to the mixture to adjust its pi to between 1 and 2. The mix-
lure was extracted with ethyl acetate, and the organic layer
was washed with saturated Nail solution twice, and dried over
magnesium sulfate. The filtrate was evaporated under vacuum
to obtain a crude compound. Recrystallization from ethyl
acetate/n-hexane gave a colorless prismatic crystal of the
titled compound (7.50 g, 83%).
mop. 149 - 152C
Do = +46.4 (C=1.07, Mesh)
NOR (CD30D, I): 1.20 (OH, d), 1.35 (OH, d),
1.20 - 2.0 (llH, m), 2.40 - 2.80 (lo, m),
3.05 (OH, m), 4.50 (lo, m)
(b) 3-(N-Cyclohexanecarbonyl-D-phenylglycylthio)-2-D-
methylpropanoic acid
The procedure of (a) above was repeated using N-cyclo-
hexanecarbonyl-D-phenylglycine (2.61 g), car~onyldiimidazole
(1.95 go and 3-mercapto-2-D-methylpropanoic acid (1.20 g).
, .
- 21 - ~235120
A yellow oil of the titled compound was produced t2.07 g, 57~).
Do = -48.7 Clue Mesh)
NOR (CDC13, I): 1.24 (OH, d), 1.20 - 2.10 (llH, m),
2.40 - 2.80 (lo, m), 3.10 (OH, m), 5.75 (lo, d),
Jo
6.40 - 6.80 (lo, m), I (OH, S), 8.90 (lo, S)
(c) 3-(N-Cyclohexanecarbonyl-D-leucylthio)-2-D-methyl---
propanoic acid
The procedure of pa) was reseated using N-cyclohexane-
carbonyl-D-leucine (2.41 g), carbonyldiimidazole (1.95 g) and
3-mercapto-2-D-methylpropanoic acid (1.20 g). An oil of the
titled compound was produced (2.40 g, 70%).
Do = +12.2 (C=1.03, Mesh)
NOR (CDC13, I): 0.95 (OH, d), 1.28 (OH, d),
1.20 - 2.10 (llH, m), 2.40 - 2.80 (lo, m),
3.10 (OH, m), 4.70 (lo, m), 6.00 - 6.30 (lo, m),
9.20 (lo, S)
(d) 3-(N-Cyclohexanecarbonyl-D-glutaminylthio)-2-D-
methylpropanoic acid
The procedure of (a) above was repeated using N-cyclo-
hexanecarbonyl-D-glutamine (2.56 g), carbonyldiimidazole
(1.95 g) and 3-mercapto-2-D-methylpropanoic acid (1.20 g).
A 0.70 g sample of the titled compound was produced (20%).
mop. 146 - 149C
Do = +10.8 ~C=1.05, Mesh)
NOR (CD30D, I): 1.20 (OH, d), 1.20 - 2.10 (llH, m),
2.30 (OH, m), 2.40 - 2.80 (lo, my, 3.05 (OH, m),
4.50 (lo, m)
(e) 3-(N-Cyclopropanecarbonyl-glycylthio)-2-D-methyl-
propanoic acid
it
- 22 - SUE
The procedure of (a) above was repeated using N-cyclo-
propanecarbonylglycine (0.78 g), carbonyldiimidazole (1.06 g)
and 3-mercapto-2-D-methylpropanoic acid (0.66 g). An oil of
the titled compound was produced (0.70 g, 52~).
[rid = -33.8 (C=1.01, Mesh)
NOR (CDC13, I): 0.70 - 1.20 (OH, m), 1.25 (OH, d),
1.30 - 1.80 (lo, m), 2.40 - 2.80 (lo, m), 3.14
I m), 4.20 (OH, d), 7.30 (lo, S)
(f) 3-(N-Adamantanecarbonyl-glycylthio)-2-D-methylproppanic
acid
The procedure of (a) above was repeated using N-
adamantanecarbonylglycine (2.38 g), carbonyldiimidazole (1.95 g)
and 3-mercapto-2-D-methylpropanoic acid (1.20 g). A 1.08 g
sample of the titled compound was produced (32~).
mop. 132C (doe.)
Do = -8.3 (C=1.01, MOE)
NOR (CD30D, I): 1.25 (OH, d), 1.65 - 2.30 (15H, m),
2.40 - 2.80 (lo, m), 3.14 (OH, m), 4.06 (OH, d)
(g) 3-(N-Cyclohexanecarbonyl-D-phenylalanylthio)-2-D-
methylpropanoic acid
The procedure of (a) above was repeated using N-cyclo-
hexanecarbonyl-D-phenylalanine ~1.37 g), carbonyldiimidazole
(1.0 g) and 3-mercapto-2-D-methylpropanoic acid (0.60 g).
An oil of the titled compound was produced (1.5 g, 79%).
[ED = +13-9 (C=1.02, Mesh)
NOR (CDC13, I): 1.25 (OH, d), 1.20 - 2.0 (lo, m),
2.1 - 3.0 (OH, m), 3.0 - 3.4 (OH, m), 4.95 (lo, t),
6.19 (lo, do, 7.24 (OH, S), 10.12 (lo, S),
- 23 - ~3512~
(h) 3-(N-Cyclohexanecarbonyl-D-methionylthio)-2-D-
methylpropanoic acid
The procedure of (a) was repeater using N-cyclohexane-
carbonyl-D-methionine (0.325 g), car~onyldiimidazole (0.25 g)
and 3-mercapto-2-D-methylpropanoic acid (0.15 g). An oil of
the titled compound was produced (0.29 g, 64~).
Do = ~7-9 (C=1.0, Mesh)
NOR (CDC13, I): 1.26 (OH, do, 1.2 - 2.0 (lo, m),
2.09 (OH, S), 2.0 - 3.2 (OH, m), 4.5 - 5.0 (lo, my,
6.62 (lo, d), 10.07 (lo, S)
(i) 3-(N-Cyclohexanecarbonyl-D-tryptophylthio)-2-D-
methylpropanoic acid
The procedure of (a) above was repeated using N-cyclo-
hexanecarbonyl-D-tryptophan (0.157 g), carbonyldiimidazole
(0.1 g) and 3 mercapto-2-D-methylpropanoic acid (0.06 g).
A gummy sample of the titled compound was produced (0.17 g, 82%).
Do = -7.1 (C=1.0, Mesh)
NOR (CDC13, I): 1.26 (OH, d), 1.2 - 2.4 (llH, m),
2.5 - 2.9 (lo, m), 3.0 - 3.3 (OH, m), 3.35 (OH, d),
4.87 (lo, t), 6.4 - 6.9 (OH, broad S), 6.9 - 7.8
(OH, m), 10.5 (lo, S)
Example 3
(a) N-[3-(N-Cyclohexanecarbonyl-D-alanylthio)-2-D-
methylpropanoyl]-L-proline
3-(N-Cyclohexanecarbonyl-D-alanylthio)-2-D-methyl---
propanoic acid (1.51 g) was dissolved in dry tetrahydrofuran
(40 ml). To the solution, triethylamine (0.61 g) and ethyl
chloroform ate (0.65 g) were added at -5C under stirring.
Five minutes later, a solution having L-proline (0.58 g) and
I.
- 24 _ ~23 So O
triethylamine (0.61 g) dissolved in water (5 ml) was added,
and the mixture was stirred at 0C for one hour, then at room
temperature for 30 minutes. The mixture was evaporated under
vacuum to remove the solvent. After adding water to the
residue, 2N-HCl was added to the mixture to adjust its pi to
between 1 and 2. The reaction mixture was extracted with
ethyl acetate, and the organic layer was washed with saturated -
Nail solution twice, and dried over magnesium sulfate. The
filtrate was concentrated under vacuum to remove ethyl acetate,
and the residue was subjected to chromatography on silica gel
using a mixture of chloroform and methanol (100;1 to 100:2)
as an eluant. Fractions containing the end compound were
collected and evaporated under vacuum to give a gummy sample
of the titled compound (0.3 go.
(b) The same compound could be produced by the following
method.
3-(N-Cyclohexanecarbonyl-D-alanylthio)-2-D-meth~l---
propanoic acid (6.03 g) and N-hydroxysuccinimide (2.3 g) were
dissolved in dry tetrahydrofuran (50 ml). To the solution,
dicyclohexylcarbodiimide (4.3 g) was added at between 0 and
5C, and the mixture was stirred overnight at that temperature.
After the reaction, the precipitate was filtered off and the
insoluble matter was washed with a small amount of twitter-
hydrofuran. The filtrate and the washings were combined and
CC~ f7C e r7z~ra~
cvapor~tc~ under vacuum. To the residue, ethyl acetate was added, and the mixture was filtered. The ethyl acetate soul-
lion was washed with 0.5N Hal, water, aqueous Nikko and
saturated Nail solution in the order mentioned. The solution
~2~5~20
- 25 -
was dried over magnesium sulfate, evaporated in vacuum, and
the residue solidified upon addition of a mixture of ethyl
acetate and hexane ~1:10). The yield of the solid product
was 6.90 g (87%).
mop. 113 - 116C
Do = +14.2 (C=1.05, Mesh)
NOR (CDC13, I): 1.38 (OH, d), 1.20 - 2.20 (llH, m),
2.82 (OH, S), 2.8 - 3.30 (OH, m), 4.75 (lo, m),
6.30 (lo, broad d)
The activated ester (3.98 g) was dissolved in twitter-
hydrofuran (40 ml). To the solution, water (5 ml) having
L-proline (1.15 g) dissolved therein and N-ethylmorpholine
(1.26 ml) were added, and the mixture was stirred overnight.
The mixture was evaporated under vacuum to remove the solvents,
and water was added to the residue. To the mixture, 2N-HCl
was added to adjust its pi to between 1 and 2. The reaction
mixture was extracted with ethyl acetate, and the organic
layer was washed with saturated Nail solution and dried over
magnesium sulfate. The filtrate was evaporated under vacuum.
The residue was subjected to column chromatography on silica gel
using a mixture of chloroform and methanol (100:1 to 100:2)
as an eluant. The product obtained by evaporating the elude
(1.45 g) under vacuum was found to be identical to the titled
compound by NOR analysis.
(c) The titled compound could also be produced by the
following method.
3-tN-cyclohexanecarbonyl-D-alanylthio)-2-D-meth
propanoic acid (4.52 g) was dissolved in thionylchloride
, "by .
- 26 - ~35~20
(S ml). To the solution, a drop of dimethylformamide was
added and the mixture was stirred at room temperature over-
night. The mixture was evaporated under vacuum to remove the
solvents, and to the residue, dry Tulane (2 ml) was added,
and the mixture was again evaporated under vacuum to remove
the solvent. To the residue, dry tetrahydrofuran 110 ml) was
added under stirring. The tetrahydrofuran solution containing
the acid chloride was added drops at a temperature between
5 and 10C under stirring to water (25 ml) having praline
(2.3 g) and Nikko (2.5 g) dissolved therein. The mixture
was stirred at that temperature for one hour, and at room
temperature for two more hours. The reaction mixture was
subjected to extraction with chloroform. To the aqueous
layer, ON Hal was added to adjust its pi to between l and 2.
After extraction with chloroform, the chloroform layer was
washed with saturated Nail solution twice, and dried over
magnesium sulfate. After removal of chloroform, the residue
was subjected to column chromatography on silica gel using
a mixture of chloroform and methanol (100:1 to 100:2) as an
eluant. Upon evaporation under vacuum, a gummy substance
(1.6 g) was obtained. That substance was found to be identical
with the titled compound by NOR analysis.
(d) The titled compound could be produced by yet another
method that is described below.
3-(N-Cyclohexanecarbonyl-D-alanylthio)-2-D-methyl---
propanoic acid (3.01 g) and t-butyl ester of L-proline (1.71 g)
were dissolved in dry dichloromethane (50 ml), and duskily-
hexylcarbodiimide (2.15 g) was added to the solution under
~;~3~120
- 27 -
stirring and cooling with ice. The mixture was stirred at
Ct~q
A the same temperature for half Lowry and left overnight
at 5C. The reaction mixture was filtered and the insoluble
matter was washed with dichloromethane. The filtrate and
the washings were combined and washed with lo Hal, water,
lo Nikko and saturated Nail solution in the order mentioned,
dried over McCoy and evaporated under vacuum to provide a
gummy sample of t-butyl ester of N-[3-(N-cyclohexanecarbonyl-
D-alanylthio)-2-D-methylpropanoyl]-L-proline (4.3 g). A 4.0 g
sample of the ester was dissolved in anisole (30 ml), and
trifluoroacetic acid (10 ml) was added to the solution. The
mixture was stirred at room temperature for one hour and
evaporated under vacuum to remove excess trifluoroacetic acid.
The residue was subjected to column chromatography on silica gel
(column: 2 x 35 cm) using a mixture of methanol and sheller-
form (1:100 to 3:100) as an eluant. Fractions containing the
end compound were collected and evaporated under vacuum to
obtain a gummy substance (3.4 g). That substance was found
to be identical with the titled compound by NOR and thin-layer
chromatography.
The reactants, reaction solvents and the methods used
for producing the titled compound in Example 3 are listed in
the following table together with data on its physical prop-
reties. Other compounds were prepared by using one of the
methods described in Example 3, (a) to (d), and particulars
of the specific method are listed in the following table
together with data on the physical properties of the end
compounds. In the table, the figures following numbers (1)
~23~;~20
- 28 -
and (2) in the column of "Of value" indicate the Of values
obtained in thin-layer chromatography using CHC13/MeOH/AcOH
(2:1:0.003) and n-BuOH/AcOH/H20 (4:1:1) as eluants, respectively.
~:353L~)
-- 29 --
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_ 30 - 5120
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- 31 _ ~235j~
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- 32 - ~L235~1LZO
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Example 4
Various salts were formed from the samples of NUN
Acyclohexanecarbonyl-D-alanylthio)-2-D-methyl~rcp~Noah -L-proline
prepared in Examples 3 and 5.
(a) Cay salt
A 3.98 g sample of the compound prepared in Example 3
or 5 was dissolved in methanol (40 ml). To the solution,
calcium acetate hydrate (0.84 g) was added, and the mixture
was heated under reflex for one hour. The insoluble matter
was filtered off and the filtrate was evaporated under vacuum.
To the residue, chloroform was added, and the mixture was
filtered and evaporated under vacuum. To the residue, deathly
ether was added, and the mixture was filtered and dried with
air to give a calcium salt of the compound of Example 3 or
15 5 (3-40 g)- [and = -47.2 (C=1.0, Mesh)
(b) My salt
The procedure of (a) was repeated using 3.09 g of the
compound prepared in Example 3 or 5 and 0.772 g of magnesium
acetate tetrahydrate. A magnesium salt of the compound of
20 Example 3 or 5 was produced (2.42 g). [and = -46.6 (C=1.0, Mesh)
(c) Lawson salt
A 1.19 g ox the compound prepared in Example 3 or S
was dissolved in methanol (22 ml). To the solution, Lawson
(0.416 g) was added, and the mixture was stirred at room temper-
azure for one hour, and evaporated under vacuum. To the residue,
chloroform was added, and the mixture was filtered and evapo-
rated under vacuum. To the residue, dim ethyl ether was added,
and the product was filtered by suction to give a Lawson salt
~235120
- 34 -
of the compound of Example 3 or 5 (1.54 g)- Do = -23.1
(C=1.0, Mesh)
(d) No salt
A 2 . 27 g sample of the compound prepared in Example 3
or 5 was dissolved in methanol (25 ml). To the solution,
0.514 g of sodium acetate was added, and the mixture was
stirred at room temperature for 30 minutes, and evaporated
under vacuum. To the residue, 200 ml of a mixture of methanol
and chloroform (3:100 v/v) was added, and the resulting mixture
was filtered and evaporated under vacuum. The residue was
dissolved in methanol, and the solution was filtered and evapo-
rated under vacuum. To the residue, ethyl acetate was added,
and the product was filtered by suction to give a No salt of
the compound of Example 3 or 5 (1.85 g). [and = -26.7
(C=1.0, Mesh)
(e) Dicyclohexylamine salt --
A 13.1 g sample of the compound of Example 3 or 5 was
dissolved in 120 ml of acetonitrile. To the solution, dip
cyclohexylamine (6 ml) was added under stirring. The mixture
20 was further stirred for 30 minutes, and then left overnight.
The precipitate was filtered by suction and dried in the air.
The resulting crude crystal was suspended in 300 ml of
acetonitrile, and the suspension was heated under reflex for
30 minutes. The suspension was cooled and the crystal was
filtered by suction and dried in the air to give a duskily-
hexylamine salt of the compound of Example 3 or 5 tl2.2 g).
Do = -24.5 (C=1.0, Mesh)
_ 35 _ 123~20
Example 5: N-[3-(N-Cyclohexanecarbonyl-D-alanylthio)-2-D-
methylpropanoyl]-L-proline
N-Cyclohexanecarbonyl-D-alanine (5.98 g) was dissolved
in dry tetrahydrofuran (80 ml). To the solution, carbonyl-
diimidazole (5.84 g) was added at -18C under stirring while
the mixture was cooled with ice. The mixture was stirred at
that temperature for one hour, and thereafter, N-(3-mercapto-
2-D-methylpropanoyl)-L-proline (6.23 g) was added to the
mixture, followed by stirring at -18~C for 30 minutes, then
at room temperature for one hour. After completion of the
reaction, the mixture was evaporated under vacuum to remove
the solvent. To the residue, water (50 ml) was added, and
2N-HCl was added to the mixture to adjust its pi between
1 and 2. The mixture was extracted with ethyl acetate, and
the ethyl acetate layer was washed with saturated Nail soul-
lion, dried over McCoy and evaporated under vacuum. To Thursday, acetonitrile (120 ml) was added, then 6 ml of dip
cyclohexylamine (DCHA) was added. The mixture was stirred at
room temperature for one hour. After standing overnight, the
precipitate was filtered and dried in the air to give a crude
DCHA salt (14.35 g). The crude salt was suspended in asset-
nitrite (300 ml) and the suspension was heated under reflex
for 30 minutes. After cooling, the precipitate was collected
by suction and dried in the air to give a white DCHA salt
(12.20 g). The DCHA salt (12.20 g) was suspended in ethyl
25 acetate (90 ml) and to the suspension, 0.5N aqueous KHSO4
(60 ml) was added, and the mixture was shaken. The organic
layer was washed with distilled water, dried on McCoy and
- 36 ~Z3~1Z~;)
evaporated under vacuum to give a gummy substance (8.64 g).
That substance was found to be identical with the titled
compound by NOR analysis and thin-layer chromatography.
Example 6: N- [3- (~-Cyclohexanecarbonyl-glycylthio) -2-D- -
methylpropanoyl]-L-proline
N-Cyclohexanecarbonyl-glycine (1.02 go was dissolved
in dry tetrahydrofuran (10 ml). To the solution, 20 ml of
dry tetrahydrofuran containing 1.07-g of carbonyldiimidazole
was added at -20C under stirring while the mixture was cooled
with ice. The mixture was stirred at that temperature for
one hour, and thereafter, 6 ml of dry tetrahydrofuran contain-
in 1.09 g of N-(3-mercapto-2-D-methylpropanoyl)-L-proline
was added, followed by stirring at -20C for 30 minutes,
then at room temperature for one hour. After completion ox
the reaction, the mixture was evaporated under vacuum to remove
the solvent. The residue was subjected to column cremate-
graph on silica gel (column: 2 x 35 cm) using a mixture of
methanol and chloroform (1:100 to 3:100~ as an eluant. Free-
lions containing the end compound were combined and evaporated
under vacuum to give a gummy substance (1.16 g). The substance
was found to be identical with the titled compound by NOR
analysis and thin-layer chromatography.
Example 7: N-~3-(N-Cyclopropanecarbonyl-D-alanylthio)-2-D-
methylpropanoyl]-L-proline
N-Cyclopropanecarbonyl-D-alanine (635 my) and in-
ethyl amine (0.70 ml) were dissolved in dry tetrahydrofuran
25 (14 ml). To the solution, ethyl chloroform ate (0.48 ml) was
added at -15C under stirring while the mixture was cooled
with ice. The mixture was stirred at that temperature for
, .
37 - ~Z3S120
15 minutes, and thereafter, N-(3-mercapto-2-D-methylpropanoyl)-
L-proline (1.09 g) and dry tetrahydrofuran (10 ml) containing
triethylamine (0.70 ml) were added, followed by stirring at
-15C for 15 minutes, then at 5C overnight. After completion
of the reaction, the mixture was evaporated under vacuum at
30 - 35C to remove the solvent. To the residue, water (10 ml)
was added, and 2N-HCl was added to the mixture to adjust its
pi to between 1 and 2. The mixture was extracted with sheller-
form, and the chloroform layer was washed with saturated Nail
solution, dried over McCoy and evaporated under vacuum. The
residue was subjected to column chromatography on silica gel
(column: 2 x 35 cm) using a mixture of methanol and sheller-
form (1:100 to 3:100) as an eluant. Fractions containing the
end compound were combined and evaporated under vacuum to give
a gummy substance (395 my). That substance was found to be
identical with the titled compound by NOR analysis and thin-
layer chromatography.
Example 8: N-[3-(N-Cyclohexanecarbonyl-N-methylglycylthio)-
2-D-methylpropanoyl]-L-proline
The procedure of Example 6 was repeated except that
N-cyclohexanecarbonyl-glycine was replaced by N-cyclohexane-
carbonyl-N-methylglycine (1.09 g), carbonyldiimidazole (1.09 g)
and N-(3-mercapto-2-D-methylpropanoyl)-L-proline (1.09 g).
A gummy substance (0.76 g) was produced and it was found to
be identical with the titled compound by NOR analysis and
thin-layer chromatography.
Example 9: N-~3-(N-Cyclopropanecarbonylglycylthio)-2-D-
methylpropanoyl]-L-proline
The procedure of Example 6 was repeated except that
- 38 lo 3S~2~
N-cyclohexanecarbonyl-glycine was replaced by N-cyclopropane-
carbonylglycine (0.96 g), carbonyldiimidazole (1.09 g) and
N-(3-mercapto-2-D-methylpropanoyl)-L-proline (1.09 g). A
gummy substance (0.4 g) was produced and it was found to-be
identical with the titled compound by NOR analysis and thin-
layer chromatography.
Example 10: N-[3-(N-Adamantanecarbonylglycylthio)-2-D- -
methylpropanoyl]-L-pro-line
The procedure of Example 6 was repeated except that
N-cyclohexanecarbonyl-glycine was replaced by N-adamatane-
10 carbonylglycine (1.42 g), carbonyldiimidazole ~1.09 g) and
N-(3-mercapto-2-D-methylpropanoyl)-L-proline (1.09 g). A
gummy substance (1.7 g) was produced and it was found to be
identical with the titled compound by NOR analysis and thin-
layer chromatography.
Example 11: N-[3-(N-Cyclohexanecarbonyl-D-phenylalanylthio)-
2-D-methylpropanoyl]-~-proline
The procedure of Example 6 was repeated except that
N-cyclohexanecarbonyl-glycine was replaced by N-cyclohexane-
carbonyl-D-phenylalanine (1.54 g), carbonyldiimidazole (1.09 g)
and N-(3-mercapto-2-D-methylpropanoyl)-L-proline (1.09 g).
A gummy substance (0.97 g) was produced, and it was found to
be identical with the titled compound by NOR analysis and
thin-layer chromatography.
Example 12: N-[3-(N-Cyclohexanecarbonyl-D-leucylthio)-2-D-
methylpropanoyll-L-proline
The procedure of Example 6 was repeated except that
N-cyclohexanecarbonyl-glycine was replaced by N-cyclohexane-
carbonyl-D-leucine (1.20 g), carbonyldiimidazole (0.97 g)
,, " )
- 39 - 12 3S~0
and N-(3-mercapto-2-D-methylpropanoyl)-L-proline (0.98 g).
A gummy substance (1.17 g) was produced and was found to be
identical with the titled compound by NOR analysis and thin-
layer chromatography.
Example 13: N-[3-(N-Cyclohexanecarbonyl-D-tryptophylthio)-
2-D-methylpropanoyl]-L-proline
The procedure of Example 6 was repeated except that
N-cyclohexanecarbonyl-glycine was replaced by N-cyclohexane-
carbonyl-D-tryptophan (1.75 g), carbonyldiimidazole (1.09 g)
and N-(3-mercapto-2-D-methylpropanoyl)-L-proline (1.09 g).
A gummy substance (0.8 g) was produced and it was found to
be identical with the titled compound by NOR analysis and
thin-layer chromatography.
Example 14: N-[3-(N-Cyclohexanecarbonyl-D-phenylglycylthio)-
2-D-methylpropanoyl]-L-proline
The procedure of Example 6 was repeated except that
N-cyclohexanecarbonyl-glycine was replaced by N-cyclohexane-
carbonyl-D-phenylglycine (1.30 g), carbonyldiimidazole (0.97 g)
and N-(3-mercapto-2-D-methylpropanoyl)-L-proline ~0.98 g).
A gummy substance (0.35 g) was produced and was found to be
identical with the titled compound by NOR analysis and thin-
layer chromatography.
Example 15: N-[3-(N-Cyclohexanecarbonyl-D-methionylthio)-
2-D-methylpropanoyl]-L-proline
The procedure of Example 6 was repeated except that
N-cyclohexanecarbonyl-glycine was replaced by N-cyclohexane-
carbonyl-D-methionine (1.30 g), carbonyldiimidazole (1.09 g)
25 and N-(3-mercapto-2-D-methylpropanoyl)-L-proline (1.09 g).
A gummy substance (0.59 g) was produced and it was found to
~'~3~20
- 40 -
be identical with the titled compound by NOR analysis and
thin-layer chromatography.
Example 16: N-[3-(N-Cyclohexanecarbonyl-D-glutaminylthio)-
2-D-methylpropanoyl]-L-proline
The procedure of Example 6 was repeated except that
N-cyclohexanecarbonyl-glycine was replaced my N-cyclohexane-
carbonyl-D-glutamine (0.5 g), carbonyldiimidazole 10.41 g)
and N-(3-mercapto-2-D-methylpropanoyl)-L-proline (0.41 g).
A gummy substance (0.3 g) was produced and was found to be
identical with the titled compound by NOR analysis and thin-
layer chromatography.
Example 17: N-[3-(N-Adamantanecarbonyl-D-alanylthio)-2-D-
methylpropanoyl]-L-proline
The procedure of Example 6 was repeated except that
N-cyclohexanecarbonyl-glycine was replaced by N-adamantane-
carbonyl-D-alanine ~1.2 g), carbonyldiimidazole Tao g) and
15 N-(3-mercapto-2-D-methylpropanoyl)-L-prollne (0.98 g). A
gummy substance (1.02 g) was produced and was fount to be
identical with the titled compound by NOR analysis and thin---
layer chromatography.
Example 18: Dicyclohexylamine salt of N-[3-(N-cyclohexane-
carbonyl-D-alanylthio)-2-D-methylpropanoyl]-L-
praline
if) 3-(N-Cyclohexanecarbonyl-D-alanylthio)-2-D-methyl---
propanoic acid (241 g) was suspended in dry dichloromethane
(1.3 liters). To the suspension, triethylamine (1~7 ml) was
added drops at -15C under stirring, then pivaloyl
chloride ~104 ml) was added drops at below -5C under
stirring, and the mixture was further stirred for 30 minutes.
(2) L-Proline (101 g) was suspended in dry dich~oromethane
. I. .
- 41 - ~3~12~
(1.2 liters). To the suspension, trimethylsilyl chloride
(112 ml) was added drops at -15C under stirring, then
triethylamine (122 ml) was added drops at below -5C under
stirring, and the mixture was further stirred at -15C for
30 minutes. To the resulting mixture, the solution prepared
in (1) was added, and the mixture was stirred under cooling
for 15 minutes, then at room temperature for one hour. After
completion of the reaction, cold distilled water (1 liter)
was added to the reaction mixture under cooling, and then
concentrated hydrochloric acid (90 ml) was added drops.
The mixture was stirred for 10 minutes and the organic layer
was separated, washed with saturated Nail solution twice,
cur/ en
A and triad over magnesium sulfate. To the filtrate, duskily-
hexcylamine (326 ml) and acetonitrile (800 ml) were added,
and the mixture was stirred for 30 minutes. Thereafter,
four 800 ml portions of acetonitrile were added at an interval
of 10 minutes, and the resulting mixture was left to stand
overnight at 5C. The precipitate was filtered by suction
and dried in the air to give a crude sample of the titled
compound. The crude sample was dissolved in dichloromethane
(3 liters) while hot, and filtered. The filtrate was stirred
at room temperature for 30 minutes, and another four 750 ml
portions of acetonitrile were added at an interval of 10
minutes, and the resulting mixture was left to stand over-
night at 5C. The precipitate was filtered and dried in their to give a colorless sample of the titled compound (404 g).
mop. 190-191C, Do = -24.5 (C=1.0, Mesh)
- 42 - ~3S120
Example 19: Calcium salt of N- [3- (N cyclohexanecarbonyl-
D-alanylthio)-2-D-methylpropanoyl]-L-proline
A 404 g sample of the dicyclohexylamine salt prepared
in Example 18 was suspended in ethyl acetate (2 livers), and
to the suspension, 0.5N XHSO4 (2.5 liters) was added, and
the mixture was stirred for 10 minutes. The organic layer
was separated, washed with distilled water and dries on
magnesium sulfate. The filtrate was evaporated under vacuum,
and the residue was dissolved in acetone (1.2 liters). To
the acetone solution, distilled water (1.2 liters) and calcium
carbonate (36.6 g) were added, and the mixture was stirred
vigorously at 40C for an hour. After cooling, the mixture
was filtered and the filtrate was evaporated under vacuum.
The resulting syrup was suspended in acetone (1 liter) and
the solution was stirred for 5 hours. The precipitate was
filtered by suction, dried in the air, then vacuum-dried to
give a white powder of the titled compound ~212 g).
Do = -47.2 (C=1.0, Mesh)
. _
