Note: Descriptions are shown in the official language in which they were submitted.
2328
Inhibitor3 o angioten~in-converting enzymes
are useful in the treatment o cardlova~cular di~orders
aspecially a~ antihypQrtensivo agents and al~o in the
treatment of congostive heart failure and oÇ
glaucoma~ Such ACE-inhibitorY have, or axample, been
described in tha published European patent applications
No~. 50800 and 79022-
Of particula~ interest as ACE-inhibitor~ are
compound~ o the general ~ormula (I)
Y~
R-~- ~ -NH-~H-~;N -CH _~_R6
~ ~ ~.* *
and tho pharmaceutically acceptable ~alt.~ thereof,
wherein R and R6 are ~he same or different and are
hydroxy, lower alkoxy, lower alkanoxy, diloweralkyl-
amino lower alkoxy (e.g. dimethylaminoethoxy),
acylamino lower alkoxy (e.g. acetylaminoethoxy),
--2--
acyloxy lower alkoxy (e.g. pivaloyloxyethoxy), aryloxy
(e.g. phenoxy), arylloweralkoxy (e.g. benzyloxy),
amino, lower akylamino, diloweralkylamino, hydroxy-
amino, aryllower alkylamino (e.g. benzylamino),
or substituted aryloxy or substituted arylloweralkoxy
wherein the substituent is methyl, halo or methoxy;
Rl is hydrogen, alkyl of from 1 to 10
carbon atoms, including branched and cyclic and
unsaturated (e.g. allyl) alkyl groups, suhstituted
lower alkyl wherein the substituent: is hydroxy,
lower alkoxy, aryloxy (e.g. phenoxy), substituted
aryloxy, heteroaryloxy, substituted heteroaryloxy,
amino, lower alkylamino, diloweralkylamino, acylamino,
arylamino, substituted arylamino, guanidino, imi-
dazolyl, indolyl, lower alkylthio, arylthio (e.g.
phenylthio), substituted arylthio, carboxy, carbamoyl,
lower alkoxycarbonyl, aryl (e.g. phenyl or naphthyl),
substituted aryl, aralkyloxy, substituted aralkyloxy,
aralkylthio, or substituted aralkylthio, wherein
the aryl or heteroaryl portion oE said substituted
aryloxy, heteroaryloxy, arylamino, arylthio, axyl,
aralkyloxy or aralkylthio groups is substituted
with a group .selected from halo, loweralkyl, hydroxy,
lower alkoxy, amino, aminomethyl, carboxyl, cyano
and sul~amoyl; and
R3 is hydrogen, lower alkyl, phenyl lower
alkyl, aminome-thylphenyl lower alkyl, hydroxyphenyl
lower alkyl, hydroxy lower alkyl, acylamino
lower alkyl (e.g. benzoylamino lower alkyl or
acetylamino lower alkyl), amino lower alkyl, dimethyl-
amino lower alkyl, guanidino lower alkyl, imidazolyl
lower alkyl, indolyl lower alkyl, or lower alkylthio
lower alkyl.
As used herein, acyl includes -C-R12
wherein R12 is lower alkyl, lower alkenyl or aryl.
--3--
The lower alkyl or lower alkenyl groups except
where noted otherwise are represented by any of
the variables including straight and branched chain
hydrocarbon radicals from one to six carbon atoms,
for example, methylt ethyl, propyl, isopropyl,
butyl, isobutyl, t-butyl, pentyl, isopentyl, hexyl
or vinyl, allyl, butenyl and the like. Cycloalkyl
groups include bridged and non-bridged groups.
The aralkyl groups represented by any of the above
variables have from one to four carbon atoms in
the alkyl portion thereof and include for example,
benzyl, p-methoxybenzyl and the like. Halo means
chloro, bromo, iodo or fluoro. Aryl, where it
appears in any of the radicals, except where noted,
represents phenyl or naphthyl. Heteroaryl groups
where~ they appear include for example pyridyl,
thienyl, furyl, indolyl, benzothienyl, imidazolyl
and thiazolyl. The Rl and R3 substituted lower alkyl
moieties are çxemplified by groups such as
~ ~LCH2_ ~ ~CH2 ~H2--
H H
HC-CH2-' HS-CH2-~ H2N-(cH2)4-, CH3~S-(CH2)2_,
NH
2 (CH2)3 , H2N C-NH-(CH2)3- and the like-
Preferred compounds of formula I are
those in which R is hydroxy or lower alkoxy, Rl
is lower alkyl or sub3tituted lower alkyl wherein
the substituent is aryl, R3 is lower alkyl or amino-
loweralkyl and R6 is hydroxy.
The aforementioned compounds of the formula
I, as defined above, include all possible stereo-
--4--
isomers. Preferred stereoisomers are the cls,endo-
octahydrocyclopenta[b]pyrrole-2(S)-carboxylic acids,
wherein preferably the absolute configuration at
the carbon atoms marked by a double asterisk in
the above formula I is most similar to that of
natural L-amino acids, which usually are assigned
the S-configuration. Particularly preferred compounds
are l-[N-(l(S)-carboxy-3-phenylpropyl)-(S)-alanyl]-
cis,endo-octahydrocyclopenta[b]-pyrrole-2(S)-
carboxylic acid, l-[N-(l(S)-carboethoxy-3-phenyl-
propyl)-(S)-alanyl]-cis,endo-l
octahydrocyclopenta[b]pyrrole-2(S)-carboxylic acid,
l~N ~-(l(S)-carboethoxy-3-phenylpropyl)-(S)-lysyl]-
cis,endo-octahydrocyclopenta~bJpyrrole-2(S)-carboxylic
acid, l-~N~-(l(S)-carboxy-3-phenylpropyl)-(S)-lysyl]-
cis,endo-octahydrocyclopenta~b]pyrrole-2(S)-carboxylic
acid, l-~N-(l(S)-carboxybutyl)-(S)-alanyl] cls,endo-
octahydrocyclopen-ta~b]pyrrole-2(S)-carboxylic acid,
l-~N-(l(S)-carboethoxybutyl)-(S)-alanyl]-cls,endo
octahydrocyc:lopenta~b]pyrrole-2(S)-carboxylic acid,
1-~N ~ -(l(S)-carboethoxybutyl)-(S)-lysyl]-cls,endo-
octahydrocyclopenta~b~pyrrole-2(S)-carboxylic acid,
and 1-~N ~ (l(S)-carboxybutyl)-(S)-lysyl]-cls,endo-
octahydrocyclopenta~b]pyrrole-2(S)-carboxylic acid
or their hydrochloride salts. A most preferred
compound is l-~N-(l(S)-carboethoxy-3-phenylpropyl)-
(S)-alanyl]-cls,endo-octahydrocyclopenta~b]pyrrole-2-
(S)-carboxylic acid and its hydrochloride salt.
These compounds can be prepared by known
methods such as described in the above mentioned
European published patent applications Nos. 50800
and 79022.
One of the starting materials for the
preparation of compounds of formula I is oc-tahydro-
cyclopenta~b]pyrrole-2-carboxylate, III,
.~
~S$
wherein R6 is a~ ds~ined abov~.
Compound~ o for~ul~ conYl~t o~ eiqht
st2reoisomer~ co~po~d of ~our race~lc pa~r~ the two
Ci9 epimer~, IIIa and IlIb, and the two tran~ epimsrs,
IIIc and rIId:
~t:oR~ ~ ~COR6
(~) IIIa (~ IIIb (~ IIlc
116
(~ IISd
A~ u~ed herQin, the fo~mulae III~, IIIb, IIIc and IIId
are meant to co~pri~o the rel~vant racQmic pair of
optical isomer~.
The compound~ of formula III can be prapared
by known mathods, suoh a~ di~cloqed in ths publicationq
mentioned above, followod, if de~ired, by isolation of
the racemic pairs of isomers or their individual component
enantiomers according to resolution methods well described
in the art.
The present invention provides a novel
process for the preparation of the compounds of the
- 6 ~
~en~ral fon~ula IIIJ9 Th~ proce~9 compri~e~ c~talytic
rcduc~lon o~ co~pound I~
N ~
C~2C~j~S
wharein R6 i5 a defined above, followed, if desired by
the resolution of the racemic mixture to obtain the
individual enantiomer.
Compound II can be prepared by the reaction
o a halopyruvat~ e~ter (V)
Hal-CH2-~ R6
wherein R6 i3 as deflned above and Hal stands for
halogen, with benzylimlnocyclopentane.
Thi3 procedure can be exempli~ied by the
followlng reaction schemes
OD~N-CN2-C6~S I ar CH2 ~ ~ R
~V ~Ja,
iC2H5)3~
~ co~6 ~
I P~/C IIIa
C~2C6~5
t~
~7-
The ~roc3~ for preparing tho novel compound~
~ benzyl~ 5,6-~otrahydrocyclopent~n0[b]pyrrolo-
2-carboxylic aGid or it o~ters) pr~ferably u~e~ a
lower alkyl ester of bromo pyruvate (a.g. R6 i~ othoxy,
methoxy or t~butoxy)O Pref~rably, equimolar amounts of
reac~ant~ are used. The r~actio~ i~ carried out in an
in~rt ~olvent such a~, for exa~ple, an alcohol (ocg.
ethanol), acetoni~r~le or dim~thylform~ide in the
pre~ence of a b~e ~uch a~, for exa~pl~, triothyl-
amine. The reactlon may bo carried out at from 0-100C
for 2-~ hour~, but i~ preferably carried out at low
temperature~ (e.g. 0-5C) for approximately 2 hours,
then at re~lux (temperature depends on ~olvent) for 2
hours.
The catalytic reduction o~ compound II to
saturate the ring and remove the benzyl g~oup is
carried out in a solvent such a~ an alcohol (e.g.
ethanol) in the presence of hydrogen gas and a cataly~t
such as Pd(OH)2 on carbon, Pd on carbon or other
appropriate cataly~t~. The resultant product may be
i~olated by me~hods woll known to those skilled in the
art, e.g. by treAting wlth an acid such as HCl to
prepare the salt, followad by removal of the salt ~e.g.
by basifying with 30dium hydroxid~) to obtain the
compound of formula IIIa, followed, if desired by the
isolation of the individual enantiomers.
In the above reactions, the group R6 being
other than hydrogen (especially aryllower alkyl) can be
hydrogenolyzed to some extent. Consequently, an addi-
tional esterification step may be required to obtain
the desired compound.
The above described process is stereospecific
so that compounds IIIa (cis,endo-form)are obtained
directly. These compounds are useful in the
-8~
preparation of the preferred compounds of formula I
(listed above) which are also the cis,endo-isomers.
This i9 a great advantage over the known method for
preparing compounds of formula (III) which are not
stereospecific so that additional process steps have to
be carried out to isolate the desired isomer of the
intermediate (III) or of the end product (I).
Compounds IIIa as obtained by this process are
racemic mixtures. The individual enantiomers can
be obtained by conventional resolution methods well
described in the art such as fractional crystallization
of appropriate diastereomeric salts, for example the
fractional crystallization of compounds IIIa wherein R
is benzyloxy or its benzyloxycarbonyl-L-phenylalanine
salt.
The compounds of formulae IIIa (cis,endo-
forrn) can be converted to the correspondin~
compounds having the cis-exo~form (IIIb)~ Such
epimerizations are most conveniently carried out on
the free base ester forms of the.se compounds, in the
absence or presence of additional basic catalysts such
as potassium t-butoxide, triethylamine and the like.
The following examples illustrate the process
of this invention, the preparation and use of the
compounds of the present invention. The diastereoisomers
prepared as set forth below may be isolated by column
chromatography or by fractional crystallization.
.9_
liX~PLE 1
CARI!IOXYl.ATE
Add dro~wi~ 3 . 9 gm o ethyl bromopyruvata in
50 ml of ethanol to a fla~k COnt21iniR9 3-46 910 oi~
benzyliminocyclopflntanQ and 2.09 o~ triethylaroin~ in 50
ml of ethanol at 0C~ stir ~or 2 hourY, then heat to
re1ux for 2 hour~. Concentrate th~ reaction mixture
and partltion betwaen lN HCl and ~thor. Dry the ether
axtract over magne~ium ~ulfate, filtor, concen~rate
under high vacuum to obtain a brown oil and diqtlll in
a kugelrohr at 190-210/0.1 mm to bbtain the title
compound of Part A a~ a yellow oil.
B. Ethyl Ci~,Endo-octahydrocyclopen~a[ble~rrole-2
CarboxYlate H~,cdrochiorideO
Introduce hydrogen ga~ to a mlxture oF 2O3 gm
o~ the pyrrole compound produced in part A ~-
of this Example and 1.5 gm o 20~ Pd(OH)2/C in 200 ml
o~ ethanol, and ~tir the reaction mixture. Ater 24
hours add an additional 0.8 gm of the palladium
catalyst. After 600 ml o~ hydrogen gas is absorbed,
filter the reaction mixture and concentrate to obtain a
liquid and a solid. Take up thQ liquid in ether and
filtsr. Treat the filtrate with 2.86N HCl/e~her to
obtain an oil which ~olidifies. Filter off the ~olid
to obtain the hydrochlorid~ salt of the title compound
of Part B as a beige solid. m.p~ 163-7C.
~ecrystallization from CH2C12 and hexano raises the
melting point to 171-2C.
--10--
c~
Acid.
Stir a ~ixture o2 10.7 ~ o~ ~thyl ci~, ndo-
octahydrocyclop~n~2[b]pyrrole-2-carboxylat~
hydrochlorids (fro~ Part ~ abov3) and 175 ml of lN
sodium hydroxide at room tem~era~ur~ for 20 hours and
then concentrat~ in vw uo. Place tha rQ~idue on a
_ __
silica gel (1000 ~, 69-200 m~sh~ colu~n and ~lute with
chlorofor~:isopropanol:7~ ammonium hydroxid~ lsl~l
(organic layer) to give cl3,endo-oct~hydrocyclopanta-
[b]pyrrole 2-carboxyl~c acld, as a white ~olid, m.p.
220~222C: TLC: Rf 0.12 ~0.25 mm silicaJ ~
CHC13:isopropanol:7~ NH4OH~ low~r pha~e): MS: 156,
155 ~M+), 126 ~M-HCO), 111 (M-CO2), 110 (M-CO2H; 100%),
93 [M-H(CH2)3]~ 82 (M-CH2~CHCO2H), ~0 (M~
H2,CH2~CHCO2H), 68 lM-CO2H, (CH2)3], 67 lM-I
HC02H,(CH2)3] .
MR (400 MHz-D20)~ ~ 4.39 (lH doublet of doublet~
J~llHz,8Hz); 4.20 (lH multiplet);
3.00 (lH multiplet); 2.66 ~lH
multiplet); 2.03-1.18 t6H
multiplet); 1.S7 (lH multiplet).
EXUli'LE Z
1- [N- ( 1 ( R, S ~CAR90ETHOXY-3-PHENYLPROPYI. ) - ( S ) -
ALANYL]-CIS,E_DO-:)CTAHYDROCYCLOPENTA[b¦ PYRROLE-2(S)-
CAI~OIIYLIC AC~D
A. To a solution of 10.0 9 of ethyl-cis,endo-
octahydrocyclopenta [bl pyrrole-2-carboxylate in 400 ml
o ethyl acetate add 17.0 g of N-benzyloxycarbonyl ~S)-
alanine, N-hydroxy~uccinimide ester. Stir the reaction
mixture at room temperatura for 20 hours and concen-
t ~
trat~ it in vacuoO Placo tho re~du~ on ~ colu~n ofsillc~ g~l (3000 9, 60-200 ~h) and elu ~ with
chlorofor~:ethyl acetata ln:l to obtain l-[N-benzyloxy-
c~r~onyl-~S ) -alanyll -ci~,sndo-oetahydrocyclop~nta lb] -
pyrrole-2-carboxylic acid, ethyl e3~er, a colorless oil
[~1D26-3~.6 (C ~ 0.5, ethanol).
~. To a ~olu~ion of 3.22 9 of l-lN-b~nzyloxy-
carbonyl-(S)-alanyl]-c~,endo-octahydrocyclo~enta-
[b]pyrrole-2-carboxylic acid, ethyl ester in 150 ~1 of
methanol, add 20 ml o~ 205 N sodium hydroxide and stir
the mixturs at room temparature for lB hour~.
Concentrate the mixturo under nitrogen, dilute the
residue with ice-water and then make the mixtura acidic
with concentrated hydrochloric acid. Extract tho
aqueous ~olution with ethyl acetate and dry the organic
phase over magnesium sulfate. Concentrate the organic
pha~e and place it on a column of ~ilica gel (500 9.,
60-200 mesh). Elute with chloroform:glacial acstic
acid 9:1 and i~olate l-lN-benzyloxycarbonyl-(S)-
alanyl]-cis,sndo-octahydrocyclo-penta[b]pyrrole-2(S)-
carboxylic acid, as a colorle~ oil, [al D26-26 .4 tC =
0.5, ethanol).
C. Dissolve 1.70 g of l-[N-~enzyloxycarbonyl-
(S)-alanyl]-ci~,endo-octahydrocyclopenta[b]pyrrole-
2(S)-carboxylic acid in 100 ml of methanol. Add 0.40 9
10~ palladium-on-charcoal and hydrogenate the mixture
at atmospheric pressure. ~ilter the mixture and
concentrate in vacuo to obta in l-[(S)-alanyl]-cis,endo-
oc tahydro-cyc lopenta ~b ] pyrrole~2 t S ) -carboxyl ic ac id .
D. Dissolve l-[(S)-alanyl]-cis,endo-octahydro-
cyclopentalblpyrrole-2ts)-carboxylic acid in 100 ml o~
12-
ab~olute m~thanol. Add 1.10 g 2-oxo-~-ph~nylbutyric
acld, ethyl ~t~r ~nd 20 ml of 3 Ang~trom ~olecular
qlevo pellet~ F and ~tlr th~ re~ulting ~ixture at roo~
te~perature for ei~hteon hour Filt~r th~ re~otion
mixture and tr~at the filtrate with 0.68 g sodium
cyanoborohydrid0 at roo~ tsmperatur~ for two hour~.
Concentrate the mixture under nitrogen ~nd dilut3 the
oil with dilute hydrochloric acid and ~tir at room
temperature for one hour. Ab~orb th~ aqu~ou~ solution
on 200 ml of a XAD-2 (Xohm ~ Haa~ Co. r~in). El~t~
the re in with 2000 ml of wat~r and then with 2000 ml
of methanol. Concentr~te th~ m~thanol ~olution and
place the residuo on a column of silica y~l ~400 9, 60-
200 me~h) and elute with chlorcform~isopropanol:73
ammonium hydroxida ~lsl~ organic layer) to give 1-
[N~ R,S)-carbosthoxy-3-phenylpropyl)-~S)-alanyl]-
ci~,endo-octahydrocyclopentalb]pyrrole-2(S)-carboxylic
acid, a~ a colorle9~ oil, 1al
-5.8 (C~10.6, ethAnol).
EXAMPLE 3
l-tN-~1~S)-CAR~OETHOXY-3-PHENYLPROPYL)-~S)-ALANYL]-
CIS,ENDO-OCTAHYDROCYCLOPENTA~b]PY~ROL~-2tS)-
CARBOXYLIC ACID AND THE HYDRO~HLORID~ SALT THEREOF_
Method I
A. Ci~ ,endo-Oetah~roeyeloE~nta ~b] pYrrole-2-Carboxylie
Aeid Hydroehloride
Method I Add a 20~ HCl in dioxane ~olution
( 100 ml) to 5 9. of eis,endo~
oetahydrocyclop~nta [b~ pyrrole-2-earboxylic acid. Stir
the resulting mixture at room temperature for 30 min.
and then concentrate it in vacuo. Wash the white
residue with anhydrou~ ether and dry in vacuo to obtain
-13-
the tltla co~ound o~ Part A a~ a whito ~olld, m.p.
20g-211,
M~thod II Dlssolve 0.2 9 o~ ethyl ci~,endo-
oc~hydrocyclopent~[bJpyr~ol~-2-Garboxylat~ (freo ba~a
or hydrochlorldo from Example 1 in 20 ml of 6N
hydrochloric acid and reflux over~ight. Cool the
reaction mixturo, r~move th~ v~la~ile~ under hLgh
vacuum and ob~ain th~ titlc product o~ P~rt Ao
B. To 5.0 9 of thc product of Part A, add 50 ml
of benzyl alcohol and 50 ml of thionyl chlorida and
~tir at room temperature. Concontrate the reaction
mixture ln vacuo and recry~tallize the residu~ rom
chloroform/ isopropanol to give benzyl Ci3 ,ando-
octahydrocyclopenta[bJDyrrole-2-carboXylate
hydrochlorida, m.p. 17S.
C. To 5.5 9 o~ the product of Part ~, add 2.6 g
of l-hydroxybenzotria~ole, 5.4 9 of N[l~S)-carboethoxy-
3-phenylpropyll-(S)-alanine and 4.0 9 o~ dicyclohexyl-
carbodiimide ln 80 ml of dimethyl formamide. Stir the
raaction mixtur~ at room temperature ~or 18 hour~.
Filter the reaction mixture, and add ethyl acetata to
the filtrate. Extract the ethyl acetate solution (3 X
200 ml) with 5~ aqueou~ codium bicarbonate.
Concentrate the dried ~MqSO4) ethyl acetate solution in
vacuo. Chromatograph the residue on a silica gel
column (400 g, 60-200 mssh) and eluta with ethyl
ace~ate/petroleu~ ether (30-60) 2~ olata, a~ tho
~irst eluted material, l-[N-(l(S)-carboethoxy-3-
-14-
phenylpropyl)~ al~nyl]- ~,ondo-octahydrocyclo-
penta[blpyrrol0-2~)-ca~boxylic a¢id benzyl ester~
. Hydrogenate 3.0 g o~ N-tl~ carboethoxy-
3-phenylpropyl~-(S)-alanyl]-ci~,endo-
octahydrocyclopcn~a,~b]pyrrola-2~s)-carboxylic acid
benzyl e~ter in 40 ml of ethanol contalning 0.5 9 of
10~ Pd/C. Remov~ the cataly~t by fileration and
concentrate th~ f iltrate in vacuo. Add absolute ether
to cry~talliæo l-lN ~l(S)-carboethoxy-3-phQnylpropyl)-
~S)-alanyl]-cis,endo-octahydrocyclo penta[b~pyrrole-
2(S)-carboxylic acid, m.p. 110-112C(d).
E. Add dropwi~o, with stirring, a solution o~
1.3 M hydrochloric acid in ether to tho product of Part
D until the mixture i9 pH2. Add 100 ml of ether and
continue to ~tir ~or 30 minuteR, then filter to obtain
l-[N-l~S)-carboethoxy~3-phenylpropyl)-~S)-alanyl]-
cis,endo-octahydrocyclopenta[b]pyrrole-2~S)-carboxylic
acid hydrochlorid~.
Method II
-
A. Stir a solution of 4.56 9 of N-[l(S)-
carboethoxy-3-phenylpropyl]-~S)-alanine, 2.20 g o~ N-
hydroxy-succinimida and 3.80 9 of 1-~3-dimethylamino-
propyl)-3-ethylcarbodlimide hydrochloride in 30 ml of
dimethyl-formamide for 18 hours at roo~ temperature.
Dilute the reaction ~ixture with ethyl acetate and wash
the ethyl acetate layer with saturated aqueous sodium
chloride. Concantrata thc dried (MqS04) ethyl acetate
solution to give N-[l(S)-carboethoxy-3-phenylpropyll-
(S)-alanine N-hydroxysuccinimide aster.
-15-
B. To a mixture of~ 3.76 g of the product of Part
A and 1.55 g of cls,endo-octahydrocyclopenta[b]-
pyrrole-2-carboxylic acid in 30 ml of I
dime-thylformamide, add 1.5 ml of triethylamine
and stir the resulting mixture at room temperature
for 18 hours. Concentrate the reaction mixture
ln vacuo and parti-tion between ethyl acetate and
H20 (adjusted to pH 4). Wash the ethyl acetate
solution with saturated aqueous sodium chloride.
Concentrate the dried (MgS04) ethyl acetate solution
ln vacuo and chromatograph the residue on a silica
gel (1000 ml) column using /: /: / CHC13/iso-PrOH/7~
NH40H(organic phase). Isolate l-[N-(l(S)-carboethoxy-
3-phenylpropyl)-(S)-alanyl]-clslendo-octahydrocyclo-
penta[b]pyrrole-2(S)--carboxylic acid as a foam.
EXAMPLE 4
ETHYL CISl EXO-OCTAHYDROCYCLOPENTA[b~PYRROLE-
2-CARBOXYLATE
Dissolve 0.4g of ethyl cls,endo-octahydro-
cyclopenta[b~pyrrole-2-carboxylate (as prepared
in Example 1) in 40 ml of ethanol and 7 ml of triethyl-
amine. Re~lux under nitrogen Eor five days. Remove
the volatiles ln vacuo and isolate. To obtaln
the hydrochloride salt of the product of this example,
treat the free base with ethereal HCL.
EXAMPLE 5
1-[N-(l(S)-CARBOXY-3-PHENYLPROPYL)-(S)~ LANYL]-CIS,
ENDO-OCTAHYDROCYCLOPENTA[b]PYRROLE-2(S)-CARBOXYLIC
ACID AND THE HYDROCHLORIDE SALT THEREOF
A. To a solution of 0.80g of l[N-(l(S)-carboethoxy-3-
phenylpropyl)-(S)-alanyl]-cls,endo-
~,
. ~ ~
--16--
oct~hydrocyclo~nta[b]~yrrol~-2~ c~rboxylie acid fro~
Exala~le 3 in 100 ~1 o meth~nol at 0-5C, ~dd 2.0 ml of
2 . 5N sodiu~ hydroxido $olution ~nd stir at room
temperatur~ for 24 hour~. Concen~:ra'c0 thi~ ~olutlon in
vacuo and absorb on 350 ml of AG50W-X2 ~o~R~d re~in
( 100-200 mesh, hydrogen form) . Wash the column with
w~er until th~ eluat~ i~ neutral and elu~a ~che product
with pyr$din~:~20 ~1:24). Concantr~t~ thQ ~luat~ $n
vacuo and chromal:ograph on a Lobar RP-8, size B column
(~. Merck) u~ing acetonitrile:wdter (2:3) a3 eluant to
obtain the title compound of thi~ example as the free
amino acid.
B. Treat an ethanol ~olution of the product of
Part A with one oquiv~lent of a lN solution o~
ethanolic hydrogen chlaride. Remove th~ 901vent in
vacuo at room tempecature to obtain the hydrochlorid~
~alt of the title compound of this example.
