CA1220214A - .beta.-OXO-.alpha.-CARBAMOYL-PYRROLEPROPIONITRILES - Google Patents

Abstract

.beta.-Oxo-.alpha.-carbamoyl-pyrrolepropionitriles Abstract of the Disclosure The invention concerns compounds of the formula I

(I) wherein Py is 2- or 3-pyrrolyl unsubstituted at the 1-position and optionally substituted at one or more of the remaining three positions by lower alkyl and/or by carboxy or lower carbalkoxy and/or by halogen; R is hydrogen or lower alkyl, and Ph is phenyl, unsubsti-tuted or substituted by one to three identical or different members selected from lower alkyl, lower alkoxy, lower alkylthio, lower alkylsulfinyl, lower alkylsulfonyl, hydroxy, halogen, trifluoro-methyl, nitro, amino and lower alkanoylamino; salts, especially pharmaceutically acceptable salts thereof; the lower alkyl enol ethers thereof; or the lower alkanoyl enol esters thereof.
They can be prepared, for example by removing the group Z
from a compound of the formula

Description

~2~2~

Case 4-14776/CGC 996 ~-Oxo-~-carbamoyl-pyrrolepropionitriles The present invention concerns new ~-(optionally substituted phenyl-carbamoyl)-pyrrolepropionitriles unsubstituted at the l-position of the pyrrole ring, of formula I or tautomers thereof CN
Py-CO-CH-CON-Ph (I) wherein Py is 2- or 3-pyrrolyl unsubstituted at the l-position and optionally substituted at one or more of the remaining three positions by lower alkyl and/or by carboxy or lower carbalkoxy and/or by halogen; R is hydrogen or lower alkyl; and Ph is phenyl, unsubsti-tuted or substituted by one to three identical or different members selected from lower alkyl, lower alkoxy, lower alkylthio, lower alkylsulfinyl, lower alkylsulfonyl, hydroxy, halogen, erifluOrO-: methyl, nitro, amino and lower alkanoylamino; salts, especially pharmaceutically acceptable salts thereof; the lower alkyl enol ethers thereof; or the lower alkanoyl enol esters thereof, process for their manufacture, pharmaceutical preparat.ions containing these compounds and their therapeutic application.

More particularly the invention relates to compounds of ormula I,or tautomers thereof, wherein Py represents 2- or 3-pyrrolyl un-substituted at the l-position and unsubstituted or substituted at one or more of the remainin8 three positions by one to three lower alkyl or halogen, by one carboxy or one lower carbalkoxy, or by one or two lower alkyl or halogen in addition to one carboxy or one , ~.,'~

~L22~)2~1L4 lower carbalkoxy; R is hydrogen or lower alkyl; Ph is phenyl ur~sub-stituted or substituted by one or two identical or different members selected from lower alkyl, lower alkoxy, lower alkylthio, hydroxy, halogen, nitro, amino and lower alkanoylamino; salts, especially the pharmaceutically acceptable salts thereof; the lower alkyl enol ethers thereof; or the lower alkanoyl enol esters thereof.

Preferred are compounds of formula I or tautomers thereof, wherein Py represents 2-pyrrolyl unsubstituted or substituted at one or more of the 3, 4 and 5-positions by one to three lower alkyl groups or by one or two lower alkyl groups in addition to one carboxy or one lower carbalkoxy group at the 3 or 4-positions; Ph is phenyl un-substituted or substituted by one or two identical or different members selected from lower alkyl, halogen, trifluoromethyl, lower alkylthio, hydroxy and lower alkoxy; R is H or lower alkyl; salts, especially pharmaceutically acceptable salts thereof; the lower alkyl enol ethers thereof; or the lower alkanoyl enol esters thereof.

Particularly preferred are the compounds of formula II or tautomers thereof ~O-CH-CONH-~\ ~ 3 (II) wherein each of Rl and R2 is hydrogen or lower alkyl; and each of R3 and R4 is hydrogen9 lower alkyl, lower alkoxy, hydroxy, halogen or trifluoromethyl; or a salt, especially a pharmaceutically accept-able salt thereof.

Further preferred are the compounds of formula II wherein Rl and R2 are hydrogen; each of R3 and R4 is hydrogen, alkyl with up to 4 carbon atoms, fluoro, chloro or trifluoromethyl; or a salt, especially a pharmaceutically acceptable salt thereof.

Highly preferred are the compounds of formula II, wherein each of Rl and R2 is hydrogen; and each of R3 and R4 is hydrogen, methyl, methoxy, fluoro, chloro or trifluoromethyl; or a salt, especially a pharmaceutically acceptable salt, preferably the sodium, potassium, calcium, triethylammonium or tris-(hydroxyethyl)ammonium salt thereof.

Particularly preferred are the said compounds of formula II, wherein at least one of R3 and R4 is different from hydrogen and is prefer-ably located at the para-position of the phenyl ring, and salts thereof, especially the pharmaceutically acceptable salts thereof, preferably the sodium, potassium, calcium, triethylammonium or tris-(hydroxyethyl)ammonium salt thereof.

The general definitions used herein have the following meaning within the scope of the present invention.

The term "lower" referred to above and hereinafter in connection with organic radicals or compounds respectively defines such with up to and including 7, preferably up to and including 4 and advantageous-ly one or two carbon atoms.

A lower alkyl group preferably contains 1-4 carbon atoms and represents for example ethyl, propyl, butyl or advantageously methyl.

A lower alkoxy group preferably contains 1-4 carbon atoms and represents for example ethoxy, propoxy, isopropoxy or advantageously methoxy; a lower alkylthio group preferably contains 1-4 carbon atoms and represents advantageously methylthio or ethylthio; a lower alkylsulfinyl group preferably contains 1-4 carbon atoms and represents advantageously methylsulfinyl or ethylsulfinyl; a lower alkylsulfonyl group preferably contains 1-4 carbon atoms and represents advantageously methylsulfonyl or ethylsulfonyl.

~2;~Z~

Halogen preferably represents chloro or fluoro but may also be bromo or iodo.

Lower alkanoylamino represents preferably acetylamino or propionyl-amino.

A lower carbalkoxy group represents preferably carboethoxy or carbomethoxy.

Tautomers of the compounds of formula I may be represented by the corresponding enol structure of formula Ia CN R
Py - C = C - C - N - Ph (Ia) OH O
wherein Py, R and Ph have the meaning as previously defined for compounds of formula I, and are in equilibrium therewith.

The compounds of formula I, being in equilibrium with their respective tautomers, have acidic properties and form9 as derivatives of the enolic tautomeric structure of formula Ia, lower alkyl enol ethers, lower alkanoyl enol esters, or salts thereof. Salts formed with pharmaceutically acceptable bases, such as alkali metal, alkaline earth metal, copper or ~inc hydroxides, ammonia, mono-, di- or tri-lower (alkyl or hydroxyalkyl)-amines, monocyclic amines or alkylene-diamines, are e.g. sodium, potassium, magnesium, am~onium, mono-, di- or tri-(methyl, ethyl or hydroxyethyl)-ammonium, pyrrolidinium, ethylenediammonium or morpholinium salts; or various hydrates thereof.

The compounds of the invention exhibit valuable pharmacological proper-ties, primarily antiinflammatory, analgesic (antinociceptive), anti-rheumatic, immunopotentiating andantiarthritic activity. These canbe demo~
strated by _-vitro or in-vivo tests, using for the latter advantageously ~L2;;~

mammals, such as rats, guinea pigs or dogs, as test objects. The compounds of the invention can be administered to the animals either enterally, preferably orallyy parenterally, e.g. subcutaneously or intravenously, or topically, for example, in the form of aqueous or oily solutions or starchy suspensions. The applied dosage may range between about 0.1 and 100 mg/kg/day, preferably between about 1 and 50 mg/kg/day. The tests chosen are among the classical assay methods for said activities, such as the carrageenin paw-edema, or adjuvant arthritis test in rats, the canine synovitis or ultra-violet erythema assays, or more recent tests, such as neutral protease inhibition [described in Arthritis Rheum. 17, 47 (1974)]
or inhibition of leukocyte chemotaxis [described in Ann. N.Y. Acad.
Sci., 256~ 177 (1975)]; or decrease of neutrophil adherence [described in AmerO J. Med~ 61, 597 (1976)]; or inhibition of prostaglandin synthetase [described in Biochem. 10, 2372 (1971)]; or the phenyl-quinone writhing test.
.Immunopotentiating effects are determined in BCG-immunized animals in-vitro and in~vivo.

Enhancement of cell-mediated immunity is determined in-v_tro as follows by measurement of increased chemotaxis of monocytes:

Male Charles River rats, weighing 250-300 g are immunized by intra-dermal injec,.ions of 0.1 ml Bacillus Calmette Guerin (BCG) vaccine.
One week later, the animals are injected with 10 ml of a sterile 2%
rice starch solution intraperitoneally, to induce the accumulation of macrophages. On day 11 after immunization, the animals are sacrificed and peritoneal macrophages collected with 20 ml of Gey' 9 buffered salt solution containing heparin (25 units/ml). The har-vested cells are centrifuged at 1000 RPM for 10 minutes, washed with 50 ml more of Gey's solution at the same speed and time, and then they are resuspended in Gey's solution containing 0.1% human serum albumin to yield a concentration of 2 x 10 cells/ml.

26~

The test substances are dissolved in dimethylacetamide to yield a l x lO M solution. Subsequent dilutions are made with Gey's solution, and they are finally added to the above cell suspension to yield the appropriate final concentrations of 10 , 10 , 10 and 10 M. Said sub-stances remain with the cells after the suspensions are distributed over the upper compartment of the modified Boyden chemotaxis chambers.
Escherichia coli lipopolysaccharide (Difco) activated rat serum (1/10 dilution at pH = 7.1) is used as the chemotactic agent and placed in the lower compartment of said chambers. The cell compartment of the chamber is separated from the chemotactic solution by a 8 micron pore size cellulose filter membrane, the chambers are set up in triplicate and incubated for 5 hours at 37C. Cell suspensions alone, without test compound, serve as controls for cell-migration.
After incubation, the filters are removed, fixed and stained with Weigert's iron hematoxylin9 and four fields of the lower surface of the filter are examined microscopically at a magnification of 320.
The average of the number of neutrophils counted in those four fields is used as an index of chemotactic activity.

The enhancernent of cell-mediated immunity is determined in-vivo in the BCG-immunized arthritic rat by measurement of delayed hyper-sensitivity reaction essentially as described in Current Therapeutic Research 30, S34 (1981).

Charles River male rats weighing 325-400 g are sensitized by intra-denmal injection into the right hind foot pad with 250 ~g per animal of Mycobacterium tuberculosis (Difco) emulsified in Freundls in-complete adjuvant. Animals are immunized with 0.1 ml of BCG vaccine intradennally on day 18 after adjuvant injection. Corn starch sus-pensions of drugs are administered orally. Control animals are dosed with cornstarch vehicle only. All animals are skin-tested with 10 ,ug PPD (purified protein derivative) intradermally on day 29 to elicit skin reactions. The diameter of the erythema and induration reaction is measured 24 hours after antigen challenge. An increase in the diameter of the eryehema is indicat;ve of enhanced cellular immunity.

The carrageenin paw-edema assay for antiinflammatory activity is carried out in rats as follows:

One hour after compounds are administered orally, 0.1 ml of carrageenin (1%) is injected into plantar area of one hind paw.
Difference of swelling is measured between contralateral and injected paw by means of mercury displacement at designated times.

The established adjuvant arthritis test for anti-arthritic activity is performed essentially as described in Proc. Soc. Exp. Biol. Med.
137, 506 tl971~. Analgesic activity (antinociceptive activity) is determined e.g. in the phe~y~p-benzoquinone-induced writhing test [J.
PharmacolExp.Therap., 125, 237 (1959) in mice.
Illustrative of the invention, ~-oxo-a-(phenylcarbamoyl)-~-(2-pyrrol-yl)-propionitrile of example 1 and ~-oxo-~-(4-chlorophenyl)-~-(2-pyrrollyl)-propionitrile of example 2 both at a dose of 100 mg/kg/p.o.
afford protection against carrageenin-induced edema in rats measured 3 hours after administration by 46 and 63% respectively. Similarly, ~-oxo-~-(2,4-difluorophenylcarbamoyl)-~-(2-pyrrolyl)-propionitrile of example 3 at a dose of 25 mg/kg/p.o. affords 33~ protection.

Furthermore the compounds of the invention, e.g. said above compounds of examples 1, 2 and 3 are active in the established adjuvant arthritis test in the rat at a dose of 25 mg/kg/p.o. (47%, 58% and 55~ protection respectively~.

Indicative of the immunopotentiating activity of the compounds of this invention, said compounds of examples 1 and 2 exhibit significant activity in the skin test in the BCG-immunized adjuvant arthritic rat at a dose of 25 mg/kg/p.o.

~L2~
-- S --The compounds of the invention are also aceive in the cartilage-synovium co-culture model of cartilage matrix degradation, indicati~e of cheir effectivenes~ in osteoarthritis. The screen is carried out as follow :

The proteogly~an matrix of bovine nasal septum cartilage i~ labelet in-vitro by incorporation of 35S into glycosaminoglycan. Cartilag~
slices are incubated overnight in a sulfate-free medi~lm containing _ S-sodiu~ sulfate. S-Labeled cartilage slices are co-culturet with normal synovium explant3 in multiwell tissue culture plate~.
After 4 day~ incubation a 100 ul aliquot of medium is counted.
Cartilag~ slices are hydrolyzed and a 100 ~1 aliquot of cartilage hydrolysate is counted. The percent S released into the mediu~ ic determinet ant the percent inhibition of matrix degradaeion i8 calculatet.

Illustraeive of the invention, ~-oxo--(phenylcarbamoyl)~ 2-pyrrol-yl)-propionitrile of example 1, ~-oxo-~-(4-chlorophenylcarbamoyl)-~-(2-pyrrolyl)-propionitrile of example 2 and ~-oxo-~-(2,4-difluoro-phenylcarbamoyl)-~-(2-pyrrolyl)-propionitrile of examplc 3 inhibit cartilage maerix degradation in vitro at a concentration range of about 10 ~ to 10 ~.

The afore~entioned advaneageou~ pro~erties render the compound~ of the invention useful as analgesic, antiinflammatory, antiarthritic and immunopotentiating agents especially in alleviation of pain, for the treatment and amelioration of e.g. inflammatory disorders, such as rheumatoid arthritis and osteroarthritis in mammals, including man.

Ihe c~mpounds of formula I are prepared according co conventional method~, for example, by a) conden~ing the compounds o~ ehe fonmulae III ant IV
Py-COC~2-C~ (III) and Ph-~C~O (IY~

~3L2~
g and, if desired, N-substituting a resulting compound with a reactive ester of ROH, wherein Py, Ph and R have meaning as previously defined; or b) removing the group Z from a compound of the formula V
CN R
Z - Py - CO - CH - CON- Ph (V) wherein Py, R and Ph have meaning as described above, and Z is a protecting group on the pyrrole nitrogen; or c) condensing a compound of formula VI
Py-COCH-COOH (VI) CN

or a reactive functional derivative thereof, with an amine of the formula R-NH-Ph (VII), wherein Py, R and Ph are as defined above; or d~ ring opening a compound of the formula VIII
R
py CON-Ph \. _ ./ (VIII) \N~ -wherein Py, R, Ph have meaning as described; or e) condensing a compound of formula IX or a reactive functional derivative thereof, with a compound of formula X
Py-COOH (IX) CH2-CO-N-Ph (X) CN R
wherein Py, R, Ph have meaning as described above;
f) reacting ammonia or salt thereof with a compound of formula XI
CIN Rl Y-CO-CH-CO-N-Ph (XI) ~22~9L4 wherein R and Ph have the meaning as described above, and Y represents unsubstituted or substituted 2,5-di-(loweralkoxy or halo)-2-tetra-hydrofuranyl; and, if desired, converting any resulting product of formula I into antother compound of the invention, and/or, if desired, converting any resulting enol into a lower alkyl enol ether or a lower alkanoyl enol ester, and/or, if desired, converting any-resulting-enol into a salt with a base, or a resulting enol salt into the free enol or into another salt with a base, and/or, if desired, resolving a mixture of isomers obtained into the single isomers The condensation according to process a) of the isocyanate of formula IV with the pyrroloylacetonitrile of formula III may be carried out according to U.S, patent 4,255,759, i.e., in the absence or presence of an inorganic or organic base, such as sodium hydride or triethyl-amine or in the presence or absence of a polar solvent, such as an ether, e.g. diethyl ether, ethylene glycol dimethyl ether (glyme) or tetrahydrofuran, and/or an amide or sulfoxide, e.g. dimethylformamide or dimethyl sulfoxide; preferably at a temperatu~e range of 25 to 100C; advantageously at elevated temperatures, e g at about 150 if no base is used~

The above-cited process a~ according to the invention is generally performed thus: said nitrile is treated with a slight molar excess of an anhydrous tri-lower alkylamine, preferably triethylamine, and then a molar equivalent of the appropriate phenyl isocyanate (Ph-N=C=0) is added, or a solution thereof in the polar solvents mentioned above, e.g. dimethylsulfoxide or glyme. After stirring for about 2-24 hours at room temperature, the reaction mixture is reduced in volume by evaporation without excessive warming. The residue is treated with an excess of dilute aqueous acid, e.g. 0.1-0.3 N hydro-chloric acid and the crude products are extracted or collected, washed with water, dried, triturated and/or recrystalli~ed from appropriate solvents, such as lower alkanols, alkanones, dialkyl ethers and/or alkyl alkanoates, e.g. methanol, acetone, diethyl ether and/or ethyl acetate.

The starting materials of formulae III and IV are either known or are prepared according to methods well-known to the art, e.g. for compounds of formula III as described in Ber. 113, 3675 (1980), Chem. Abstracts 29, 2164 and Ber. 55, 2390 (1922).

In the process b) a protecting group on the pyrrole nitrogen is for example optionally substituted benzyl, optionally substituted carbo-benzyloxy, lower alkanoyl (such as acetyl), trifluoroacetyl, di-lower alkylamino (such as dimethylamino), tetrahydropyranyl, lower alkyloxy-methyl (such as methoxymethyl), or lower alkoxycarbonyl (such as t-butyloxycarbonyl).

Process b) involving the removal of group Z is carried out by methods well-known to the art, e.g. 1) by hydrogellolysis when Z represents optionally substituted benzyl or carbobenzyloxy, e.g. with hydrogen in the presence of a hydrogenation catalyst; 2) by hydrolysis, preferably in the presence of e.g. a mineral acid or by ion exchange according to J. Am. Chem. Soc. 101, 6789 (1979), when Z represents optionally substituted carbobenzyloxy, lower alkanoyl, trifluoro-acetyl, lower alkoxycarbonyl, lower alkoxymethyl, or tetrahydro-pyranyl; 3) by oxidative cleavage, when Z represents dialkylamino, uith chromium (II) acetate according to J. Org. Chem. 46, 3760 (1981).

The starting materials of formula V are prepared by e.g. condensing an acid of formula XII, CN
Z-Py-CO-CH-COOH (XII) ~L2~

or a reactive functional derivative thereof, wherein Z and Py are as defined above, with an amine of the formula R-NH-Ph (VII).

The condensation is carried out according to U.S. patent No. 4,256,759 advantageously between room temperature and about 150, either with equivalent amounts of the reactants (when a reactive ester is used), or with an excess of the amine, or in the presence of another base, such as a tertiary amine, e.g. a tri-lower alkyl-amine or pyridine (when a halide or anhydride is used) in order to neutralize the generated acid~ The lower alkanol, generated in the reaction with said esters, is preferably distilled off together with a diluent, such as an aromatic hydrocarbon, e.g. benæene, toluene or xylene.
The condensation using a free carboxylic acid is preferably carried out in the presence of a condensing agent, e.g. a disubstituted carbodiimide, such as dicyclohexylcarbodiimide, l,l'-carbonyldi-imidazole or diethyl phosphorocyanidate (diethylphosphoryl cyanide).

Said starting materials of formula V may also be prepared according to other methods as described in U.S. patent 4,256,759.

The condensation of process c) is carried out similarly to methods described above for the preparation of compounds of formula V.

The starting materials of formula VI are prepared e.g. by reacting a compound of formula III with a derivative of carbonic acid, e.g.
ethyl chloroformate, to give e.g. the corresponding ethyl ester of a compound of formula VI, which in turn may be converted to a compound of formula VI, or another reactive functional derivative thereof, by conventional means.

The ring opening reaction according to process d), a reaction known to the art as described in J. Am. Chem. Soc. 35, 959 (1913), is carried out in the presence of strong inorganic or organic bases, ~22~2~.~

e.g. alkali metal hydroxides or tri-lower alkyl-aralkylammonium hydroxides, e.g. trimethylbenzylammonium hydroxide.

The isoxazole starting materials of formula VIII are also prepared by procedures well-known to the art, e.g. as disclosed in J. Am.
Chem. Soc. 35, 959 (1913).

The condensation according to process e), when the starting material is a reactive functional derivative of a compound of formula IX, is advantageously performed in the presence of metallizing agents such as alkali metals, metal alkoxides or hydrides, e.g. sodium hydride, potassium t-butoxide, thallous ethoxide, or under phase transfer conditions, in polar solvents e.g. 1,2-dimethoxyethane, dimethyl-formamide, dimethyl sulfoxide, attemperatures ranging from about 0 to 100, preferably at 25 to 50C.

Reactive functional derivatives of the carboxylic acids of formulae VI, IX and XII are for example anhydrides,especially mixed anhydrides, acid halides, the acid azide, lower alkyl esters and activated esters thereof, Mixed anhydrides are preferably such from pivalic acid, or a lower alkyl (ethyl, isobutyl) hemiester of carbonic acid; acid halides are for example chlorides or bromides; activated esters are for example succinimido, phthalimido or 4-nitrophenyl esters;
lower alkyl esters are for example the methyl or ethyl esters.

The condensation of a free carboxylic acid of formulae VI, IX and XII with a compound of formula VII or X, according to the above processes, may be carried out in the presence of a condensing agent, e.g. diethyl phosphorocyanidate, in the presence of a base, e.g.
triethylamine, in an inert polar solvent, e.g. dimethylformamide or methylene chloride.

~22~214 The reaction according to process f) preferably involves the reaction of ammonium acetate with a compound of formula XIa ~ CN R
H O CO-CH-CON-Ph (XIa) wherein R and Ph have the meaning as previously described above, X represents lower alkoxy or halogen, e.g. methoxy, ethoxy or chloro, advantegeously carried out in glacial acetic acid at elevated temperature, according to methodology well-known in the art, e.g.
as described in Acta Chimica Scandinavica 6, 862-~74 (1952).

The compounds of formula I, so obtained, can be converted into each other according to methods known per se. Thus, for example, resulting compounds (as enols) can be etherified, e.g. with lower dia~oalkanes, or esterified, e.g. with lower alkanoic anhydridesi or converted into salts with said pharmaceutically acceptable bases, e.g. an aqueous alkali metal hydroxide, advantageously in the presence of an ethereal or alcoholic solvent, such as a lower alkanol. From the solutions of the latter, the salts may be precipitated with said ethers, e.g.
diethyl ether or tetrahydrofuran, at moderate temperatures, e.g.
below 100C. Resulting salts may be converted into the free compounds by treatment with acids or bases. These or other salts can also be used for purification of the compounds obtained. In view of the close relationship between the free compounds and the compounds in the form of their salts, whenever a compound is referred to in this context, a corresponding salt is also intended provided such is possible or appropriate.

The starting materials used are known, or if new, can be prepared according to the methods known per se, for example as described in the references cited or as illustrated by the examples herein.

, ~2~

The above reactions are carried out according to standard methods, in the presence or absence of diluents, preferably such as are inert to the reagents and are solvents thereof, of catalysts, condensing or neutralization agents and/or inert atmospheres, at low temperatures, room temperature or elevated temperatures, at atmospheric or super-atmospheric pressure.

The invention also comprises any modification of the above processes, wherein a compound resulting as an intermediate at any stage thereof, is used as starting material and the remaining steps are carried out, or the process is discontinued at any stage thereof, or in which the starting material is formed under the reaction conditions or is used in the form of its salts or reactive derivatives, preferably alkali metal or trialkylammonium salts of said enols. In said processes of the invention those starting materials are advantageously selected, which yield the above-described preferred embodiments of the invention.

The invention also relates to novel intermediates and processes for their manufacture.

Depending on the choice of starting materials and methods, the new compounds may be in the form of one isomer, tautomer or mixtures thereof, provided such are possible.

The compounds, including their salts, can also be obtained in the form of their hydrates, or include other solvents used for the crystallization.

The pharmacolo~cally applicable compounds of the invention are useful in the manufacture of pharmaceutical compositions comprising an effective amount thereof in conjunction or admixture with excipients suitable for either enteral, parental or topical application. Pre-ferred are tablets and gelatin capsules comprising the active in-~22~L4 gredient together with diluents, e.g. lactose, dextrose, sucrose, mannitol, sorbitol, cellulose and/or glycine; and lubricants, e.g.
silica, talcum,stearic acid, its magnesium or calcium salt and/or polyethyleneglycol; for tablets also binders, e.g. magnesium aluminium silicate, starch paste, gelatin, tragacanth, methyl cellulose, sodium carboxymethyl cellulose and/or polyvinylpyrrolidone, if desired, disintegrants, e.g. starches, agar, alginic acid or its sodium salt, or effervescent mixtures; and/or adsorbents, colorants, flavors and sweeteners. Injectable compositions are preferably aqueous iso-tonic solutions or suspensions, and suppositories or topical lotions are advantageously made from fatty emulsions or suspensions. They may be sterilized and/or contain adjuvants, such as preserving, stabilizing, wetting or emulsifying agents, solution promoters, salts for regulating the osmotic pressure and/or buffers. Said pharma-ceutical compositions may also contain other therapeutically valuable substances. They are prepared according to conventional mixing, granulating or coating methods respectively and contain about 0.1 to 75%, preferably about 1 to 50%, of the active ingredient. A unit dosage for a mammal of about 50 to 70 kg may contain between about 10 to 200 mg of the active ingredient.

The following examples are intended to illustrate the invention and are not to be construed as being limitations thereon. Temperatures throughout are given in degrees Centigrade and all parts where given are parts by weight. If not otherwise stated, evaporations are carried out under reduced pressure, preferably between about 15 and 100 mm Hg.

Example 1: A solution of 3.1 g of 2-pyrroloylacetonitrile in 25 ml of glyme (ethylene glycol dimethyl ether) and 2.7 g of anhydrous triethylamine is treated with 3.0 g of phenyl isocyanate. After the moderately exothermic reaction, the mixture is let stand overnight.
Most of the solvent is evaporated and the residue is treated with

2~2~

water and 12 ml of 10~ sodium hydroxide solution. The aqeous, alkaline solution is washed with ethyl acetate and acidified with 6N hydro-chloric acid. The product is collected, washed with water, dried and recrystallized from ethanol, to give ~-oxo-~-(phenylcarbamoyl)-~-(2-pyrrolyl)-propionitrile, m.p. 207-209, the compound of formula II, wherein Rl to R4 are hydrogen.

The starting material is prepared as follows:
Into an ice-chilled solution of 30 g of pyrrole and 30 g of malono-nitrile in 800 ml of dry ether is passed dry hydrogen chloride for 20 minutes. After standing several hours the suspension is filtered to give 65 g of orange-brown, water-soluble solid. The solution of 50 g of this intermediate (the enamine nitrile hydrochloride) in 600 ml of water is covered with 400 ml of ethyl acetate and stirred for 22 hours at room temperature. The organic layer is separated, dried over magnesium sulfate and evaporated to give crystals, m.p.
77- 79; additional product is obtained by warming the aqueous layer on steam cone for 1/2 hour and extracting with ethyl acetate.
Recrystallization from water gives 2-pyrroloylacetonitrile, m.p.79-81.

Example 2: To the solution of 6.7 g of 2-pyrroloylacetonitrile in 25 ml of glyme and 5.5 g of triethylamine is added a solution of 8,6 g of 4-chlorophenyl isocyanate in 25 ml of glyme. After the exothermic reaction, the mixture is let stand overnight. Part of the solvent is evaporated and the cooled residue is poured into a solution of 10 ml of 6N hydrochloric acid in 250 ml of water. After the addition of some methanol, the crude material is collected. It is dissolved in dilute sodium hydroxide solution, the solution is treated with charcoal, filtered, and acidified with 6N hydrochloric acid.
The reprecipitated product is collected, washed with water, and triturated with methanol to give solid, m.p. 219-221D. Recrystalliza-tion from methanol gives ~-oxo-~-(4-chlorophenylcarbamoyl)-~-(2-pyrrolyl)-propionitrile, m.p. 223-225.

~LZ2C3Z9L~L

Example 3: Reaction of 2.4 g of 2-pyrroloylacetonitrile with 3.1 g of 2,4-difluorophenyl isocyanate in the presence of 2.0 g triethyl-amine in 25 ml of glylne and isolation simularly to the preceding examples, followed by trituration with and recrystallization from ethanol gives ~-oxo-a-(2,4-difluorophenylcarbamoyl)-~-(2-pyrrolyl)-propionitrile, m.p. 169-171.

Exam? le 4: Reaction of 2.0 g of 2-pyrroloylacetonitrile with 3.0 g of 3-(trifluoromethyl)-phenyl isocyanate in the presence of 1.8 g of triethylamine in 25 ml of glyme similarly to the previous examples and recrystallization of the crude product from methanol gives ~-oxo-~-(3-trifluoromethylphenylcarbamoyl)-~-(2-pyrrolyl)-propioni-trile, m.p. 210-212.

Example 5: Reaction of 2.4 g of 2-pyrroloylacetonitrile with 2.5 g of 4-fluorophenyl isocyanate in the presence of 2.2 g of triethyl-amine in 25 ml of glyme, similarly to preceding examples, reprecipita-tion from dilute sodium hydroxide solution with hydrochloric acid, and recrystallization from methanol, gives ~-oxo--(4-fluorophenyl-carbamoyl)-~-(2-~7rro~yl)-propionitrile~ m.p. 233-234.

Example 6: Reaction of 2.7 g of 2-pyrroloylacetonitrile with 3.8 g of 3-chloro-4-fluorophenyl isocyanate in the presence of 2.4 g of triethylamine in 25 ml of glyme and workup similarly to the preceding examples gives after recrystallization from ethyl acetate, ~-oxo-~-(3-chloro-4-fluorophenylcarbamoyl)-~-(2-pyrrolyl)-propionitrile, m~p~ 257-258 (decomposition).

Example 7: A solution of 2.1 g of 2-pyrroloylacetonitrile in 15 ml of glyme and 1~8 g of triethylamine is treated with a solution of

3 g of 2,4-dichlorophenyl isocyanate in 15 ml of glyme similarly to the preceding examples. Mildly exothermic reaction results in forma-tion of a thick suspension of crystals. After standing overnight, ~ 19 -dilution with dry ether and filtration gives the triethylanur,or.ium salt of ~-oxo-cl-(2~4-dichlorophenylcarbamoyl)--~-(2-pyrrolyl~-pro-pionitrile, m.p. 180-182 (decomposition), in form of the enol structure as represented by formula Ia, wherein Py is 2-pyrrolyl, R is hydrogen and Ph is 2,4-dichlorophenyl.
A solution of the above triethylammonium salt in methanol is added to a solution of 4 ml of 6N hydrochloric acid in 250 ml of water.
The free enolic product is collected, washed with water and triturated with methanol to give crystals, m.p. 219-221. Recrystallization from ethyl acetate gives ~-oxo-~-(2,4-dichlorophenylcarbamoyl)-~-(2-pyrrolyl)-propionitrile, m.p. 222-223.

Example 8: A mixture of 1.1 g of ~-oxo-~-ethoxycarbonyl-13-2--(pyrrolyl)-propionitrile, 1.5 g of 4-fluoroaniline and 60 ml of xylene,is refluxed for 42 hours. After standing and cooling to room temperature overnight, the solution is filtered, evaporated and the residue is purified to yield ~-oxo-~-(4-fluorophenylcarbamoyl)-~-(2-pyrrolyl)-propionitrile of example 5.

Th~: starting ma~erial is prepared as follows:
a) A solutlon of 2.22 g of 2-pyrrolecarboxylic acid, 8.4 ml of anhydrous triethylamine and 2.1 ml of ethyl cyanoacetate in a sufficient amount of dimethylformamide so as to obtain a solution, is stirred, treal:ed with 2.g ml of diethyl phosphorocyanidate at room temperature, and allowed to stand for 1.3 hours. The solution is cooled in arl ice-bath, treated with 50 ml of water, filtere-l and acidified with 6N hydrochloric acid. The resulting precipitate is collected, washed with water, dried and recrystallized from ether to give ~-oxo-~-ethoxycarbonyl-,~-(2-pyrrolyl)-propionitrile, m.p.
138-139.

12213;2~

b) 2-Pyrroloylacetonitrile is treated in the presence of triethyl-amine in ethylene glycol dimethel ether at 50D overnight with ethyl chloroformate, and the product is purified to give ~-oxo-~-ethoxy-carbonyl-~-(2-pyrrolyl)-propionitrile.

Example 9: By procedures analogous to those described in the preceding examples the followingcompounds of formula I can be prepared.

No. Py R Ph .. . ~
9/1 2-pyrrolyl H 4-methoxyphenyl 9/2 2-pyrrolyl H 4-methylthiophenyl 9/3 2-pyrrolyl H 4-hydroxyphenyl 9/4 2,5-dimethyl-3 pyrrolyl H 4-chlorophenyl 9/5 3,5-dimethyl-2-pyrrolyl H 2,4-difluorophenyl 9~6 3,5-dimethyl-4-carbo- H 4-chlorophenyl ethoxy-2-pyrrolyl 9/7 2-pyrrolyl H 4-trifluoromethylphenyl 9~8 2-pyrrolyl H 4-tolyl 9/9 2-pyrrolyl CH3 phenyl The pyrrole stzrting materials for examples 9/4, 9/5 and 9/6 are described in Ber. 113, 3675 (1980), Chem. Abstr. 29, 2164, and Ber~ 55, 2390 (1922) respectively.

Example 10: Treatment of ~-oxo-~-(2-phenylcarbamoyl)-~-(2-pyrrolyl)-propionitrile with an equivalent amount of a concentrated aqueous or alcoholic solution of sodium, potassium or calcium hydroxide or ethoxide and evaporating to dryness, yields the corresponding sodium, potassium or calcium salt of the compound in tautomeric form of formula Ia, wherein Py is 2-pyrrolyl, Ph is phenyl and R is hydrogen.

O~

Similarly prepared with an equivalent amount of triethylamine or tri-(hydroxyethyl)-amine are the triethylammonium and tris-(hydroxy-ethyl)-ammonium salts respectively.

Example 11: To 500 ml of ethereal diazomethane, generated from 10.3 g of N-nitroso-N-methylurea with 35 ml of 45~ aqueous potassium hydroxide and dried over potassium hydroxide pellets, are added 3.9 g of ~-oxo-~-(phenylcarbamoyl)-~-(2-pyrrolyl)-propionitrile.
After the nitrogen evolution ceases, the solution is Eiltered and evaporated~ Purification yields the corresponding methyl enol ether, i.e. the ~-methoxy-~-(phenylcarbamoyl)-~-(2-pyrrolyl)-acrylonitrile.

Example 12: To the solution of 1.6 g of cyanoacetanilide in 10 ml of dimethylformamide is added 3.4 g of potassium t-butoxide. The stirred, cooled suspension is treated with 1.1 g of pyrrole-2-carboxylic acid in 6 ml of dimethylformamide and 1.4 ml of diethyl phosphorocyanidate (DEPC). The deep-red solution is stoppered and allowed to react for 1/2 hour. The reaction mixture is treated with 80 ml of ice-cold water, and filtered to remove unreacted cyano-acetanilide and acidiEied with 6N hydrochloric acid. The resulting precipitate is collected, washed with water and dried. The crude product is dissolved in ethyl acetate, the ethyl acetate solution is filtered and evaporated to dryness. The resulting product is re-crystallized from ethanol-ether to yield ~-oxo-~-(phenylcarbamoyl)-~-(2-pyrrolyl)-propionitrile identical to the product of example 1.

Example 13: Protection in the established adjuvant athritistest at a ~
dose of 25 mg/kg/p.o. essentially accordingto Proc. Soc. Exp. Biol. Med.
137, 506 ~1971).

3L;~26~

Example % change from control 1 47%
2 -58%
3 -55%

4 -59%
-59%
7 -42%

Example 14: Preparation of 1.000 capsules each containing 25 mg of the active ingredient:

Formula:
~-Oxo-~-(4-fluorophenylcarbamoyl)-~-(2-pyrrolyl)-propionitrile 25.0 g Lactose 207.0 g Modified starch 80.0 g Magnesium stearate 3.0 g Procedure:
All the powders are passed through a screen with openings of 0.6 mm.
Then the drug substance is placed in a suitable mixer and mixed first with the magnesium stearate, then with the lactose and starch until homogeneous. No. 2 hard gelatin capsules are filled with 315 mg of said mixture each, using a capsule filling machine.
Analogously capsules are prepared, containing 10-200 mg of the other compounds disclosed and illustrated herein.

Example 15: Preparation of 10.000 tablets each containing 100 mg of the active ingredient:

Formula:
~-Oxo-~-(2,4-difluorophenylcarbamoyl)- 1 000 00 ~-(2-pyrrolyl)-propionitrile Lactose 2.535.00 g Corn starch 125.00 g Polyethylene glycol 6.000 150.00 g Talcum powder 150.00 g Magnesium stearate 40.00 g Purified water q.s Procedure_ All the powders are passed through a screen with openings of 0.6 mm.
Then the drug substance, lactose, talcum, magnesium stearate and half of the starch are mixed in a suitable mixer. The other half of the starch is suspended in 65 ml of water and the suspension added to the boiling solution of the polyethylene glycol in 260 ml of water~ The paste formed is added to the powders, which are granulated, if necessary, with an additional amount of water. The granulate is dried overnight at 35, broken on a screen with 1.2 mm openings and compressed into tablets, using concave punches uppers bisected.

Analogously tablets are prepared, containing 10-200 mg of one of the other compounds illustrated by the previous examples.

Example 16: The analgesic activity (antinociceptive activity) is measured by the method of Hendershot and Forsaith: J. Pharmacol. Exp.
Therap. 125, 237, 1959 as modified and described below:

Mice previously fasted overnight are treated orally with the test compound dissolved in 0.75 % methylcellulose at doses of 1 to 50 mg/kg, or with the vehicle alone, 55 minutes before the induction of the writing syndrome by i.p. injection of 0.25 ml of a suspension of phenyl-p-benzoquinone (0.03 %) in tragacanth (0.4 %).

~5L22C~

Starting 5 minutes thereafter, the number of writing movements provoked by the irritant are counted over an observation period of 10 minutes. The antinociceptive ED50 of the test compound is the dose which reduces the mean frequency of writing movements by 50 % in comparison to the controls.

Claims (18)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. Process for the manufacture of a compound of the general formula I or a tautomer thereof (I) wherein Py is 2- or 3-pyrrolyl unsubstituted at the 1-position and at one or more of the remaining three positions is either unsubstituted or substituted by one or more substitutents chosen from lower alkyl, carboxy, lower carbalkoxy, and halogen; R is hydrogen or lower alkyl; and Ph is phenyl, unsubstituted or substituted by one to three identical or different members selected from lower alkyl, lower alkoxy, lower alkylthio, lower alkylsulfinyl, lower alkylsulfonyl, hydroxy, halogen, trifluoromethyl, nitro, amino and lower alkanoylamino; the lower alkyl enol ethers thereof; or the lower alkanoyl enol esters thereof, or salts including pharmaceutically acceptable salts thereof, which process com-prises:
(a) condensing the compounds of the formulae III and IV
Py-COCH2-CN (III) and Ph-N=C=O (IV) in the absence or presence of an inorganic or organic base, and, if desired, N-substituting a resulting compound with a lower alkyl ester of ROH, wherein Py, Ph and R have as previously defined; or (b) removing the group Z from a compound of the formula V

(v) wherein Py, R and Ph have meaning as described above, and Z is a protecting group on the pyrrole nitrogen (c) condensing a compound of formula VI

(VI) or a reactive functional derivative thereof with an amine of the formula R-NH-Ph (VII), wherein Py, R and Ph are as defined above; in the absence or in presence of a diluent, (d) ring opening a compound of the formula VIII

(VIII ) wherein Py, R and Ph have meaning as described; in the presence of strong inor-ganic or organic bases, (e) condensing a compound of formula IX or a reactive functional deriva-tive thereof with a compound of formula X
Py-COOH (IX) (X) wherein Py, R,Ph have meaning as described above; in the presence of a condens-ing agent or of a base, or (f) reacting ammonia or salt thereof with a compound of formula XI

(XI) wherein R and Ph have the meaning as described above, and Y represents 2,5-di-(loweralkoxy or halo)-2-tetra-hydrofuranyl; in the presence of glacial acetic acid at elevated temperature and, (g) if desired, converting any resulting product of formula I into another compound of the invention, and/or, if desired, converting any resulting enol into a lower alkyl enol ether or a lower alkanoyl enol ester, and/or, if desired, converting any resulting enol into a salt with a base, or a resulting enol salt into the free enol or into another salt with a base, and/or, if desired, resolving a mixture of isomers obtained into the single isomers.

2. Process according to claim 1, wherein Py represents the group wherein each of R1 and R2 is hydrogen or lower alkyl; and Ph represents the group R3 and R4 is hydrogen, lower alkyl, lower alkoxy, hydroxy, halogen or tri-fluoromethyl, to provide a compound of the formula II

(II)

3. Process according to claim 2, wherein R1 and R2 are hydrogen; each of R3 and R4 is hydrogen, alkyl with up to 4 carbon atoms, fluoro, chloro or trifluoromethyl.

4. Process according to claim 2, wherein each of R1 and R2 is hydrogen;
and each of R3 and R4 is hydrogen, methyl, methoxy, fluoro, chloro or tri-fluoromethyl.

5. Process for the manufacture of .beta.-Oxa-.alpha.-(4-chlorophenylcarbamoyl)-(2-pyrrolyl)-propionitrile, which consists in condensing the compounds of the formulae III and IV
Py-COCH2-CN (III) and Ph-N=C=O (IV) in which the Py is 2-pyrrolyl and Ph is 4-chlorophenyl in the presence of tri-ethylamine and recovering the desired compound.

6. Process for the manufacture of .beta.-Oxa-.alpha.-(2,4-difluorophenylcarbamoyl)-.beta.-(2-pyrrolyl)-propionitrile, which consist in condensing the compounds of the formulae III and IV
Py-COCH2-CN (III) and Ph-N=C=O (IV) in which the Py is 2-pyrrolyl and Ph is 2,4-difluorophenyl, in the presence of triethylamine and recovering the desired compound.

7. Process for the manufacture of .beta.-Oxa-.alpha.-(3-trifluoromethylphenyl-carbamoyl)-.beta.-t2-pyrrolyl)-propionitrile, which consists in condensing the com-pounds of the formula III and IV

Py-COCH2-CN (III) and Ph-N=C=O (IV) in which Py is 2-pyrrolyl and Ph is 3-trifluoromethylphenyl, in the presence of triethylamine and recovering the desired compound.

8. Process for the manufacture of .beta.-Oxa-.alpha.-(4-fluorophenylcarbamoyl)-.beta.-(2-pyrrolyl)-propionitrile, which consists in condensing the compounds of the formula III and IV
Py-COCH2-CN (III) and Ph-N=C=O (IV) in which the Py is 2-pyrrolyl and Ph is 4-fluorophenyl in the presence of tri-ethylamine; or b)condensing a compound of formula VI with VII

(VI) and R-NH-Ph (VII) in which Py is 2-pyrrolyl, R is hydrogen and Ph is 4-fluorophenyl, and recovering the desired compound.

9. Process for the manufacture of .beta.-Oxa-.alpha.-(3-chloro-4-fluorophenyl-carbamoyl)-.beta.-(2-pyrrolyl)-propionitrile, which consist in condensing the com-pounds of the formulae III and IV
Py-COCH2-CN (III) and Ph-N=C=O (IV) in which the Py is 2-pyrrolyl and Ph is 3-chloro-4-fluorophenyl in the presence of triethylamine, and recovering the desired compound.

10. -Process for the manufacture of .beta.-Oxa-.alpha.-(2,4-dichlorophenylcarba-moyl)-.beta.-(2-pyrrolyl)-propionitrile, which consist in a) condensing the compounds of the formulae III and IV
Py-COCH2-CN (III) and PH-N=C=O (IV) in which Py is 2-pyrrolyl and Ph is 2,4-dichlorophenyl, in the presence of triethylamine and recovering the desired compound.

11. A compound of the formula I shown in claim 1, in which formula all the symbols have the meanings given in claim 1, these compounds in their enol form, a lower alkyl enol ether or a lower alkanoyl enol ester, or a pharmaceu-tically acceptable salt thereof, or the tautomeric form of such a compound, whenever prepared by the process of claim 1 or by an obvious chemical equiva-lent thereof.

12. .beta.-Oxa-.alpha.-(4-chlorophenylcarbamoyl)-.beta.-(2-pyrrolyl)-propionitrile or a pharmaceutically acceptable salt thereof, whenever prepared by the process of claim 5 or an obvious chemical equivalent thereof.

13. Process according to claim 1(a) wherein the base is chosen from sodium hydride and triethylamine.

14. Process according to claim 1(b) wherein the protecting group on the pyrrole nitrogen is chosen from benzyl, substituted benzyl, carbobenzyloxy, lower alkanoyl, trifluoroacetyl, di-lower alkylamino, tetrahydropyranyl, lower alkyl oxy or lower alkoxy carbonyl.

15. Process according to claim 1(c) wherein the reactive functional derivative is the acid anhydride and the diluent is an aromatic hydrocarbon.

16. Process according to claim 1(d) wherein the base is an alkali metal hydroxide.

17. Process according to claim 1(e) wherein the reactive derivative is the carboxylic acid anhydride.

18. Process according to claim 1 wherein a prepared salt is chosen from the salts of a compound of formula I with sodium, potassium, calcium, triethyl-ammonium or tris-(hydroxyehtyl)ammonium.