DERIVATIVES OF THE 3-MERCAPTO-2-OXO-1-PYRROLIDINACETIC ACID, PROCESS FOR THEIR PREPARATION AND PHARMACEUTICAL COMPOSITIONS CONTAINING THEM

Abstract: The invention relates to the 3-mercapto-2-oxo-1-pyrroli­ dinyl acetic acid and its derivatives, endowed with mucolithic, expectorant, anti-cough activities; to a process for their prepa­ ration by treatment of the related 3-bromoderivatives with the corresponding thiol and to the pharmaceutical preparations containing these compounds as active principle.

Description: SPECIFICATION The present invention relates according to one of its features, to compounds having the formula I: EMI1.1 wherein R is hydrogen, -CO2, -OH COOR3, in which R is a C -C linear or branched -CO2, 2 3 2 1 8 chain alkyl, or a substituted or unsubstituted phenyl, a heterocyclic radical containing 1, 2 or 3 hetero atoms from among sulphur, nitrogen, oxygen, such as 2thenoyl, 2-furyl, 4-thiazolil, 1,3,4-thiazolyl-2-yl groups and in which R3 is hydrogen, a linear or branched chain C -C alkyl and R is hydrogen or a linear or branched chain 14 1 C1-C8 alkyl and to the pharmaceutically acceptable salts of the compounds of formula I wherein one or both the substituents R and R1 are hydrogen; in fact, when R and/or R1 and/or R3 are hydrogen, the -SH and -COOH groups can be salified with an inorganic or organic pharmaceutically acceptable base. Preferred salts are those with alkyl metals, such as sodium and potassium, with earth-alkaly metals such as magnesium and calcium, with organic bases, such as diethanolamine, tromethamine or with amphoteric products such as lysine or arginine. According to another feature, the present invention relates to a process for the preparation of the compounds of formula I and, possibly, of their salts with inorganic or organic bases, characterized in that a bromopyrrolidin9sne derivative of formula II: EMI1.2 wherein R1 has the above definite meaning, is treated with a thiolic compound of formula III: HS- R (III) wherein R has the above definite meaning, or with an alkali salt thereof, possibly in the presence of an inorganic or organic base in an organic solvent at a temperature of between 0tC + 400C and the thus obtained product is then possibly converted into its pharmaceutically acceptable salts. The starting compounds of formula II are known in the literature and may be prepared by reacting 2,4-dibromobutiryl bromide with glycine ethylester and subsequent cyclization of the N-(2,4-dibronobutiryl)glycine ethylester with sodium methoxide with- methanol (II Pharmaco, Ed. sci. 1978, 33, 130-141). The thiolic compounds of formula III are well known and may be used in acidic form or as one of their alkali salts, preferably sodium or potassium salts. In the case of the preparation of the compounds of formula I wherein R is hydrogen, it is suitable to use an alkali sulfidride, preferably NaSH or KSH. When the reaction is carried out in the presence of an organic or inorganic base, the latter may be an alkali hydroxide or carbonate, or an organic base such as triethylamine. The reaction is as a rule completed after 2-8 hours at a temperature of between oec and + 400C and the final product is isolated according to the standard methods and possibly salified by treatment with an inorganic or organic base. The process for the preparation of the compounds of formula I is a wholly general method. However the possible simultaneous presence of an acid and of an ester, of a free sulfidryl group or of thioesters, leads to variations of the general method which may result in increased yield. For instance, in the case of the preparation of compounds of formula I in which R is hydrogen, it may be suitable to have recourse in a first time to the preparation of the corresponding S4enzoyl derivative (formula I, R= CO-C H ) and to the subsequent 65 removal of the benzoyl group. It may also by convenient to have recourse to the S-benzoylderivative, which is obtained with high yields from the starting compounds of the formula II, in the preparation of less reactive thioesters, which can be readily obtained, after removal of the benzoyl group, by reaction with the chloride of the suitable acid. The above variations are illustrated by the scheme of preparation of the compounds of formula IV wherein R1=H and R= CH2-COOH, of formula V wherein R=R1=H and 2 of formula VI wherein R = H and R= 2-thenoyl. EMI3.1 according to the following preferred method: a- hydrolysis of the ethyl ester of 3-bromo-2-1-pyrrolidinyl acetic acid (IIa) in alcohol solution in the presence of a calculated amount of N NaOH water solution and subsequent acidification to give the corresponding acid (IIb). b- reaction of the acid Ilb with potassium thiobenzoate in aqueous solution to give 3 thiobenzoyl-2-oxo-1-pyrrolidinyl acetic acid (VII). c- removal of the benzoyl group in aqueous solution of ammonium hydroxide to give the compound V. d- esterification of V, as sodium salt, with the chloride of 2-thiophen-carboxilyc acid to give the compound VI. e- reaction of Ub with thioglycolic acid HS-CH2COOH, to give the compound IV. The hydrolysis a) is preferably carried out in a reaction medium from the group formed by water, ethanol, methylcellosolve, dimethylsulfoxide, EMI3.2 ethylene glycol, dioxane or their mixtures. The suitable temperature is of between OOC and + 500C; the reaction time varies with the temperature. At + 200C the hydrolysis reaction in aqueous ethanol is completed after 4-5 hours. The isolation of the product Ilb takes place by neutralization with diluted Howl, subsequent concentration and extraction of the residue with a suitable solvent, for instance ethyl acetate. From the organic phase the product is isolated by evaporation under reduced pressure. The reaction b) to give VII is carried out in water solution wherein the compound 110, as the sodium salt , is contacted with potassium thiobenzoate. At temperatures of between + 100 and + 500C, preferably at + 200/+250C a time of 5 hours is required for the completion of the reaction. After acidification the product is extracted with a suitable solvent, for instance ethyl acetate. From the organic phase the product is isolated by concentration under vacuum. The removal of the benzoyl group (reaction c) to give the compound V is carried out in aqueous environnment by addition of an alkali hydrate , preferably ammonium hydroxide. At temperatures of between + 100C and + 500C, preferably at +150C/+200C the reaction is completed after 5 hours. After removal of the benzamide by filtration, the aqueous solution is evaporated under vacuum at + 500C and the residue, after acidification is extracted with a suitable solvent, for instance ethyl acetate, and subsequently the product V is isolated by concentration under reduced pressure of the organic phase. The preparation of the compound of formula VI (reaction d) is carried out by acylation of the thiol V, as the sodium salt, with reactive derivatives of the 2-thiophencarboxylic acid; as reactive derivatives, acidic chloride or the mixed anhydrides are meant and the reaction conditions are the standard ones. The obtention of the compound of formula IV (reaction e) takes place by reacting the bromoderivative Ilb with thioglycolic acid in anhydrous environnment in a suitable solvent, for example N,N-dimethylformamide, in the presence of a base as acceptor of hydrogen bromide, for example, triethylamine. The reaction takes place quickly + 200/+250C and requires for the completion 4 hours. The isolation of the compound IV takes place by diluting the reaction mass with water and subsequently acidificating to pH 2, whereby a crystalline product is obtained, which is filtered and then recrystallized. The 3-mercapto-2-oxo-lpyrrolidinyl acetic acid (V) and its derivatives are endowed with interesting phamacological properties; particularly they are endowed with a relevant mucolithic, expectorant and anticough activity and moreover show a very low toxicity. More specifically in the test of mucolithic activity "in vitro", with a 4% mucin suspension (II Pharmaco, ed. prat. 1978, 33, 379-391) and the molar concentration being the same (0,012 M), the 3-mercapto-2-oxo-1-pyrrolidinyl acetic acid (V), the 3-(2-thenoylthio)-2-oxo-lpyrrolidinyl acetic acid (VI) and 3Zenzoylthio- 2-oxo-lgyrrolidinyl acetic acid (VII), (the last two ones after a suitable hydrolis), caused a viscosity reduction respectively of 20.95%, 18.22% and 16.13%, which are significantly higher than that of N-acetyl-L-cysteine under the same experimental conditions (12.699Cj. Furthermore the compounds of the present invention show a relevant expectorant activity, which is demonstrated in the test of fluorescein elimination in the fluid of the respiratory tract (II Pharmaco, ed. prat. 1981, 36, 167-172); in this test, two representative compounds, 3-mercapto-2-oxo-1-pyrrolidinyl acetic acid (V) and 3-(2 thenoylthio)-2-oxo-1-pyrrolidinyl acetic acid (VI) demonstrated, in comparison to the controls, increases of escretion of the colouring matter respectively of 52.92% and 54.26%, which are significantly higher than that of N-acetyl-L-cysteine at the same dose (1 mM/kg/os) and under the same experimental conditions (29.63%). The anticough activity of the compounds of the present invention was assessed in the test of the cough iinduced by citric acid in the guineapig (Screening methods in pharmacology of R.A. Turner -Acad. Press 1965, 219) wherein two representative compounds, 3-mercapto-2-oxo-lpyrrolidinyl acetic acid (V) and 3-(2-thenoylthio)2 oxo-1-pyrrolidinyl acetic acid (VI) did show with respect to the controls a reduction of the cough respectively equal to 74% and 68.50% at the dose of 1 mM/kg/i.p. which are not significantly different from that obtained with codeine phosphate at the dose of 5 mg/kg i.p. (87.00%). The compounds of the present invention have a very low acute toxicity; two representative compounds, 3-mercapto-2oxoAyrrolidinyl acetic acid (V) and 3-(2 thenoyfthio)-2-oxo-lpyrrolidinyl acetic acid (VI) show in the male and the female mouse a LD50 value by i.p. route higher than 2000 mg/kg and a LD value by oral 50 route higher than 3000 mg/kg and in the male and female rat a LD50 value by i.p. route higher than 1500 mgtkg and a LD50 value by oral route higher than 5000 mg/kg. Thanks to their pharmacological properties and to the absence of toxicity, the compounds of formula I and their possible pharmaceutically acceptable salts may be used as drugs in the treatment of diseases of the respiratory tract. Thus, the present invention relates, according to a further feature, to pharmaceutical compositions containing, as the active ingredients, the compounds of formula I or their possible pharmaceutically acceptable salts. The pharmaceutical compositions of the present invention contain the active ingredients, both alone and in admixture with pharmaceutical vehicles or excipients, in pharmaceutical forms and in dosing units suitable for the administration by oral, parenteral, rectal or in halating route, such as tablets, powders, granules, capsules, solutions, suspensions, syrups or suppositories. Each dosing unit contains from 50 to 500 mg of active ingredient and is administered so as to give to the patient a daily dose of active substance varying from 100 to 2000 mg in the treatment of diseases of the respiratory organs, particularly bronchities, tracheobronchities, pharyngitis, rhinopharyngitis. The compositions of the present invention may contain, besides the compounds of formula I or their possible salts, other active substances, such as for instance antibiotics, bronchodilating compounds, balsamic compounds, anti-inflammatory compounds, anti-hystaminic compounds or local anaesthetic compounds. The following, non limitating, examples, illustrate the invention. EXAMPLE 1 A solution of 180 g (0.72 moles) of ethyl 3-bromo-2-oxo-1-pyrrolidinyl acetate in 450 ml of 95% ethyl alcohol is added, at + 150/+200C and over 20 minutes, with 810 ml of a N solution of sodium hydroxide. The mixture is stirred for 4 hours at + 150/+200C, then neutralized with the equivalent amount of 3 N hydrogen chloride. The solution is evaporated under reduced pressure at + 350C until a dense syrupy mass is obtained, which is dispersed with 900 ml of ethyl acetate. The mixture is made acidic to pH 3.5 with 6N hydrogen chloride, the temperature being maintained at + 150C/+200C. The organic phase is separated, and is collected, whereas the aqueous one is extracted after saturation with sodium chloride by means of further 600 ml of ethyl acetate. The combined ethyl acetate phases are dried on anhydrous sodium sulphate, decoloured with charcoal and stirred for 30 minutues. After filtration, the solution is evaporated under vacuum at + 350C until a white solid residue is obtained. The raw product (1109) is crytallized with 380 ml of anhydrous ethyl alcohol. There are obtained: 98.5 g (55%) of 3-bromo-2-oxo-lpyrrolidinyl acetic acid; m.p. 1550-1580C. Analitical data for C H BrNO (MW 250.104) 3 calculated % : C 28.81 - H 3.22 - N 5.60- 8r 31.95 found %: C 28.77 - F1 3.19 - N 5.62 - Br 31.79 The IR (KBr) and NMR (DMSO-d ) spectra agree with the foreseen structure. 6 EXAMPLE 2 A solution of 29.4 g (0.35 moles) of sodium bicarbonate in 215 ml of water is added with 77.7 g (0.35 moles) of 3bromo-2-oxo-1-pyrrolidinyl acetic acid; separately a solution of potassium thiobenzoate is prepared from 53.6 g (0.388 moles) of thiobenzoic acid, 33.78 g (0.244 moles) of potassium carbonate and 357 ml of water. The latter solution is added to the former one under nitrogen stream over 30 minutes, and then the mixture is stirred for 5 hours at + 200C/+250C (pH about 8). Then 800 ml of ethyl acetate are added and the mixture is brought to pH 2 with 6 N hydrogen chloride; the organic phase is separated and the aqueous one is extracted with further 400 ml of ethyl acetate. The combined organic extracts are dried over anhydrous sodium sulphate; after removal of the drying compound by filtration, the solid residue is obtained by evaporation under reduced pressure. The raw product is crystallized with 370 ml ethyl acetate to give: 76 g (77%) of 3-benzoylthio-2-oxo-1-pyrrolidinyl acetic acid; m.p. 1200-1220C. Analitical data for C13H13NO4S S (MW 279.318) Calculated %: C 55.90 - H 4.69 - N 5.015 - S 11.48 found % : C 56.03 - H 4.66 - N 4,99 - S 11.50 A solution of 70 g (0.25 moles) of the thus obtained product in 110 ml of ethyl acetate, heated to 600/650C, is added with 250 ml of a solution of 1 M sodium 2ethylhexanoate in ethyl acetate. After 30 minutes of stirring it is cooled to + 50C , filtered and washed with ethyl acetate (100 ml). There are obtained: 65 g (86%) of crystalline white sodium 3-benzoylthio-2-oxo-1pyrrolidinyl acetate; m.p. 195-198 C. EXAMPLE 3 50 g (0.166 moles) of sodium 3benzoylthio-2-oxo-1-pyrrolidinyl acetate are suspended in 220 ml of water at + 150C/+200C; under stirring there are added over 15 minutes 115 ml of a water solution of ammonium hydroxide 280 Bè and a clear solution is obtained. It is maintained under stirring for 5 hours at + 150/+200C, then it is cooled at + 5 C and the crystalline product is filtered, it being formed by benzamide (16.2 g - 80% of the theoretical value). The filtrate is evaporated under vacuum at 50 C until a dense syrupy mass is obtained which is diluted with 80 ml of water and extracted with 200 + 100 ml of ethyl acetate to remove the benzamide still dissolved. The aqueous phase is added with 300 ml of ethyl acetate and brought to pH 3 by addition of 37% hydrogen chloride; the organic phase is separated and the aqueous one is extracted with 200 + 100 ml of ethyl acetate The combined organic phases are dried over anhydrous sodium suphate and evaporated under vacuum. There are thus obtained:20.7 g (71%) of 3-mercapto-2-oxo-1-pyrrolidinyl acetic acid as a clear oil which solidificates completely: m.p. 78-810C. Analitical data for C H NO S (MW 175.209) 69 3 Calculated %: C 41.13 - H 5.17 - N 7.99 - S 18.30 found % : C 41.21 - H 5.12 - N 7.98 - S 18.34 The IR (K8r) and NMR (0001) spectra agree with the foreseen structure. 3 To a solution of 20 g (0.114 moles) of 3-mercapto-2-oxo-1-pyrrolidinyl acetic acid in 100 ml of ethyl acetate, heated to 500C, 115 ml are added of a solution of 1M sodium 2-ethylhexanoate in ethyl acetate. After 15 hours at + 50C, it is filtered and washed with ethyl acetate (30 ml). There are thus obtained: 17.5 g (78%) of white crystalline sodium 1-carboxymethyl-2oxo-3-pyrrolidinyl thiolate; m.p. 210-2150C. EXAMPLE 4 A solution of 50 g (0.25 moles) of the sodium salt obtained in the example 3 in 260 ml of water is added with 78.7 g( 0.57 moles) of potassium carbonate. It is cooled at +5 C, 36 g (0.31 moles) of chloride of 2-thiophencarboxylic acid are added, and the temperature is them allowed to raise to + 1500 over 15 minutes. The reaction mass is poured in a mixture comprising 700 ml of methylene chloride and 350 ml of ethyl acetate , then brought to pH 2 by addition of 20% sulphuric acid, the temperature being maintained at + 1501+2000. The aqueous phase is separated and extracted with 500 ml of ethyl acetate/methylene chloride (1:2). The organic phases are dehydrated over anhydrous magnesium sulphate, concentrated under reduced pressure until a vblume of 250 ml is obtained; after dilution with 300 ml of ethyl acetate, it is concentrated again under reduced pressure to 200 ml. It is crystallized at + 50C for 24 hours, then filtered, washed with ethyl acetate (150 ml) and dried under reduced pressure at 350C. There are thus obtained : 45.8 g (64%) of 3-(2-thenoyl)-2-oxo-1-pyrrolidinyl acetic acid; m.p. 141-143oC. Analitical data for 011H11NO4S2 (MW 285.344) Calculated % : C 46.30 - H 3.88 - N 4.90 - S 22.47 found % : C 45.98 - H 3.88 - N 4.91 - S 22.44 The IR (KBr) and NMR (DMSO-d6) spectra agree with the foreseen structure. 6 EXAMPLE 5 To a solution of 7.5 g of (0.03 moles) of 3-bromo-2-oxo-1-pyrrolidinyl acetic acid in 100 ml of anhydrous N,N-dimethylformamide there are subsequently added at + 200C/+250C: 10.5 g (0.105 moles) of triethylamine and 4.15 g (0.045 moles) of thioglycolic acid. The mixture is mantained under stirring for 4 hours at + 200C / + 250C,then the reaction mass is poured in 500 ml of cooled water (+ 50C) and made acidic at pH 2 by addition of 37% hydrogen chloride. The separated crystalline product is isolated by filtration, being then washed on the filter with cold water. The raw product is crystallized from ethanol water= 90:10 and there are obtained: 6.3 g (90%) of 3-carboxymethyl-2-oxo-1 < yrrolidinyl acetic acid; m.p. 54-550C. Analitical data for 08H11NO5 S (MW 233.247) Calculated %: C 41.19 - H 4.75 - N 6,00 - S 13.75 found 96: C 41.12 - H 4.68 - N 5.96 - S 13.77 EXAMPLE 6 A solution of 12.05 g (0.04 moles) of the sodium salt obtained in the example 3 in 60 ml of water is added with 8.7 g (0.082 moles) of sodium carbonate. The temperature is brought to + 1000 and there are added 6.52 (0.05 moles) of the chloride of the 2furancarboxylic acid, then, after 30 minutes of stirring at + 100/+150C the reaction mass is diluted with 120 ml of methylene chloride. It is brought to pH 1.7 with 3N hydrogen chloride, the temperature being maintained at +150/+200C; the organic phase is separated, washed with 20 ml x 2 of water, then dehydrated, over anhydrous sodium sulphate and evaporated under reduced pressure until a volume of 50 ml is obtained. The residual solution is diluted with 120 ml of ethyl ether and then crystallized at + 5 C for 15 hours. It is filtered, washed with ethyl ether (50 ml) and dried under vacuum at 350C. There are thus obtained: 8.8 g (82%) of 3-(2-furoylthio)-2-oxo-1- pyrrolidinyl acetic acid; m.p. 158-160C, Analitical data for C11H11NO5S (MW 269.28) Calculated %: C 49.06 - H 4.12 - N 5.20 - S 11.91 found % : C 48.88 - H 4.09 - N 5.20 - 11.84 EXAMPLE 7 21.2 g (0.2 moles) of sodium carbonate are dissolved in 200 ml of water and the solution is added with 100 g (0.4 moles) of 3-bromo-2-oxo-1 < yrrolidinacetic acid; thereafter there is added over 30 minutes under nitrogen a solution of 33.5 g (0.44 moles) of thioacetic acid, 31.3 g (0.295 moles) of sodium carbonate and 235 ml of water. After 4 hours of stirring at + 200C, 450 ml of ethyl acetate pH is brought to 2 by means of 6 N hydrogen chloride. The aqueous phase is separated and after addition of 150 g of sodium chloride is extracted with further 200 ml of ethyl acetate. The combined phases of ethyl acetate are dehydrated with anhydrous sodium sulphate; after removal of the drying substance by filtration, it is evaporated under reduced pressure until a dense oil of yellow colour is obtained. The raw product is purified by distillation under vacuum. There are thus obtained: 48.6 g (56%) of 3-acetyl-2-oxo-1 -5 pyrrolidinyl acetic acid; b.p. 180-185 C (4.10 bar). Analitical data for 08H11NO4S ( MW 217.25) Calculated %: C 44.23 - H 5.10 - N 6.44 - S 14.75 found %: C 44.85 - H 5.07 - N - 6.47 S 14.68 The IR (film) and NMR (CDC13) spectra are in agreement with the foreseen structure. EXAMPLE 8 A solution of 7.3 g (0.053 moles) of thiobenzoic acid and 8.8 g (0.053 moles) of sodium 2-ethylhexanoate in 30 ml of anhydrous ethyl alcohol is added to 16.5 g (0.66 moles) of ethyl 3-bromo-2-oxo-1yrrolidinyl acetate dissolved in 50 ml of anhydrous ethyl alcohol, the temperature being maintained at + 200C/+250C. After 4 hours of stirring at + 200C/+250C, the solution is evaporated under reduced pressure, then the residue is taken with 20 ml of water and 200 ml of ethyl acetate. The ethyl acetate phase is separated, washed with 50 ml x 2 of an aqueous solution of 2% sodium bicarbonate, then with 50 ml x 2 of water. After drying over anhydrous sodium sulphate the organic phase is evaporated under reduced pressure. The product is purified by distillation under vacuum to give: 11.3 g (69%) of ethyl 3 benzoylthio-2oxo-1-pyrrolidinyl acetate, in form of a yellow oil; b.p. 185 -188 C (9.3.10 bar). Analitical data for C, H NO S (MW 307.372) Calculated 96= C 58.61 - H 5.57 - N 4.56 - S 10.43 found % = C 57. 98 - H 5.53 - N 4.55 - S 10.45 IR (film) and NMR (CDC13) spectra are in agreement with the foressen structure. EXAMPLE 9 A solution of 6.025 g (0.02 moles) of the sodium salt described in the example 3 in 30 ml of water, is added with 4.35 g (0.041 moles) of sodium carbonate. There is subsequently added at + 50/+100C a solution of 3.7 g (0.025 moles) of the chloride of the 1,3,4-thiadiazol-2-yl-carboxylic acid in 15 ml of ethyl acetate; after 1 hour of stirring at the same temperature, the pH of the mixture is brought to 1.8 by 2 N hydrogen chloride. The organic phase is separated, washed with 20 ml x 2 of water, dehydrated over anhydrous sodium sulphate and evaporated at reduced pressure until a solid residue is obtained. The residue is taken with 65 ml of ethyl ether, filtered, washed with ethyl ether (30 ml) and dried under vacuum at 350C. There are thus obtained: 4.8 g (83.6%) of 3-/ (1,3,4-thiadiazol-2-yl)thio/-2-oxo-1- pyrrolidinyl acetic acid; m.p. 172-174 C (dec.) Analitical data for C H N O S (MW 287.32) 9342 Calculated %: C 37.62 - H 3.16 - N 14.62 - S 22.32 found %: C 37.81 - H 3.11 - N 14,44 - S 21.98 EXAMPLE 10 Vials based on sodium 3-(2 -thenoy lthio)-2cxo-1yrrolid iny 1 acetate are prepared, having the following composition: 3-(2 -thenoy lthio)-2oxo-1 pyrro lid iny 1 acetic acid 100 mg sodium carbonate 37 mg apirogenic distilled water q.s. to 3 ml In the same manner vials containing 200 and 300 mg of active principle are prepared. EXAMPLE 11 A syrup is prepared based on one of the compounds of the examples 2 to 9, having the following composition: active ingredient 2 g 70% sorbitol 15 g saccharose 50 g ethyl alcohol 1 ml sodium p-hydroxybenzoate 0.2 mg flavouring essences 0.5 ml saccharin 0.2 g distilled water q.s. to 100 ml A dosing unit contains 200 mg of active principle. In the same manner a syrup containing 3 g of active principle in 100 ml of syrup is prepared, corresponding to the unit dose of 300 mg. EXAMPLE 12 Suppositories are prepared based on one of the compounds of examples 2 to 9, having the following composition: active ingredient 200 mg triglycerides of saturated fatty acids 2800 mg The finely powdered active substance is poured, under stirring, in the melted mass for suppositories, at the temperature of 40 C. The mass is then placed into the moulds which have been previously slightly cooled. Weight of each suppository: 3 g Likewise suppositories of 3 g containing 300 mg of active principle, suppositories of 2 g containing 100 mg of active principle and suppositories of 2 g containing 150 mg of active principle are prepared. EXAMPLE 13 A granulate is prepared for the recoustitution of an oral liquid formulation based on one of the compounds of the examples 2 to 9, having the following composition: active principle 4 g saccharine 0.16 g orange flavour 0.40 g orange lyophilized extract 10 g saccharose q.s. to 100 g The granulate, prepared according to the standard methods, is filled into small envelopes containing 5 g of the same granulate. The content of one small envelope (200 mg of active principle), dissolved into the water, constitutes a suitable unit dose to be administered to adult patients one to three times per day during the treatment, for instance of bronchitis. In the same manner small envelopes are prepared containing 5 g of granulate, wherein 300 mg of active principle are present. EXAMPLE 14 By operating as described in the example 13, small envelopes are prepared containing 5 g of granulate having the following composition: active principle 2 g saccharine 0.16 g orange flavour 0.40 g orange lyophilized extract 10 g saccharose q.s. to 100 g Each small envelope thus prepared contains 100 mg of active principle. Likewise small envelopes containing 150 mg of active principle are prepared. EXAMPLE 15 Capsules based on one of the compounds of the examples 2 to 9 are prepared, having the following composition: active principle 200 mg powdered lactose 100 mg The ingredients are thoroughly admixed so that the active principle is distributed in the lactose mass. The powder is then poured into empty gelatine capsules of the size 1. Likewise capsules containing 300 mf active principle are prepared.

Claims: CLAIMS 1. A compound having the formula EMI15.1 wherein: R is hydrogen , a group of the formula -COR2, where R is a C1 to C8 alkyl group, 2 2 1 8 phenyl or a substituted phenyl group or a heterocyclic group containing from 1 to 3 heteroatoms, such a sulfur, oxygen and nitrogen atoms, or a group of the formula CH2COOR, where R is hydrogen or a C1 to C alkyl group, R is hydrogen, a C1 to 3 1 4 1 1 C8 alkyl group, or a pharmaceutically acceptable salt of the compound of formula I, in which one or both of the substituents R and R1 or R3 and R are hydrogen. 2. A compound according to claim 1, having the formula I wherein R is hydrogen, or pharmaceutically acceptable salt thereof. 3. A compound according to claims 1, having the formula I wherein R is a group COR2, in which R is phenyl, 2-thenoyl, 2-furoyl, 4-thiazolyl, 1,3,4-thiadiazol-2-yl, or 2 a pharmaceutically acceptable salt of the compound I, wherein R1 is hydrogen. 4. 3-(2-thenoylthio)-2-oxo-pyrrolidinyl acetic acid or a pharmaceutically acceptable salt thereof. 5. 3-(2-thenoylthio)-2-oxo-pyrrolidin-1-yl acetic acid sodium salt. 6. A process for the preparation of the compound of the claim 1, characterized by reacting a 3-bromo-pyrrolidin-2one derivative of the formula II EMI15.2 wherein R1 is as defined in the claim 1, with a thiol of the formula III HS-R (III) wherein R is defined as in the claim 1, or with a alkaline salt thereof, eventually in the presence of inorganic or organic bases, in an organic solvent at OOC to 400C, and eventually the resultant product is converted into its pharmaceutically acceptable salt. 7. Modification of the process in accordance with claim 6, characterized by reacting the 3-bromoyrrilidinyl-2one of the formula II, wherein R1 is hydrogen, with a alkaline salt of the thiol of formula III, wherein R is benzoyl, then subjecting to hydrolysis the thus obtained product and the 3-mercapto-2-oxo-pyrrolidinyl acetic acid is isolated. 8. Process in accordance with the modification of the claim 7 characterized by the reaction of the 3-mercapto-2-oxo-pyrrolidinyl acetic acid with a reactive derivative of the 2-thiophencarboxylic acid and by the eventual conversion of the 3-(2thenoylthio)-2-oxo-pyrrolidinyl acetic acid into a pharmaceutically acceptable salt thereof. 9. A pharmaceutical composition containing as the active ingredient a compound as defined in any one of the claims 1 to 5. 10.A pharmaceutical composition according to claim 9, characterized by being formulated in dosing units. 11. A pharmaceutical composition according to claim 10, containing from 100 to 500 mg of the active ingredient for dosing unit in admixture with a pharmaceutical exc ip ients. Milan, 30 March 1984

Inventors: COPPI, GERMANO, DALL'ASTA, LEONE, SCEVOLA, MARIO ERCOLE
Applicants: PROTER S.P.A.
Application year: 1985
Main classification: C07D207
IPC codes: C07D417, C07D207, C07D409, C07D405