6-(SUBSTITUTED METHYLENE)PENEMS

Abstract: Compounds of the general formula (II): in which N⁺ denotes an unsubstituted or substituted nitrogen-containing heterocyclyl ring bonded to the remainder of the molecule through a ring nitrogen atom and carrying a positive charge on said nitrogen atom; and the wavy line denotes either the E- or Z-isomeric position, are novel and are useful in the treatment of antibacterial infection in humans or animals.

Description: This invention relates to novel β-lactam compounds and in particular to novel 6-(substituted methylene) penems which have β-lactamase inhibitory and antibacterial properties. The compounds are therefore useful in the treatment of antibacterial infections in humans or animals, either alone or in combination with other antibiotics. European Patent Publication No. EP 0 154 132 A (Beecham; published 11 September 1985) (the contents of which is incorporated herein by reference thereto) describes compounds of the general formula I, which exhibit β-lactamase inhibitory action and synergistic activity: and their pharmaceutically acceptable salts and in - vivo hydrolysable esters, in which one of R¹ and R² denotes hydrogen, the other of R¹ and R² denotes an unsubstituted or substituted five-membered hetero-aromatic ring bonded through a carbon atom thereof and having one hetero-atom selected from nitrogen, oxygen and sulphur and additionally having from one to three nitrogen atoms, and R³ denotes hydrogen or an organic group. Such compounds are advantageously in the form of the 5R-isomer, that is to say in the form of structure IA: Among the compounds described in EP 0 154 132 A are compounds of the general formula I in which R¹ or R², preferably R¹, denotes a triazolyl group, especially a 1-substituted-1,2,3-triazol-4-yl group, and the other of R¹ and R² denotes hydrogen. More specifically, the said publication describes the compound of the general formula IA in which R¹ denotes a 1-methyl-1,2,3-triazol-4-yl group and each of R² and R³ denotes hydrogen, namely: (5R) (Z)-6-(1-methyl-1,2,3-triazol-4-yl-methylene) penem-3-carboxylic acid; as well as its pharmaceutically acceptable salts and in - vivo hydrolysable esters. Further crystalline and hydrated forms of that compound and its salts are described in European Patent Publication No. EP 0 210 814 A (Beecham; published 04 February 1987) (the contents of which is incorporated herein by reference thereto). Further details of suitable esters and salts of compounds of the general formula I, and also details of methods of preparing the compounds and the manner of formulating them into pharmaceutical compositions and using them for therapeutic treatment, are given in No. EP 0 154 132 A. Improved methods of preparing the compounds of the general formula I are described in European Patent Publication No. EP 0 232 966 A (Beecham; published 19 August 1987) (the contents of which is incorporated herein by reference thereto). It has now been found that certain 6-(1-substituted 1,2,3-triazol-4-yl-methylene)penems exhibit improved activity as compared with the previously described compounds. Accordingly, the present invention provides a compound of the general formula II in which denotes an unsubstituted or substituted nitrogen-containing heterocyclyl group bonded to the remainder of the molecule through a ring nitrogen atom and carrying a positive charge on said nitrogen atom; the wavy line denotes either the E- or Z-isomeric position, wherein substituents for the nitrogen-containing heterocyclyl group include unsubstituted or substituted (C₁₋₆)alkyl, (C₂₋₆)alkenyl, (C₂₋₆)alkynyl, (C₃₋₇)cycloalkyl, (C₃₋₇)cycloalkyl(C₁₋₆)alkyl groups, aryl, aryl(C₁₋₆)alkyl, (C₁₋₆)alkanoyl, (C₁₋₆)alkanoyloxy, heterocyclyl, amino, (C₁₋₆)alkanoylamino, (mono or di)-(C₁₋₆)alkylamino, hydroxy, (C₁₋₆)alkylsulphinyl, (C₁₋₆)alkylsulphonyl, heterocyclylthio, arylthio, sulphamoyl, carbamoyl, amidino, guanidino, nitro, halogen, carboxy esters, arylcarbonyl, heterocyclylcarbonyl groups and divalent substituents forming, with the aromatic nitrogen-containing heterocyclyl ring, a bicyclic ring system, and wherein the term 'heterocyclyl' as used herein in the above list of substituents denotes aromatic and non-aromatic, single and fused, rings containing up to four hetero-atoms in each ring selected from oxygen, nitrogen and sulphur, which rings may be unsubstituted or substituted by up to three groups selected from halogen, (C₁₋₆)alkyl, (C₁₋₆)alkoxy, halo(C₁₋₆)alkyl, hydroxy, amino, carboxy, (C₁₋₆)alkoxycarbonyl, (C₁₋₆)alkoxycarbonyl(C₁₋₆)alkyl, aryl, (C₁₋₆)alkylthio, arylthio, mercapto and oxo groups, and wherein the term 'aryl' as used herein includes phenyl and naphthyl, which may be unsubstituted or substituted by up to five groups selected from halogen, (C₁₋₆)alkyl, phenyl, (C₁₋₆)alkoxy, halo(C₁₋₆)alkyl, hydroxy, amino, nitro, carboxy, (C₁₋₆)alkoxycarbonyl, (C₁₋₆)alkoxycarbonyl (C₁₋₆)alkyl, (C₁₋₆)alkylcarbonyloxy, (C₁₋₆)alkylcarbonyl (C₁₋₆)alkylthio, arylthio, and mercapto groups. The nitrogen-containing heterocylyl group may be monocyclic or bicyclic. In the case of a bicyclic group, the second ring may be a heterocyclic ring or a carbocyclic ring. The nitrogen-containing heterocyclyl group may suitably contain up to 6, more usually 5 or 6, ring atoms in the or each ring, with up to four hetero-atoms in the or each ring selected from oxygen, nitrogen and sulphur, there being at least one ring nitrogen atom. The nitrogen-containing heterocyclyl group is advantageously an unsubstituted or substituted pyrid-1-yl group. Examples of divalent substituents forming with the heterocyclyl ring a bicyclic ring system are (C₁₋₆) alkylene and (C₂₋₆) alkenylene. Aryl groups are preferably substituted by up to three of the substituents listed above as substituents for aryl groups. The compounds of the general formula II constitute internal salts with a positive charge on the nitrogen atom of the heterocyclyl ring and a negative charge on the 3-carboxy group of the penem ring system. The compounds of the general formula II may exist in two optically active forms and it is to be understood that both such forms as well as racemic mixtures thereof are embraced by the present invention. It is believed that the more active form is that of structure IIA: in which is defined as above. Moreover, the compounds of the general formula II may exist in two isomeric forms at the methylene group, that is to say at the 8-position, namely the E- and Z-isomeric forms. The Z-isomer is preferred as generally being the more active form. Examples of individual compounds according to the invention include: (5R)-(Z)-6-[1-(2-pyridinioethyl)-1,2,3-triazol-4-yl-methylene]penem-3-carboxylate; (5R)-(Z)-6-(1-[2-(3-ethylpyridinio)ethyl]-1,2,3-triazol-4-ylmethylene)penem-3-carboxylate; (5R)-(Z)-6-(1-[2-(4-methylpyridinio)ethyl]-1,2,3-triazol-4-ylmethylene)penem-3-carboxylate; (5R)-(Z)-6-(1-[2-(2-methylpyridinio)ethyl]-1,2,3-triazol-4-ylmethylene)penem-3-carboxylate; (5R)-(Z)-6-(1-[2-(4-cyclopropylpyridinio)ethyl]-1,2,3-triazol-4-ylmethylene)penem-3-carboxylate; (5R)-(Z)-6-(1-[2-(2,3-cyclopentenopyridinio)ethyl]-1,2,3-triazol-4-ylmethylene)penem-3-carboxylate; (5R)-(Z)-6-(1-[2-(4-phenylpyridinio)ethyl]-1,2,3-triazol-4-ylmethylene)penem-3-carboxylate; (5R)-(Z)-6-(1-[2-(3-hydroxymethylpyridinio)ethyl]-1,2,3-triazol-4-ylmethylene)penem-3-carboxylate; and (5R)-(Z)-6-[1-(2-pyridinioethyl)-1,2,3-triazol-4-ylmethylene]penem-3-carboxylate hemihydrate. The compounds according to the invention are advantageously provided in crystalline form, which will in some cases also be in hydrated form. A compound of the general formula II given above, may be prepared by the reaction of a compound of the formula in which R x denotes a carboxy-protecting group, is reacted with trifluoromethanesulphonic anhydride and a base, and simultaneously or subsequently with a compound of the general formula wherein denotes an unsubstituted or substituted aromatic nitrogen-containing heterocyclyl compound, followed by removal of the carboxy-protecting group R x . In many cases, the heterocyclyl compound of the formula IV will be sufficiently basic to serve as the base (e.g. pyridine), whereas in other cases it may be advantageous to include a separate base in the reaction (e.g. 2,6-lutidine). Suitable carboxy-protecting groups R x are those given in EP 0 232 966A. It has been found that p-methoxybenzyl is particularly suitable for use as the carboxy-protecting group, in which case its removal may suitably be effected by treatment with aluminium trichloride and anisole. The reaction with the trifluoromethanesulphonic anhydride and, when used, the treatment with the aluminium trichloride/anisole are both suitable carried out at a low temperature, advantageously from -60 o C to -20 o C, suitably about -40 o C. The reaction with the nitrogen-containing heterocyclyl compound is suitably carried out at from -10 o C to +30 o C, preferably about 0 o C. Removal of the carboxy-protecting group R x generates the desired internal salt. A compound of the formula III given above may be prepared using the methods described in the above-mentioned EP 0 232 966 A. In particular, such compounds may be prepared using the procedure described as 'Route F' in that publication in which R¹² denotes the moiety in which the hydroxy group may optionally be protected. Thus, a 6-halopenem may be reacted with an aldehyde of the formula in which R o denotes a hydroxy-protecting group. Examples of suitable hydroxy protecting groups R o include trityl (triphenylmethyl), dimethoxytrityl (4,4'-dimethoxy-triphenylmethyl), trimethoxytrityl (4,4',4''-trimethoxy-triphenyl-methyl), trimethylsilyl, t-butyldimethylsilyl, t-butyldiphenylsilyl, benzyloxycarbonyl, p -methoxybenzyloxycarbonyl, 2-(trimethylsilyl)ethoxycarbonyl, acetonyloxycarbonyl, and allyloxycarbonyl groups. An aldehyde of the general formula VI may, for example, conveniently be prepared from an alkyl 1-(2-hydroxyethyl)-1,2,3-triazole-4-carboxylate (prepared according to the method of S.M. Spojanovic, Collect, Czeck. Chem. Comm. , 1967, 32 , 2155), first by introduction of the hydroxy-protecting group in a conventional manner, for example by reaction with di- or tri-methoxytrityl chloride, followed by reduction of the carboxylate group to a primary alcohol group, and then oxidation to the desired aldehyde function. Following reaction of the aldehyde of the formula VI with the 6-halopenem, and subsequent reductive elimination of the halohydrin thus formed, to give a 6-methylene-penem, as described in EP 0 232 966 A, the hydroxy protecting group may be removed in a conventional manner, for example by acidic hydrolysis, to give the desired compound of the formula IV. As indicated previously, the compounds according to the invention have β-lactamase inhibitory activity and are useful in the treatment of bacterial infections. Accordingly, the present invention also provides a method of treating bacterial infection which comprises administering to a human or animal in need thereof an antibacterially effective amount or a β-lactamase inhibitory amount of compound of general formula II. Advantageously, said compound is administered to said human or animal in conjunction with the prior, simultaneous or subsequent administration of a penicillin, cephalosporin, or other β-lactam antibiotic. Details of administering the compound according to the invention are given in EP 0 154 132A. Accordingly, according to a further aspect, the present invention provides a pharmaceutical composition comprising a compound according to the invention in admixture or conjunction with a pharmaceutically acceptable carrier. The composition may also comprise a penicillin, cephalosporin or other β-lactam antibiotic . Details of formulating such compositions and using the compound according to the invention are given in EP 0 154 132 A. The following Preparations 1-6 and the following Scheme 1 illustrate the preparation of a compound of the formula IV, and Examples 1-9 and Scheme 2 illustrate the preparation therefrom of compounds according to the present invention. In the preparations and examples, all temperatures quoted are in o C. In the formulae in Schemes 1 and 2: DMT denotes 4,4'-dimethoxytrityl, and pMB denotes p -methoxybenzyl. Preparation 1 Ethyl 1-(2-Hydroxyethyl)-1,2,3-triazole-4-carboxylate A solution of ethanolamine (60ml, 1mole) in methanol (320ml) at 5 o was treated with formic acid until a pH of 5 was obtained. A solution of ethyl α-formyldiazoacetate (crude, approximately 0.3mole) in methanol (320ml) was then added and the mixture stirred at room temperature for two days. The mixture was then evaporated, chloroform (1 litre), then water (200ml) was added and the mixture was treated with sodium bicarbonate until a pH of 7 was reached. The phases were separated and the aqueous phase saturated with sodium chloride and extracted with chloroform (6 x 300ml). The combined organic phases were dried (MgSO₄), filtered and evaporated. The residue was then dissolved in toluene (approximately 100ml). The resulting crystalline solid was filtered, washed with ether and dried to provide the title compound (41.6g) as a solid; ν max (nujol) 3320, 3140, 1725cm-¹; δ (CDCl₃), 1.38 (3H, t, J 7.5Hz), 4.00-4.80 (7H, m, becomes 6H, m on D₂O exch), 8.40 (1H, s). This material was pure enough for further synthetic progression. Preparation 2 Ethyl 1-[2-(4,4'-Dimethoxytrityloxy)ethyl]-1,2,3-triazole-4-carboxylate A solution of the product from Preparation 1 (20.3g) in dry dichloromethane (200ml) at 5 o was sequentially treated with triethylamine (15.4ml) and 4,4'-dimethoxytrityl chloride (37.4g). The reaction mixture was warmed to room temperature and, after 1 hour, ethyl acetate (800ml) was added. The mixture was washed with 0.2N HCl, brine, then dried (MgSO₄) and evaporated. The residue was chromatographed on silica eluting with ethyl acetate/hexane mixtures to provide the title compound as an amorphous solid (41.2g); ν max (CHCl₃) 1725cm-¹; δ (CDCl₃), 1.40 (3H, t, J 6.5Hz), 3.44-3.80 (m) overlaying 3.68 (s) (together 8H), 4.35-4.69 (4H, m), 6.82 (4H, d, J 9.0Hz), 7.25 (4H, d, J 9.0Hz), 7.30 (5H, s), 8.22 (1H, s). Preparation 3 1-[2-(4,4'-Dimethoxytrityloxy)ethyl]-4-hydroxymethyl-1,2,3-triazole A solution of the product from Preparation 2 (40g) in tetrahydrofuran (400ml) at 5 o under argon was treated with lithium aluminium hydride (4.67g). After 30 minutes the cooling bath was removed and after a further hour water (175ml) was carefully added. The resulting gel was treated with ethyl acetate (2 litres) and filtered. The filtrate was washed with water and brine, then dried and evaporated. The residue was chromatographed on silica eluting with ethyl acetate/hexane mixtures to give the title compound (34.5g) as an amorphous solid; δ (CDCl₃) 2.93 (1H, bs), 3.30-3.55 (2H, m), 3.77 (6H, s), 4.30-4.60 (2H, m), 4.81 (2H, s), 6.83 (4H, d, J 9.0Hz), 7.23 (4H, d, J 9.0Hz), 7.27 (5H, bs), 7.67 (1H, s). Preparation 4 1-[2-(4,4'-Dimethoxytrityloxy)ethyl]-1,2,3-triazole-4-carboxaldehyde A solution of the product from Preparation 3 (34.5g) in benzene (600ml) was treated with manganese dioxide (48.3g) and the mixture was refluxed with provision for the azeotropic removal of water (Dean and Stark apparatus containing 4A molecular sieves) for 18 hours. The reaction mixture was diluted with dichloromethane (1.5 litres) and filtered through Kieselguhr, washing the pad well with dichloromethane. The filtrate was evaporated and chromatographed on silica eluting with ethyl acetate/hexane mixtures to give the title compound (27g) as an amorphous solid. ν max (CHCl₃) 1705cm-¹; δ (CDCl₃), 3.60 (2H, t, J 4.5Hz), 3.76 (6H, s), 4.50 (2H, t, J 4.5Hz), 6.81 (4H, d, J 8.5Hz), 7.22 (4H, d, J 8.5Hz), 7.29 (5H, s), 8.21 (1H, s), 10.15 (1H, s). Preparation 5 (5R) p-Methoxybenzyl 6-(1-[2-(4,4'-Dimethoxytrityloxy)ethyl]-1,2,3-triazole-4-ylmethylene)penem-3-carboxylate A solution of diphenylamine (6.03g) in dry tetrahydrofuran (THF) (150ml) at -10 o under argon was treated with a solution of n -butyl lithium (1.5M, 21.8ml) in hexane. After 10 minutes the reaction mixture was cooled to -78 o and sequentially treated with a solution of (5R,6S) p -methoxybenzyl 6-bromopenem-3-carboxylate (11.35g) (EP 0 232 966 A) in THF (50ml), then a solution of the product from Preparation 4 (13.5g) in THF (50ml) and finally acetic anhydride (9.61ml). The cooling bath was removed and the reaction mixture was allowed to reach room temperature. The reaction mixture was then diluted with ethyl acetate (1 litre), washed with saturated sodium bicarbonate solution, and brine, then dried (MgSO₄) and evaporated. The residue was dissolved in dimethylformamide (200ml) and treated with ammonium chloride (4.6g), N,N,N',N'-tetramethylethylenediamine dihydrochloride (4.09g) and zinc powder (5.32g), and then vigorously stirred for 1 hour. The reaction mixture was then diluted with ethyl acetate (1.5 litres) washed with 0.2N HCl (1 litre), water (1 litre), saturated sodium bicarbonate solution (500ml) and brine (500ml), then dried (MgSO₄) and evaporated. The residue was chromatographed on silica eluting with ethyl acetate/hexane mixtures to give a 1:5 mixture of E and Z isomers of the title compound as a yellow amorphous solid (13.75g); ν max (CHCl₃) 1780, 1710, 1615cm-¹; δ (CDCl₃) inter alia 6.43 (¹/₅H, s, C5-H; E isomer), 6.63 (⁴/₅H, d, J 0.8Hz, C5-H; Z isomer), 7.81 (⁴/₅H, s, C5'-H; Z isomer), 8.92 (¹/₅H, s, C5'-H; E isomer). Preparation 6 p-Methoxybenzyl (5R)-(Z)-6-[1-(2-Hydroxyethyl)-1,2,3-triazol-4-ylmethylene)penem-3-carboxylate A solution of the mixture of products from Preparation 6 (13.75g) in dichloromethane (1 litre) at 5 o C under argon was treated with formic acid (27.5ml). After 1 hour water (300ml) was added, followed by a solution of sodium hydroxide (27.5g) in water (50ml). The pH of the aqueous layer was adjusted to pH 9 by the addition of more sodium hydroxide solution. The organic phase was separated, washed with water (200ml), brine (200ml), then dried (MgSO₄) and evaporated. On standing the residue was observed to crystallise; ethyl acetate (100ml) was added and the mixture warmed. The resulting cyrstalline solid (1.89g) was collected by filtration and dried. This material was identified as the Z -isomer of the title compound; mp 137-140 o (yellow needles from ethyl acetate); [α] D ²⁰ +420 o (c 0.5 in DMSO); λ max (2%) CHCl₃/EtOH), 288nm (ε m 25,100); ν max (nujol) 3500, 1780, 1695cm⁻¹; δ (d₆-DMSO), 3.70-3.85 (m) overlaying 3.76 (s) (together 5H), 4.47 (2H, t, J 5.2Hz), 5.09 (1H, t, J 5.2Hz), 5.16 (2H, s), 6.67 (1H, d, J 0.8Hz), 6.94 (2H, d, J 8.6Hz), 7.35 (s) overlaying 7.37 (d, J 8.3Hz) (together 3H), 7.73 (1H, s), 8.42 (1H, s). (Found C, 55.1; H, 4.3; N, 13.7; S, 7.7. C₁₉H₁₈N₄O₅S requires C, 55.1; H, 4.4; N, 13.5; S, 7.7%). The mother liquors were concentrated and chromatographed on silica eluting with ethyl acetate/hexane mixtures to give a mixture of E - and Z -isomers of the title compound. A further quantity (0.86g) of the Z -isomer was obtained by careful crystallisation of this mixture from ethyl acetate/hexane. Continued elution of the column gave the Z -isomer of the title compound (1.19g). Example 1 (5R)-(Z)-6-[1-(2-Pyridinioethyl)-1,2,3-triazol-4-yl-methylene]penem-3-carboxylate A solution of p -methoxybenzyl (5R)-(Z)-6-[1-(2-hydroxyethyl)-1,2,3-triazol-4-ylmethylene]penem-3-carboxylate (1g) and pyridine (5ml) in dichloromethane (100ml) was cooled to -40 o C and treated with trifluoromethane- sulphonic anhydride (1.6ml). The solution was warmed to 0 o C and stirred for 1 hour at ice-bath temperature, diluted to 1 litre with dichloromethane and washed with 2% aqueous citric acid (1 litre) and water (1 litre). The solution was dried over anhydrous magnesium sulphate and evaporated under reduced pressure to 80ml. A solution of anhydrous aluminium trichloride (1g) in anisole (16ml)/dichloromethane (4ml) was cooled to -40 o C under argon and treated over 5 minutes with the above dichloromethane solution. The mixture was stirred at -40 o C for 15 minutes, treated with 0.5M disodium hydrogen phosphate solution (100ml) and allowed to warm to room temperature while stirring vigorously. The suspension was filtered through celite, washing through with water-until the filtrate became colourless. The layers of the filtrate were separated and the aqueous washed with dichloromethane (50ml) and ether (50ml) and evaporated to 20ml. This solution was added to a column of HP20SS and the polar materials washed through with water. The required penem was eluted off with 5% acetone/water and the solutions containing penem were combined and evaporated to 50ml then freeze-dried. The title compound was thus obtained as a yellow solid (220mg): [α] D ²⁰ +297 o (c. 0.35; H₂O); ν max (KBr) 1758, 1688, 1638, 1601,1579, 1551 and 1358cm-¹; λ max (H₂O) 266 (s) (ε 22180), 277 (ε 23360) and 371nm (ε 1880); δ (D₂O, with HOD at 4.80 δ) 5.1-5.3 (4H, m), 6.52 (1H, s), 7.00 (1H, s), 7.13 (1H, s), 8.03 (2H, t, J 7Hz), 8.22 (1H, s), 8.59 (1H, t, J 7Hz), 8.68 (2H, d, J 7Hz). Example 2 (5R)-(Z)-6-(1-[2-(3-Ethylpyridinio)ethyl]-1,2,3-triazol-4-ylmethylene)penem-3-carboxylate The title compound was prepared analogously to the product of Example 1, and was obtained as a yellow solid (53%): ν max (KBr) 1763, 1689, 1596, 1550 and 1370cm⁻¹; δ (D₂O, with HOD at 4.80 δ) 1.14 (3H, t, J 7.5Hz), 2.75 (2H, q, J 7.5Hz), 5.11 (4H, s), 6.52 (1H, s), 7.00 (1H, s), 7.13 (1H, s), 7.94 (1H, dd, J 8 and 6Hz), 8.19 (1H, s), 8.30 (1H, s), 8.42 (1H, d, J 8Hz), 8.55 (1H, d, J 6Hz). Example 3 (5R)-(Z)-6-(1-[2-(4-Methylpyridinio)ethyl]-1,2,3-triazol-4-ylmethylene)penem-3-carboxylate The title compound was prepared analogously to the product of Example 1, and was obtained as a yellow solid (34%): [α] D ²⁴ +264 o (c. 0.4; H₂O); ν max (KBr) 1763, 1684, 1640, 1597, 1550 and 1375 cm-¹; λ max (H₂O) 264 (s) (ε 16800), 277 (ε 18920), and 371nm (ε 1430); δ (D₂O with HOD at 4.80 δ), 2.62 (3H, s), 5.08 (4H, broad s), 6.50 (1H, s), 6.98 (1H, s), 7.11 (1H, s), 7.81 (2H, d, J 6Hz), 8.20 (1H, s), 8.42 (2H, d, J 6Hz). Example 4 (5R)-(Z)-6-(1-[2-(2-Methylpyridinio)ethyl]-1,2,3-triazol-4-ylmethylene)penem-3-carboxylate The title compound was prepared analogously to the product of Example 1, and was obtained as a yellow solid (32%): [α] D ²³ +322 o (c. 0.5; H₂O); ν max (KBr) 1762, 1684, 1629, 1596, 1550 and 1377cm-¹; λ max (H₂O) 274 (ε 24050) and 371nm (ε 1662); δ (D₂O with HOD at 4.80 δ) 2.72 (3H, s), 5.14 (4H, s), 6.52 (1H, s), 6.99 (1H, s), 7.13 (1H, s), 7.77 (1H, t, J 7Hz), 7.95 (1H, d, J 7Hz), 8.24 (1H, s), 8.35 (1H, d, J 7Hz), 8.42 (1H, t, J 7Hz). Example 5 (5R)-(Z)-6-(1-[2-(4-Cyclopropylpyridinio)ethyl]-1,2,3-triazol-4-ylmethylene)penem-3-carboxylate The title compound was prepared analogously to the product of Example 1, and was obtained as a yellow solid (61%): [α] D ²¹ +309 o (c. 0.1; H₂O); ν max (KBr) 1781, 1685, 1638, 1569, 1544 and 1378cm-¹; λmax (H₂O) 262 (ε 23000), and 370 nm (ε 1245); δ (D₂O with HOD at 4.80 δ) 1.0-1.2 (2H, m), 1.4-1.6 (2H, m), 2.1-2.3 (1H, m), 4.9-5.2 (4H, m), 6.57 (1H, s), 7.06 (1H, s), 7.18 (1H, s), 7.59 (2H d, J 7Hz), 8.18 (1H, s), 8.28 (2H, d, J 7Hz). Example 6 (5R)-(Z)-6-(1-[2-(2,3-Cyclopentenopyridinio)ethyl]-1,2,3-triazol-4-ylmethylene)penem-3-carboxylate The title compound was prepared analogously to the product of Example 1, using 2,3-cyclopentenopyridine in place of pyridine, and was obtained as a yellow solid (60%): [α] D ²⁰ + 310 o (c. 0.7; H₂O); ν max (KBr) 1763, 1684, 1595, 1550 and 1369cm-¹; λ max (H₂O) 278 (ε 27880) and 372 nm (ε 1520); δ (D₂O with HOD at 4.80 δ) 2.14 (2H, quintet, J 7.5Hz), 2.7-3.1 (2H, m), 3.11 (2H, t, J 7.5Hz), 4.9-5.2 (4H, m), 6.47 (1H, s), 6.94 (1H, s), 7.09 (1H, s), 7.70 (1H, t, J 7Hz), 8.21 (1H, s), 8.28 (2H, d, J 7Hz). Example 7 (5R)-(Z)-6-(1-[2-(4-Phenylpyridinio)ethyl]-1,2,3-triazol-4-ylmethylene)penem-3-carboxylate A solution of p -methoxybenzyl (5R)-(Z)-6-[1-(2-hydroxyethyl)-1,2,3-triazol-4-ylmethylene]penem-3-carboxylate (100mg), 2,6-lutidine (0.116ml) and 4-phenylpyridine (775mg) in dichloromethane (10ml) was cooled to -40 o C and treated with trifluoromethanesulphonic anhydride (0.168ml). The solution was warmed to 0 o C and stirred for 1 hour at ice-bath temperature, diluted to 50ml with dichloromethane and washed with 0.5N hydrochloric acid (50ml) and water (50ml). The solution was dried over anhydrous magnesium sulphate and evaporated under reduced pressure to 2ml. A solution of anhydrous aluminium trichloride (120mg) in anisole (3.2ml)/dichloromethane (0.8ml) was cooled to -40 o C under argon and treated over 1 minute with the above dichloromethane solution. The mixture was stirred at -40 o C for 10 minutes, treated with 0.5M disodium hydrogen phosphate (11ml) and allowed to warm to room temperature while stirring vigorously. The suspension was filtered through celite, washing through with water (100ml) and 1:1 glacial acetic acid/water (100ml). The layers of the filtrate were separated and the aqueous washed with dichloromethane (100ml) and ether (100ml) and filtered through a glass fibre pad. The aqueous acetic acid solution was evaporated under reduced pressure to about 2ml and the resulting yellow solid was filtered off, washed with water and acetone and then dried under vacuum over P₂O₅, giving the title compound (96mg): [α] D ¹⁹ +211 o (c. 0.4; H₂O/CH₃COOH 1:1); ν max (KBr) 1775, 1690, 1636, 1599, 1544 and 1364cm-¹; λ max (H₂O/CH₃COOH 1:1) 288nm (ε 20470); δ (D₂O/CD₃COOD 1:1 with acetone at 2.2 δ) 5.25 (4H, broad s), 6.60 (1H, s), 7.24 (1H, s), 7.50 (1H, s), 7.6-7.7 (3H, m), 7.9-8.0 (2H, m), 8.3-8.4 (3H, m), 8.76 (2H, d, J 7Hz). Example 8 (5R)-(Z)-6-(1-[2-(3-Hydroxymethylpyridinio)ethyl]-1,2,3-triazol-4-ylmethylene)penem-3-carboxylate A solution of p -methoxybenzyl (5R)-(Z)-6-[1-(2-hydroxyethyl)-1,2,3-triazol-4-ylmethylene]penem-3-carboxylate (50mg) and 2,6-lutidine (0.06ml) in dichloromethane (6ml) was cooled to -40 o C and treated with trifluoromethanesulphonic anhydride (0.06ml). After 5 minutes 3-pyridylcarbinol (0.12ml) was added and the reaction mixture allowed to warm to 0 o C. A procedure analogous to that of Example 1 was then followed, to provide the title compound as a yellow solid (3.3mg) : ν max (KBr) 1762, 1598, 1551 and 1383cm-¹; δ (D₂O with HOD at 4.80 δ) 5.15 (6H, broad s), 6.54 (1H, s), 7.01 (1H, s), 7.14 (1H, s), 7.98 (1H, dd, J 8 and 6Hz) 8.21 (1H, s), 8.4-8.7 (3H, m). Example 9 (5R)-(Z)-6-[1-(2-Pyridinioethyl)-1,2,3-triazol-4-ylmethylene]penem-3-carboxylate hemihydrate A solution of the product from Example 1 (130mg) was dissolved in water (0.65ml) and the solution left to crystallise at 5 o . After 3 hours the crystalline solid was removed by filtration, washed with acetone (1ml), ether (2ml) then dried to provide the title compound (54mg) as yellow needles; [α] D ²⁰ (c = 1 in H₂O) +397.8 o ; λ max (H₂O) 266nm (ε 24400), 279 (25580), 372 (2120); ν max (KBr) 3423, 1757, 1688, 1637 1601cm-¹; δ (D₂O) 5.08-5.25 (4H, m), 6.51 (1H, s), 6.98 (1H, s), 7.12 (1H, s), 8.02 (2H, dd, J 6.8, 7.9Hz), 8.20 (1H, s), 8.57 (1H, dt, J 1.3, 7.9Hz), 8.65 (2H, dd, J 1.3, 6.8Hz). (Found: C, 52.8; H, 3.7; N, 18.9; S, 8.8. C₁₆H₁₃N₅O₃S. ½ H₂O requires C, 52.8; H, 3.9; N, 19.2; S, 8.8%).

Claims: A compound of the general formula (II): in which denotes an unsubstituted or substituted aromatic nitrogen-containing heterocyclyl group bonded to the remainder of the molecule through a ring nitrogen atom and carrying a positive charge on said nitrogen atom; the wavy line denotes either the E- or Z-isomeric position; wherein substituents for the aromatic nitrogen-containing heterocyclyl group are selected from (C₁₋₆)alkyl, (C₂₋₆)alkenyl, (C₂₋₆)alkynyl, (C₃₋₇)cycloalkyl, (C₃₋₇)cycloalkyl(C₁₋₆)alkyl groups, aryl, aryl(C₁₋₆)alkyl, (C₁₋₆)alkanoyl, (C₁₋₆)alkanoyloxy, heterocyclyl, amino, (C₁₋₆)alkanoylamino, (mono or di)-(C₁₋₆)alkylamino, hydroxy, (C₁₋₆)alkylsulphinyl, (C₁₋₆)alkylsulphonyl, heterocyclylthio, arylthio, sulphamoyl, carbamoyl, amidino, guanidino, nitro, halogen, carboxy esters, arylcarbonyl, heterocyclylcarbonyl groups and divalent substituents forming, with the aromatic nitrogen-containing heterocyclyl ring, a bicyclic ring system, and wherein term 'heterocyclyl' as used herein in the above list of substituents denotes aromatic and non-aromatic, single and fused, rings containing up to four hetero-atoms in each ring selected from oxygen, nitrogen and sulphur, which rings may be unsubstituted or substituted by up to three groups selected from halogen, (C₁₋₆)alkyl, (C₁₋₆)alkoxy, halo(C₁₋₆)alkyl, hydroxy, amino, carboxy, (C₁₋₆)alkoxycarbonyl, (C₁₋₆)alkoxycarbonyl(C₁₋₆)alkyl, aryl, (C₁₋₆)alkylthio, arylthio, mercapto and oxo groups, and wherein term 'aryl' as used herein denotes phenyl and naphthyl, which may be unsubstituted or substituted by up to five groups selected from halogen, (C₁₋₆)alkyl, phenyl, (C₁₋₆)alkoxy, halo(C₁₋₆)alkyl, hydroxy, amino, nitro, carboxy, (C₁₋₆)alkoxycarbonyl, (C₁₋₆)alkoxycarbonyl(C₁₋₆)alkyl, (C₁₋₆)alkylcarbonyloxy, (C₁₋₆)alkylcarbonyl (C₁₋₆)alkylthio, arylthio, and mercapto groups. A compound according to claim 1, which is of the general formula (IIA): A compound according to claim 1 or claim 2, wherein the aromatic nitrogen-containing heterocyclyl group is monocyclic or bicyclic. A compound according to claim 3, wherein the aromatic nitrogen-containing heterocyclyl group contains up to 6 ring atoms in the or each ring, with up to four hetero-atoms in the or each ring selected from oxygen, nitrogen and sulphur, there being at least one ring nitrogen atom. A compound according to claim 4, wherein the aromatic nitrogen containing heterocyclyl group is an unsubstituted or substituted pyrid-1-yl group. A compound according to any one of claims 1 to 5, wherein the substituents for the aromatic nitrogen containing heterocyclyl group are selected from one or more of the following groups: unsubstituted or substituted (C₁₋₆)alkyl, (C₂₋₆)alkenyl, (C₂₋₆)alkynyl, (C₃₋₇)cycloalkyl, and (C₃₋₇)cycloalkyl(C₁₋₆)alkyl groups, as well as aryl, aryl(C₁₋₆)alkyl, (C₁₋₆)alkanoyl, (C₁₋₆)alkanoyloxy, heterocyclyl, amino, (C₁₋₆)alkanoylamino, (mono or di)-(C₁₋₆)alkylamino, hydroxy, (C₁₋₆)alkylsulphinyl, (C₁₋₆)alkylsulphonyl, heterocyclylthio, arylthio, sulphamoyl, carbamoyl, amidino, guanidino, nitro, halogen, carboxy esters, arylcarbonyl, heterocyclylcarbonyl, (C₁₋₆)alkylene and (C₂₋₆)alkenylene. A compound according to claim 1, which is selected from the following compounds: (5R)-(Z)-6-[1-(2-pyridinioethyl)-1,2,3-triazol-4-yl-methylene)penem-3-carboxylate, (5R)-(Z)-6-(1-[2-(3-ethylpyridinio)ethyl]-1,2,3-triazol-4-ylmethylene)penem-3-carboxylate, (5R)-(Z)-6-(1-[2-(4-methylpyridinio)ethyl]-1,2,3-triazol-4-ylmethylene)penem-3-carboxylate, (5R)-(Z)-6-(1-[2-(2-methylpyridinio)ethyl]-1,2,3-triazol-4-ylmethylene)penem-3-carboxylate, (5R)-(Z)-6-(1-[2-(4-cyclopropylpyridinio)ethyl]-1,2,3-triazol-4-ylmethylene)penem-3-carboxylate, (5R)-(Z)-6-(1-[2-(2,3-cyclopentenopyridinio) ethyl]-1,2,3-triazol-4-ylmethylene)penem-3- carboxylate, (5R)-(Z)-6-(1-[2-(4-phenylpyridinio)ethyl]-1,2,3-triazol-4-ylmethylene)penem-3-carboxylate, (5R)-(Z)-6-(1-[2-(3-hydroxymethylpyridinio)ethyl]-1,2,3-triazol-4-ylmethylene)penem-3-carboxylate, and (5R)-(Z)-6-[1-(2-pyridinioethyl)-1,2,3-triazol-4-ylmethylene)penem-3-carboxylate hemihydrate. A process for the preparation of a compound of the general formula (II) as defined in claim 1, wherein a compound of formula (III): in which R x denotes a carboxy-protecting group, is reacted with trifluoromethanesulphonic anhydride and a base and simultaneously or subsequently with a compound of the general formula wherein denotes an unsubstituted or substituted aromatic nitrogen-containing heterocyclyl compound, followed by removal of the carboxy-protecting group R x . A process according to claim 8, wherein the heterocyclyl compound of formula (IV) serves as the base. A process according to claim 8 or claim 9, wherein the reaction with the compound of formula (III) is carried out at a temperature of between -60 o C and -20 o C. A process according to any one of claims 8 to 10, wherein the reaction with the compound of formula (IV) is carried out at a temperature of between -10 o C and +30 o C. A process according to any one of claims 8 to 11, wherein the compound of formula (III) is prepared by reacting a 6-halopenem with an aldehyde of formula (VI): in which R o denotes a hydroxy-protecting group. A process according to claim 12, wherein R o is selected from one of the following groups: triphenylmethyl, 4,4'-dimethoxytriphenylmethyl, 4,4',4''-trimethoxytriphenylmethyl, trimethylsilyl, t-butyldimethylsilyl, t-butyldiphenylsilyl, benzloxycarbonyl, p -methoxybenzyloxycarbonyl, 2-(trimethylsilyl)ethoxycarbonyl, acetonyloxycarbonyl, and allyloxycarbonyl. A pharmaceutical composition comprising a compound according to any one of claims 1 to 7, in admixture or conjunction with a pharmaceutically acceptable carrier. A pharmaceutical composition according to claim 14, which additionally comprises a penicillin, cephalosporin or other β-lactam antibiotic. A compound according to any one of claims 1 to 7, for use as an active therapeutic substance. A compound according to any one of claims 1 to 7, for use in the treatment of bacterial infections. The use of a compound of general formula (II) as defined in claim 1, for the preparation of a medicament for the treatment of bacterial infections.

Inventors: BROOKS, GERALD, BROOM, NIGEL JOHN PERRYMAN, CLARKE, BRIAN PETER BEECHAM PHARMACEUTICALS
Applicants: BEECHAM GROUP PLC
Application year: 1988
Main classification: C07D499
IPC codes: C07D249, A61P31, C07D499, A61K31