Novel cephalosporin compounds and antibacterial agents

Abstract: Novel cephalosporin compounds of the formula (I): wherein R¹ and R² may be the same or different and are a hydrogen atom or a lower alkyl group of 1 - 5 carbon atoms and A is a hydrogen atom or a nucleophilic compound residue or pharmacologically acceptable salts thereof have excellent antibacterial activity against Gram positive and Gram negative microorganisms.

Description: 1. Field of the Invention This invention relates to novel cephalosporin compounds having antibacterial activity in a wide range including pseudomonas aeruginosa, and more specifically, it relates to novel cephalosporin derivatives having a (Z)-2-(2-aminothiazol-4-yl)-2-(1,5-dihydroxy-4-pyridon-2-yl) alkoxyiminoacetamido group on the 7-position which have an excellent therapeutic effect against diseases in humans and animals due to pathogens and are useful as medicines and veterinary medicines. 2. Description of the Prior Art Cephalosporin antibiotics are widely employed in the treatment of diseases due to pathogenic bacteria, but are hardly satisfactory in view of antibacterial power, antibacterial spectrum, clinical pharmaceutical effect etc. EP-A 0 251 299 describes a cephalosporin compound having the formula: wherin R¹ is a hydrogen atom, a halogen atom, a methoxy group, a vinyl group, or -CH₂-A wherein A is a hydrogen atom, an azido group, an acyloxy group, a carbamoyloxy group, a heterocyclic group, or a heterocyclic thio group. The present inventors had previously discovered that novel cephalosporin derivatives having a 2-(2-aminothiazol-4-yl)-2-(1,5-dihydroxy-4-pyridone-2-carboxamido)acetamido group on the 7-position have strong activity against a wide range of pathogens in Japanese Patent Application Nos. 60-140989, 61-77893 and 61-77894. These derivatives especially have excellent antibacterial power against Pseudomonas aeruginosa and it is believed that the activity is derived from the 1,5-dihydroxy-4-pyridone-2-carboxamido substituent on the 7-position, and further on this occasion, the study on the 1,5-dihydroxy-4-pyridone structure has been developed and the side-chains on the 7-position have been intensively studied, finally to discover that the novel cephalosporin compounds of the formula (I) have a wide range of antibacterial activity against Gram negative bacteria including Pseudomonas aeruginosa and also have particularly strong activity against various β-lactamase producing bacteria, thereby this invention has been accomplished. SUMMARY OF THE INVENTION Accordingly, this invention relates to novel cephalosporin compounds of the general formula (I): wherein R¹ is a hydrogen atom, a methyl group, an ethyl group or a phenyl group, provided that, when R¹ is a hydrogen atom, A is a hydroxy group, a phenylthio group, a halogen- or a hydroxy-substituted phenylthio group; and, when R¹ is a methyl group, an ethyl group or a phenyl group, A is a tetrazolylthio group, a (C₁₋₃)alkyl- or a di (C₁₋₃) alkylamino(C₁₋₃)alkyl-substituted tetrazolylthio group, a thiadiazolylthio group, or a (C₁₋₃)alkyl-substituted thiadiazolylthio group, or pharmacologically acceptable salt thereof. DETAILED DESCRIPTION OF THE INVENTION The compounds of the general formula (I) are synisomers, and where there is an asymmetric carbon in the substituent on the 7-position, D-form and L-form may be present, and this invention excompasses both of D- and L- forms and also DL-form. Further, the 1,5-dihydroxy-4-pyridon-2-yl) alkoxyimino moiety as the substituent on the 7-position may exist as tautomers as described below, and although this invention encompasses both of these, the pyridone form is used for therterminology and the description of the structure. Examples of the pharmacologically acceptable salts of the compounds of the formula (I) of this invention include medicinally acceptable salts, in particular, conventionally employed non-toxic salts, for example, alkali metal salts such as sodium salts and potassium salts, alkaline earth metal salts such as calcium salts and magnesium salts, ammonium salts, organic salts such as those with organic bases, for example, organic amine salts such as triethylamine salts, pyridine salts, ethanolamine salts, triethanolamine salts, dicyclohexylamine salts, basic amino acid salts such as those with lysine or arginine. Examples of the nucleophilic compound residue represented by A in the compounds of the general formula (I) include a hydroxyl group, or a heteroring attached via S, that is, a heterocyclic thio group, or a phenyl, a substituted phenyl group via S group. The heteroring as herein used means a 5-membered ring containing 1 - 4 heteroatoms selected from S and N such as, thiadiazolyl, tetrazolyl, etc., and these heterorings may contain substituents, for example, a lower alkyl group of 1 - 3 carbon atoms, a di-lower-alkylamino-lower-alkyl group of 1 - 3 carbon atoms. Specific examples of the substituent on the 3-position of the compounds of the formula (I) of this invention include the following. phenylthiomethyl, (4-hydroxyphenyl)thiomethyl, (4-fluorophenyl)thiomethyl, (1H-tetrazol-5-yl)thiomethyl, (1-methyl-1H-tetrazol-5-yl)thiomethyl, (1-amino-1H-tetrazol-5-yl)thiomethyl, [1-(2-dimethylaminoethyl)-1H-tetrazol-5-yl]thiomethyl, [1-(2-hydroxyethyl)-1H-tetrazol-5-yl]thiomethyl, [1-(2-carboxyethyl)-1H-tetrazol-5-yl]thiomethyl, (1-carboxymethyl-1H-tetrazol-5-yl)thiomethyl, (1-carbamoylmethyl-1H-tetrazol-5-yl)thiomethyl, (1-sulfomethyl-1H-tetrazol-5-yl)thiomethyl, [1-(2-sulfoethyl)-1H-tetrazol-5-yl]thiomethyl, (1-sulfamoylmethyl-1H-tetrazol-5- yl)thiomethyl, (1,3,4-thiadiazol-5-yl)thiomethyl, (2-methyl-1,3,4-thiadiazol-5-yl)thiomethyl, (2-ethylthio-1,3,4-thiadiazol-5-yl)thiomethyl, (2-carbamoyl-1,3,4-thiadiazol-5-yl)thiomethyl, (2-ethoixycarbonyl-1,3,4-thiadiazol-5-yl)thiomethyl, (2-ethoxy-1,3,4-thiadiazol-5-yl)thiomethyl, (2-trifluoromethyl-1,3,4-thiadiazol-5-yl)thiomethyl, (2-carboxy-1,3,4-thiadiazol-5-yl)thiomethyl, (2-methylamino-1,3,4-thiadiazol-5-yl)thiomethyl, (2-amino-1,3,4-thiadiazol-5-yl)thiomethyl, (2-mercapto-1,3,4-thiadiazol-5-yl)thiomethyl, (2-carbamoylmethyl-1,3,4-thiadiazol-5-yl)thiomethyl, (1,2,3-thiadiazol-5-yl)thiomethyl, (4-methyl-1,2,3-thiadiazol-5-yl)thiomethyl, (4-carbamoyl-1,2,3-thiadiazol-5-yl)thiomethyl, 4-ethoxycarbonyl-1,2,3-thiadiazol-5-yl)thiomethyl, (1,2,4-thiadiazol-5-yl)thiomethyl, (3-methyl-1,2,4-thiadiazol-5-yl)thiomethyl, (3-phenyl-1,2,4-thiadiazol-5-yl)thiomethyl, Synthesis of a protected form of 2-hydroxymethyl-1,5-dihydroxy-4-pyridone which is one of the constituting components for the substituent on the 7-position was conducted according to the process disclosed in Japanese Patent Application No. 60-140989 by the present inventors. That is, it may be obtained by reacting a protected form of kojic acid (II) with hydroxylamine hydrochloride or R⁹ONH₂ or a salt thereof in the presence of pyridine, wherein R⁸ and R⁹ are a removable protecting group such as benzyl, p-nitrobenzyl, o-nitrobenzyl, p-methoxybenzyl, benzhydryl, etc. Further, in the reaction of the compound of the formula (III) and R⁹X (wherein X is a halogen atom or a diazo group), the product may be obtained as (IVa) or (IVb) or a mixture thereof depending on the kind of R⁹X, the reaction solvent and the reaction conditions such as the temperature. The cephalosporin compounds of the general formula (I) of this invention may be produced by the following process A) or B). A) A compound of the general formula (Va) or (Vb): wherein R¹⁰ is a hydrogen atom or a protecting group for the amino group and R¹, R⁸ and R⁹ are as defined above, or a reactive derivative of said carboxylic acid is reacted with a compound of the general formula (VI): wherein R¹¹ is a hydrogen atom or a protecting group for the carboxyl group add A is as defined above, or a salt or silylated product thereof, and thereafter, the protecting group is removed. B) A compound of the general formula (VIIa) or (VIIb): wherein Y is an acetoxy group or a halogen atom, R⁸' is a hydrogen atom or R⁸, R⁹' is a hydrogen atom or R⁹ and R¹, R⁸, R⁹, R¹⁰ and R¹¹ are as defined above is reacted with a nucleophilic compound, and thereafter, if needed, the protecting group is removed, thereby the compound of the general formula (I) is produced. The nucleophilic compound as herein used is a compound corresponding to A in the general formula (I). As the protecting groups for the amino group and the carboxyl group in the above-described general formula, those employed for this purpose in the field of β-lactam and peptide sysnthesis are appropriably employed. Examples of the protecting group for the amino group include phthaloyl, formyl, monochloroacetyl, dichloroacetyl, trichloroacetyl, methoxycarbonyl, ethoxycarbonyl, t-butoxycarbonyl, trichloroethoxycarbonyl, benzyloxycarbonyl, p-nitrobenzyloxycarbonyl, diphenylmethyloxycarbonyl, methoxymethyloxycarbonyl, trityl, trimethylsilyl etc., and examples of the protecting group for the carboxyl group include t-butyl, t-amyl, allyl, benzyl, p-nitrobenzyl, p-methoxybenzyl, benzhydryl, phenyl, p-nitrophenyl, methoxymethyl, ethoxymethyl, benzyloxymethyl, acetoxymethyl, methylthiomethyl, trityl, trichloroethyl, trimethylsilyl and dimethylsilyl. The condensation reaction of the general formulae (Va) or (Vb) and (VI) in Process A may be conducted by using a usual method for acylation used for penicillins and cephalosporins. Examples of the reactive derivative include acid halides, acid anhydrides, active amides and active esters. Preferred examples thereof include acid chlorides, acid bromides, mixed acid anhydrides of e.g. acetic acid, pivalic acid, isovaleric acid and trichloroacetic acid, active amides with pyrazole, imidazole, dimethylpyrazol and benzotriazole, and active esters with p-nitrophenyl ester, 2,4-dinitrophenyl ester, trichlorophenyl ester, 1-hydroxy-1H-pyridone, N-hydroxysuccinimide, N-hydroxybenzotriazole and N-hydroxyphthalimide. Further, in this reaction, where the compound of the general formula (Va) or (Vb) is used in the form of a free acid, it is preferred to carry out the reaction in the presence of a condensing agent; that is, the reaction may be carried out in the presence of a condensing agent such as reagents produced by the reaction of a carbodiimide compound, e.g. N,N-dicyclohexylcarbo-diimide and N-cyclohexyl-N'-morpholinoethylcarbodiimide, N-cyclohexyl-N'-(4-diethylaminocyclohexyl)carbodiimide or an amide compound, e.g., N-methylformamide, N,N-dimethylforamide etc. with a halide such as thionyl chloride, phosphorus oxychloride and phosgene (the so-called Vilsmeier reagents). Of the reactive derivatives in this reaction, the reaction involving the acid halide or the acid anhydride requires the presence of an acid binder, and examples of the acid binder include organic bases such as triethylamine, trimethylamine, ethylisopropylamine, N,N-dimethylamine, N-methylmorpholine, pyridine etc., hydroxides of e.g. sodium, potassium, calcium etc., alkali metal salts such as alkali metal carbonates, bicarbonates and oxiranes such as ethylene oxide and propylene oxide. This reaction is generally carried out in a solvent which does not exert any adverse influences on the reaction, and examples of the solvent which may be used include water, acetone, acetonitrile, dioxane, tetrahydrofuran, ethyl acetate, methylene chloride, chloroform, dichloroethane, N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide or mixed solvents thereof. Although the reaction temperature is not particularly restricted, the reaction is generally conducted at -30°C to 40°C, and for the reacting time, the reaction reaches completion in 30 minutes to 10 hours. The method for removing the protecting group of the thus obtained acylated product may be chosen among a method using an acid and a method using a base, a method using hydrazine depending on the kind of protecting group, and these methods may be conducted by appropriately selecting the conventional methods used in the field of β-lactam and peptide synthesis. The compound of the general formula (Va) or (Vb) may be obtained by reacting a compound of the general formula (VIII): wherein R¹⁰ and R¹¹ are as defined above or a salt thereof with a compound of the general formula (IXa) or (IXb): wherein Z is a halogen atom or a sulfonate group such as mesyloxy, tosyloxy, trifluoromesyloxy etc. and thereafter, if necessary, removing the protecting group for the carboxylic acid. This condensation reaction may be conducted at a temperature in the range of -50°C to 70°C in a solvent and, if necessary, in the presence of a base. The base and the solvent used in this reaction may be chosen among bases and solvents used for the acylation reaction in Process A. The reaction of the general formula (VIIa) or (VIIb) and the nucleophilic compound in Process B may be chosen from methods conventionally employed in the cephalosporin chemistry. That is, the reaction where Y is an acetoxy group in the general formula (VIIa) or (VIIb) is generally preferably conducted in a polar solvent such as water, phosphate buffers, acetone, acetonitrile, N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran, dimethylsulfoxide, dioxane, methanol, ethanol or mixed solvents thereof with water. It is preferred to carry out the reaction in the vicinity of neutrality, and while the reaction temperature is not particularly restricted, it is suitable to conduct at room temperature to about 80°C. The time required for this reaction depends on the reaction conditions, but in general it is 1 - 10 hours. Further, this reaction may be promoted by conducting it in the presence of an alkali metal halide such as sodium iodide, potassium iodide etc. Further, where the intended product is to be produced from the compound of the general formula (VIIa) or (VIIb) wherein Y is a halogen atom, it is preferred to conduct the reaction in a solvent such as acetone, dioxane, tetrahydrofuran, ethyl acetate, acetonitrile, N,N-dimethylformamide, N,N-dimethylacetamide and dimethylsulfoxide under anhydrous conditions. The reaction is generally preferably conducted at 0 - 50°C and it reaches completion in 1 - 5 hours. The compound of the general formula (I) obtained as above may be separated from the reaction mixture in a conventional manner. For example, it is effected by appropriately combining such methods as purification using an absorbing resin, e.g., Amberlite XAD-2 (produced by Rohm & Haas), Diaion HP-20 (produced by Mitsubishi Chemical Industries), precipitation and crystallization. Antibacterial agents containing the compounds of the general formula (I) or salts thereof as the main ingredient may be mainly used in various pharmaceutical forms, for example, injections such as intravenous and intramuscular injections, oral forms such as capsules, tablets and powders, as well as intrarectal dosage forms, oily suppositories and water-soluble suppositories. These various forms may be prepared in a conventional manner by using conventional excipients, fillers, binders, wetting agents, disintegrants, surfactants, lubricants, dispersants, buffers, preservatives, solubilizing aids, antiseptics, flavoring agents and analgesics. Specific embodiments for the production process will be described in more detail in the examples described below. The dosage is appropriately and individually determined in consideration of the severeness of the disease, the age and the sex, but for example, the daily dose for an adult is usually 250 - 3000 mg, and it is administered in portions 1 - 4 times a day. EXAMPLES This invention is described in more detail by the following examples. In the examples, the NMR data are obtained by using 400 MHz NMR and indicated as the δ values against the peak value for water taken as 4.82 in the case of deuterium oxide or as the δvalues against the TMS standard in the case of other deuterated solvents. Reference Example 1 5-p-Methoxybenzyloxy-1-hydroxy-2-hydroxymethyl-4-pyridone (a) 42.6 g of kojic acid is dissolved in 350 ml of N-dimethylformamide, then 82.8 g of anhydrous potassium carbonate and 55 g of p-methoxybenzyl chloride are added thereto, and reacted at 70 - 75°C for 1.5 hours. After the reaction, the reaction mixture is concentrated to about half the volume, and added dropwise to 700 ml of water with ice cooling. The formed precipitates are filtered off, washed with water and ethyl acetate and dried to obtain 59.9 g of 5-p-methoxybenzyloxy-2-hydroxymethyl-4-pyrone. NMR(CDCl₃)δ; 3,80(3H,s), 4.43(2H,s), 4.96(2H,s), 6.50(1H,s), 6.88(2H,d), 7.30(2H,d), 7.51(1H,s) (b) 39.3 g of 5-p-methoxybenzyloxy-2-hydroxymethyl-4-pyrone is dissolved in 600 ml of pyridine, then 52.2 g of hydroxylamine hydrochloride is added thereto, and reacted at 70 - 75°C for 2.5 hours. After the reaction, the reaction mixture is concentrated to about 100 ml and, after adding 100 ml of water thereto, added to a mixed solution of 75 ml of hydrochloric acid and 225 ml of water with ice cooling. The pH is adjusted to 2 - 2.5, and stirring is conducted at the same temperature for 30 minutes. The formed crystals are filtered off, washed with water and then dried to obtain 16.6 f of the title compound. NMR(DMSO-d₆)δ; 3.76(3H,s), 4.46(2H,s), 5.03(2H,s), 6.86(1H,s), 6.93(2H,d), 7.37(2H,d), 7.97(1H,s) Reference Example 2 4-Diphenylmethyloxy-5-p-methoxybenzyloxy-2-hydroxymethyl pyridine-N-oxide 44.3 g of 5-p-methoxybenzyloxy-1-hydroxy-2-hydroxymethyl-4-pyridone is suspended in 320 ml of methyl cellosolve (2-methoxyethanol) and 33.4 ml of triethylamine is added thereto to dissolve. Then, 150 ml of a methyl cellosolve solution containing 46.6 g of diphenyldiazomethane is added,thereto and reacted at 60°C for 5 hours. After the reaction, the reaction mixture is concentrated to about 100 ml, and 200 ml of a mixed solution of ethyl acetate and isopropyl ether (1:1) is added thereto. The formed crude crystals are filtered off, then washed with a mixed solution of ethyl acetate and isopropyl ether (1:1) and isopropyl ether, and dried. This is suspended in 500 ml of dichloromethane, and the insolubles are removed by filtration. The dichloromethane solution is concentrated to a small volume, then ethyl acetate is added thereto, and the formed crystals are filtered off and dried to obtain 42 g of the intended title compound. NMR(CDCl₃)δ; 3.82(3H,s), 4.57(2H,s), 5.06(2H,s), 6.28(1H,s), 6.69(1H,s), 6.89(2H,d), 7.2-7.5(12H,m), 7.91(1H,s) Reference Example 3 1,5-Di-p-methoxybenzyloxy-2-hydroxymethyl-4-pyridone 27.7 g of 5-p-methoxybenzyloxy-1-hydroxy-2-hydroxymethyl-4-pyridone is suspended in 300 ml of N,N-dimethylformamide, then 27.7 g of anhydrous potassium carbonate and 17.3 g of p-methoxybenzyl chloride are added, and reacted at room temperature for 4 hours. The reaction mixture is concentrated to a small volume, then, after adding 600 ml of chloroform, washed with water and then dried on anhydrous magnesium sulfate and further concentrated to about 200 ml. 200 ml of isopropyl ether is added thereto, and the formed crystals are filtered off and dried to obtain 38.9 g of the intended title compound. NMR(CDCl₃)δ; 3.75(3H,2), 3.80(3H,s), 4.49(2H,s), 4.90(2H,s), 5.01(2H,s), 6.47(1H,s), 6.82(2H,d), 6.87(2H,d), 6.98(1H,s), 7.20(2H,d), 7.23(2H,d) Reference Example 4 1-Diphenylmethyloxy-5-p-methoxybenzyloxy-2-hydroxymethyl-4-pyridone 5.54 g of 5-p-methoxybenzyloxy-1-hydroxy-2-hydroxymethyl-4-pyridone is suspended in 40 ml of N,N-dimethylformamide, and then 2.24 g of potassium t-butoxide is added with ice cooling to dissolve. 4.94 g of benzhydryl bromide is added thereto and reacted at room temperature for 2.5 hours. After the reaction, the reaction mixture is concentrated to about 20 ml, which is then added dropwise to a mixed solution of ethyl acetate (200 ml) and water (100 ml). The formed precipitates are filtered off, washed with water and ethyl acetate, and then dried to obtain 7.29 g of the intended title compound. NMR(CDCl₃)δ; 3.78(3H,s), 4.51(2H,s), 4.59(2H,s), 6.18(1H,s), 6.58(1H,s), 6.63(1H,s), 6.82(2H,d), 7.16(2H,d), 7.3-7.5(10H,m) Example A (The compound mentioned below is not comprised by the present invention) (6R,7R)-7-[(Z)-2-(2-Aminothiazole-4-yl)-2-(1,5-dihydroxy-4-pyridone-2-yl)methoxyiminoacetamido]-3-(1-methylpyridinium-4-yl)thiomethyl-ceph-3-em-4-carboxylate (a) 2.2 g of 4-diphenylmethyloxy-5-p-methoxybenzyloxy-2-hydroxymethylpyridine-N-oxide is suspended in 50 ml of dichloromethane, 1 ml of thionyl chloride and one drop of N,N-dimethylformamide are added thereto with ice cooling, and reacted at the same temperature for 3 hours. 40 ml of a saturated sodium bicarbonate aqueous solution and 50 ml of dichloromethane are added thereto. The dichloromethane layer is washed with water, then dried on anhydrous magnesium sulfate, and concentrated to dryness under reduced pressure. The residue is dissolved in 40 ml of N,N-dimethylformamide, then 2.1 g of allyl(Z)-2-(2-trityl-aminothiazole-4-yl)2-hydroxyiminoacetate and 1.24 g of potassium carbonate anhydride are added thereto, and reacted overnight at room temperature. 200 ml of chloroform is added to the reaction mixture. It is washed with water, dilute hydrochloric acid and water successively, dried anhydrous on magnesium sulfate, and then concentrated to dryness under reduced pressure. The residue is purified by silica gel column chromatography to obtain 2.18 g of allyl(Z)-2-(2-tritylaminothiazole-4-yl)-2-(4-diphenylmethyloxy-5-p-methoxybenzyloxypyridine-N-oxid-2-yl)methoxyiminoacetate. NMR(CDCl₃)δ; 3.83(3H,s), 4.89(2H,d), 5.04(2H,s), 5.37(2H,dd), 5.38(2H,s), 6.0(1H,m), 6.40(1H,s), 6.57(1H,s), 6.90(2H,d), 6.93(1H,s), 6.96(1H,s), 7.1-7.5(27H,m), 7.87(1H,s) (b) 1.74 g of the allyl ester compound obtained in (a) is dissolved in 15 ml of dichloromethane and 15 ml of ethyl acetate, 450 mg of potassium 2-ethylhexanoate and 60 mg of palladium tetrakistriphenylphosphine are added thereto, and reacted at room temperature for an hour. 150 ml of chloroform is added to the reaction mixture. 50 ml of water is added, and 6N hydrochloric acid is added so that the pH of the aqueous layer becomes 2 followed by washing. After washing with water, it is dried on anhydrous magnesium sulfate, and then concentrated to a small volume. Ether is added thereto, the formed crystals are filtered off, washed with a mixed solution of ether - dichloromethane (4:1) and then dried to obtain 1.36 g of (Z)-2-(2-tritylaminothiazole-4-yl)-2-(4-diphenylmethyloxy-5-p-methoxybenzyloxypyridine-N-oxid-2-yl)methoxyiminoacetic acid. NMR(DMSO-d₆)δ; 3.76(3H,s), 5.01(2H,s), 5.16(2H,s), 6.80(1H,s), 6.96(2H,d), 7.1-7.5(29H,m), 8.06(1H,s) (c) 1.15 g of the above product is dissolved in 30 ml of dichloromethane, then 730 mg of a p-toluenesulfonate salt of p-methoxybenzyl(6R,7R)-7-amino-3-chloromethyl-ceph-3-em-4-carboxylate and 0.54 ml of pyridine are added thereto at -5°C, and stirred for 10 minutes. Thereafter, at -10 to -15°C, 0.14 ml of phosphorus oxychloride is added, and reacted for an hour. After the reaction, 100 ml of ethyl acetate is added followed by washing twice with 50 ml portions of 15% aqueous NaCl. It is dried on anhydrous magnesium sulfate, and then concentrated to dryness to obtain 1.6 g of p-methoxybenzyl(6R,7R)-7-[(Z)-2-(2-tritylaminothiazole-4-yl)-2-(4-diphenylmethyloxy-5-p-methbxybenzyloxypyridine-N-oxid-2-yl)methoxyiminoacetamido]-3-chloromethyl-ceph-2-em-4-carboxylate. NMR(CDCl₃)δ; 3.36(2H,ABq), 3.80(3H,s), 3.83(3H,s), 4.45(2H,ABq), 4.97(1H,d), 5.02(2H,ABq), 5.21(2H, ABq), 5.82(1H,dd), 6.90(4H,m), 7.1-7.5(31H,m), 7.87(1H,s) (d) 265 mg of the 3-chloromethyl compound obtained in (c) is dissolved in 0.55 ml of dimethylsulfoxide, 30 mg of 1-methyl-4-thiopyridone is added thereto, and reacted at room temperature for 1.5 hours. 30 ml of dichloromethane is added to the reaction mixture, which is then washed twice with 10 ml portions of 15% saline. It is dried on anhydrous magnesium sulfate, concentrated to about 3 ml, and added dropwise to 8 ml of ethyl acetate. The formed precipitates are filtered off, and dried to obtain 190 mg of p-methoxybenzyl(6R,7R)-7-[(Z)-2-(2-tritylaminothiazole-4-yl)-2-(4-diphenylmethyloxy-5-p-methoxybenzyloxypyridine-N-oxid-2-yl)methoxyiminoacetamido]-3-(1-methylpyridinium-4-yl)thiomethyl-ceph-3-em-4-carboxylate. It is suspended in 14 ml of anisole, 0.43 ml of trifluoroacetic acid is added, and reacted at room temperature for 30 minutes. The reaction mixture is added dropwise to 6 ml of isopropyl ether, the formed precipitates are filtered off, washed with isopropyl ether, and dried. 135 mg of the obtained precipitates are dissolved in 3 ml of water, and after adding 1 ml of a saturated sodium bicarbonate aqueous solution with ice cooling, stirred for 10 minutes. It is purified by HP-20 column chromatography (eluted with 5% aqueous acetone) to obtain 35 mg of the intended title compound as a sodium salt. NMR(DMSO-d₆)δ; 3.44(2H,ABq), 4.20(3H,s), 4.29(2H,ABq), 5.11(1H,d), 5.29(2H,ABq), 5.75(1H,d), 6.72(1H,s), 7.04(1H,s), 7.62(1H,s), 7.82(2H,d), 8.39(2H,d) Example B (The compound mentioned below is not comprised by the present invention) (6R,7R)-7-[(Z)-2-(2-Aminothiazole-4-yl)-2-(1,5-dihydroxy-4-pyridone-2-yl)methoxyiminoacetamido]-3-(1,2,3-thiadiazole-5-yl)thiomethyl-ceph-3-em-4-carboxylic acid (a) Using 13.29 g of the 1-diphenylmethyloxy-5-p-methoxybenzyloxy-2-hydroxymethyl-4-pyridone obtained in reference example 4, procedures similar to those in Example 21-(a) and (b) are conducted to obtain 19.05 g of (Z)-2-(2-tritylaminothiazole-4-yl)-2-(1-diphenylmethyloxy-5-p-methoxybenzyloxy-4-pyridone-2-yl) methoxyiminoacetic acid. NMR(CDCl₃)δ; 3.75(3H,s), 4.51(2H,s), 5.08(2H,s), 6.33(1H,s), 6.56(1H,s), 6.67(1H,s), 6.79(2H,d), 7.00(1H,s), 7.09(2H,d), 7.2 - 7.4(26H,m) (b) 854 mg of the compound obtained in (a) dissolved in 20 ml of dichloromethane, and 540 mg of a p-toluenesulfonate salt of p-methoxybenzyl(6R,7R)-7-amino-3-chloromethyl-ceph-3-em-4-carboxylate and 0.4 ml of pyridine are added thereto with ice cooling. 0.1 ml of phosphorus oxychloride is added dropwise thereto at -10°C to -15°C, and reacted at the same temperature for 30 minutes. After the reaction, 20 ml of saturated NaCl and 40 ml of ethyl acetate are added, and the organic layer is washed twice with saturated saline. It is dried on magnesium sulfate, and concentrated to dryness under reduced pressure to obtain 1.58 g of a crude powder of p-methoxybenzyl(6R,7R)-7-[(Z)-2-(2-tritylaminothiazole-4-yl)-2-(1-diphenylmethyloxy-5-p-methoxybenzyloxy-4-pyridone-2-yl)-methoxyiminoacetamido]-3-chloromethylceph-3-em-4-carboxylate. (c) The obtained chloromethyl compound is dissolved in 2 ml of dimethylsulfoxide, 175 mg of a sodium salt of 5-mercapto-1,2,3-thiadiazole is added, and reacted at room temperature for an hour. Thereafter, procedures similar to those in Example A-(d) are conducted to obtain 203 mg of the intended title compound as a sodium salt. Compounds of the following Examples 1 and 2 are obtained by treating in a manner similar to that in Example B except that the 5-mercapto-1,2,3-thiadiazole in (c) of Example B is replaced by reagents [A] respectively. Example 1 (6R,7R)-7-[(Z)-2-(2-Aminothiazol-4-yl)-2-(1,5-dihydroxy-4-pyridon-2-yl)methoxyiminoacetamido]-3-(4-hydroxyphenyl)thiomethyl-ceph-3-em-4-carboxylic acid [A] 4-hydroxythiophenol NMR(D₂O)δ; 3.14(1H,d), 3.44(1H,d), 3.66(1H,d), 4.37(1H,d), 4.98(1H,d), 5.26(1H,d), 5.33(1H,d), 5.67(1H,d), 6.69(1H,s), 6.84(2H,d), 7.07(1H,s), 7.37(2H,d), 7.60(1H,s) Example 2 (6R,7R)-7-[(Z)-2-(2-Aminothiazol-4-yl)-2-(1,5-dihydroxy-4-pyridon-2-yl)methoxyiminoacetamido]-3-(4-chlorophenyl)thiomethyl-ceph-3-em-4-carboxylic acid [A] 4-chlorothiophenol NMR(D₂O)δ; 3.15(1H,d), 3.52(1H,d), 3.70(1H,d), 4.44(1H,d), 4.97(1H,d), 5.23(1H,d), 5.34(1H,d), 5.65(1H,d), 6.71(1H,s), 7.10(3H,m), 7.45(2H,m), 7.63(1H,s) Example 3 (6R,7R)-7-[(Z)-2-(2-Aminothiazole-4-yl)-2-(1,5-dihydroxy-4-pyridone-2-yl)methoxyiminoacetamido]-3-hydroxymethyl-ceph-3-em-4-carboxylic acid Sodium(6R,7R)-7-[(Z)-2-(2-aminothiazole-4-yl)-2-(1,5-dihydroxy-4-pyridone-2-yl)methoxyiminoacetamido]-3-acetoxymethyl-ceph-3-em-4-carboxylate (100 mg) is dissolved in 50% aqueous methanol (2 ml), and cooled to - 20°C. 1N-NaOH (0.2 ml) is added and stirred at -20°C to - 25°C for 30 minutes. 1N-NaOH (0.2 ml) is further added, and stirred at the same temperature for an hour. The pH is adjusted to 6 with 1N-HCl, and the methanol is distilled off under reduced pressure. The pH is adjusted to 8 with a saturated sodium bicarbonate aqueous solution, and the solution is purified by HP-20 (70 ml, eluted with water) and LH-20 (50% aqueous methanol) to obtain 54 mg of the intended title compound as a sodium salt. NMR(D₂O)δ; 3.27(1H,d), 3.59(1H,d), 4.27(1H,d), 4.31(1H,d), 5.15(1H,d), 5.25(1H,d), 5.35(1H,s), 5.78(1H,d), 6.73(1H,s), 7.08(1H,s), 7.64(1H,s) Compounds of the following Examples 4 and 5 are obtained treating in a manner similar to that in Example 6 except that the 5-mercapto-1,2,3-thiazole in (d) of Example 6 is replaced by reagents [A] respectively. Example 4 (6R,7R)-7-{(Z)-2-(2-aminothiazole-4-yl)-2-[(RS)-1-(1,5-dihydroxy-4-pyridone-2-yl)ethoxyimono]acetamido}-3-[1-(2-dimethylaminoethyl)-1H-tetrazole-5-yl]thiomethyl-ceph-3-em-4-carboxylic acid [A] 5-mercapto-1-(2-dimethylaminoethyl)-1H-tetrazole NMR(D₂O)δ; 1.61(3H,t), 2,40(3H,s), 2.41(3H,s), 3.10(2H,m), 3.33(1/2H,d), 3.52(1/2H,d), 3.77(1/2H,d), 3.83(1/2H,d), 4.13(1/2H,d), 4.15(1/2H,d), 4.38(1/2H,d), 4.41(1/2H,d), 4.60(2H,m), 5.15(1/2H,d), 5.26(1/2H,d), 5.80(2H,m), 6.63(1/2H,s), 6.73(1/2H,s), 7.04(1H,s), 7.59(1H,s) Example 5 (6R,7R)-7-{(Z)-2-(2-aminothiazole-4-yl)-2-[(RS)-1-(1,5-dihydroxy-4-pyridone-2-yl)ethoxyimono]acetamido}-3-(1,2,4-thiadiazole-5-yl)thiomethyl-ceph-3-em-4-carboxylic acid [A] 5-mercapto-1,2,4-thiadiazole NMR(D₂O)δ; 1.61(3H,t), 3,28(1/2H,d), 3.49(1/2H,d), 3.70(1/2H,d), 3.80(1/2H,d), 4.13(1/2H,d), 4.17(1/2H,d), 4.63(1/2H,d), 4.67(1/2H,d), 5.12(1/2H,d), 5.23(1/2H,d), 5.8-5.9(2H,m), 6.64(1/2H,s), 6.76(1/2H,s), 7.03(1H,s), 7.62(1/2H,s), 7.63(1/2H,s), 8.60(1H,s) Example 6 (6R,7R)-7-{(Z)-2-(2-Aminothiazole-4-yl)-2-[(RS)-1-(1,5-dihydroxy-4-pyridone-2-yl)ethoxyimino]acetamido}-3-(1,2,3-thiadiazole-5-yl)-thiomethyl-ceph-3-em-4-carboxylic acid (a) 2 g of 1,5-di-p-methoxybenzyloxy-2-hydroxymethyl-4-pyridone is dissolved in 50 ml of acetonitrile, 10 g of active manganese dioxide is added, and reacted at 50°C for 3.5 hours. After the reaction, the manganese dioxide is removed by filtration, then washed with acetonitrile, and the filtrate is concentrated under reduced pressure. The residue is dissolved in 100 ml of dichloromethane, washed with water, dried on anhydrous magnesium sulfate, and concentrated under reduced pressure. This is purified by silica gel column chromatography (chloroform - methanol = 50:1) to obtain 1.15 g of 2-formyl-1,5-di-p-methoxybenzyloxy-4-pyridone. NMR(CDCl₃)δ; 3.81(3H,s), 3.82(3H,s), 5.00(2H,s), 5.08(2H,s), 6.72(1H,s), 6.84(2H,d), 6.89(2H,d), 7.05(2H,d), 7.10(1H,s), 7.31(2H,d), 9.60(1H,s) (b) 1.09 g of the formyl compound is suspended in 20 ml of THF, 7.5 ml of a 1M tetrahydrofuran solution of methylmagnesium bromide with ice cooling, and reacted at the same temperature for an hour. 30 ml of a dilute ammonium chloride aqueous solution is added to the reaction mixture, which is then extracted with 120 ml of ethyl acetate. The extract is washed with water, dried on anhydrous magnesium sulfate, and concentrated under reduced pressure. The residue is purified by silica gel column chromatography (chloroform:methanol = 50:1) to obtain 530 mg of 1,5-di-p-methoxybenzyloxy-2-[(RS)-1-hydroxyethyl]-4-pyridone. NMR(CDCl₃)δ; 1.44(3H,d), 3.79(3H,s), 3.80(3H,s), 4.87(2H,ABq), 4.95(1H,q), 5.04(2H,ABq), 6.54(1H,s), 6.80(2H,d), 6.90(2H,d), 6.99(1H,s), 7.21(2H,d), 7.25(2H,d) (c) Using 495 mg of the alcohol compound obtained in (b), procedures similar to those in (a) and (b) of Example 19 are conducted to obtain 320 mg of p-methoxybenzyl(6R,7R)-7-{(Z)-2-(2-tritylaminothiazole-4-yl)-2-[(RS)-1-(1,5-di-p-methoxybenzyloxy-4-pyridone-2-yl) ethoxyimino]acetamido}-3-chloromethyl-ceph-3-em-4-carboxylate. (d) 150 mg of the obtained chloromethyl compound is dissolved in 0.4 ml of dimethylsulfoxide, 30 mg of 5-mercapto-1,2,3-thiadiazole is added, and reacted at room temperature for an hour. Thereafter, procedures similar to those in Example A-(d) are conducted to obtain 51 mg of the intended title compound as a sodium salt. NMR(D₂O)δ; 1.57(3/2H,d), 1.62(3/2H,d), 3.48(1H,ABq), 3.60(1H,ABq), 4.11(1H,ABq), 4.16(1H,ABq), 5.12(1/2H,d), 5.21(1/2H,d), 5.75(1/2H,d), 5.78(1/2H,d), 5.81(1H,q), 6.61(1/2H,s), 6.71(1/2H,s), 7/02(1/2H,s), 7/04(1/2H,s), 7.54(1/2H,s), 7.56(1/2H,s), 8.72(1H,s) Example 7 (6R,7R)-7-{(Z)-2-(2-Aminothiazole-4-yl)-2-[(RS)-1-(1,5-dihydroxy-4-pyridone-2-yl)propoxyimino]acetamido}-3-(1,2,3-thiadiazole-5-yl)-thiomethyl-ceph-3-em-4-carboxylic acid The title compound obtained treating in a manner similar to that in Example 6 except that the methylmagnesium bromide in (b) of Example 6 is replaced by the ethylmagnesium bromide. NMR(D₂O)δ; 1.03(3H,t), 2.00(2H,m), 3.40(1/2H,d), 3.51(1/2H,d), 3.77(1/2H,d), 3.83(1/2H,d), 3.97(1/2H,d), 4.01(1/2H,d), 4.43(1/2H,d), 4.46(1/2H,d) 5.20(1/2H,d), 5.27(1/2H,d), 5.68(1H,m), 5.83(1H,d), 6.61(1/2H,s), 6.72(1/2H,s), 7.08(1H,s), 7.62(1H,s), 8.77(1H,s) Example 8 (6R,7R)-7-{(Z)-2-(2-Aminothiazole-4-yl)-2-[(RS)-1-phenyl-1-(1,5-dihydroxy-4-pyridone-2-yl)methoxyimono]acetamido}-3-(1,2,3-thiadiazole-5-yl)-thiomethyl-ceph-3-em-4-carboxylic acid The title compound obtained treating in a manner similar to that in Example 6 except that the methylmagnesium bromide in (b) of Example 6 is replaced by the phenylmagnesium bromide. NMR(D₂O)δ; 3.10(1/2H,d), 3.15(1/2H,d), 3.51(1/2H,d), 3.64(1/2H,d), 3.97(1/2H,d), 4.02(1/2H,d), 4.25(1/2H,d), 4.31(1/2H,d), 5.07(1/2H,d), 5.12(1/2H,d), 5.68(1/2H,d), 5.73(1/2H,d), 6.68(1/2H,s), 6.76(1/2H,s), 6.82(1/2H,s), 6.95(1/2H,s), 7.11(1/2H,s), 7.12(1/2H,s), 7.40(5H,s), 7.77(1/2H,s), 7.82(1/2H,s), 8.74(1/2H,s), 8.75(1/2H,s) Test Example The compounds (I) of this invention or their salts are novel compounds and exhibit great antibacterial activity which inhibits the growth of pathogenic microorganisms in a wide range covering Gram positive and Gram negative microorganisms. The compounds having a (Z)-2-(2-aminothiazol-4-yl)-2-(1,5-dihydroxy-4-pyridon-2-yl)alkoxyimino group on the 7-position, as compared with the 5-hydroxy-5-pyridon-2-alkoxyimino compounds lacking a hydroxide group on the 1-position (N-position) or the 4,5-dihydroxybenzyloxyimino compounds, exhibit antibacterial power, especially much more excellent antibacterial activity against Gram negative microorganisms including Pseudomonas aeruginosa and further have characteristics of being excellent in solubility in water which is an important requirement for using in injections. As the result of an acute toxicity test on the compounds of this invention using mice, LD50 is 2 g/kg or higher and thus low in toxicity.

Claims: A cephalosporin compound of the formula (I): wherein R¹ is a hydrogen atom, a methyl group, an ethyl group or a phenyl group, provided that, when R¹ is a hydrogen atom, A is a hydroxy group, a phenylthio group, a halogen- or a hydroxy-substituted phenylthio group; and, when R¹ is a methyl group, an ethyl group or a phenyl group, A is a tetrazolylthio group, a (C₁₋₃)alkyl- or a di(C₁₋₃) alkylamino(C₁₋₃)alkyl-substituted tetrazolylthio group, a thiadiazolylthio group, or a (C₁₋₃)alkyl-substituted thiadiazolylthio group, or pharmacologically acceptable salt thereof. A compound according to claim 1, which is (6R,7R)-7-{(z)-2-(2-aminothiazol-4-yl)-2-[(RS)-1-(1,5-dihydroxy-4-pyridon-2-yl)ethoxyimino]acetamido}-3-(1,2,3-thiadiazol-5-yl)thiomethyl-ceph-3-em-4-carboxilic acid. A compound according to claim 1, which is (6R,7R)-7-{(z)-2-(2-aminothiazol-4-yl)-2-[(RS)-1-(1,5-dihydroxy-4- pyridon-2-yl)ethoxyimino]acetamido}-3-(1,2,4-thiadiazol-5-yl)thiomethyl-ceph-3-em-4-carboxilic acid. A compound according to claim 1, which is (6R,7R)-7-{(z)-2-(2-aminothiazol-4-yl)-2-[(RS)-1-(1,5-dihydroxy-4-pyridon-2-yl)propoxyimido]acetamido}-3-(1,2,3-thiadiazol-5-yl)thiomethyl-ceph-3-em-4-carboxilic acid. A compound according to claim 1, which is (6R,7R)-7-{(z)-2-(2-aminothiazol-4-yl)-2-[(RS)-1-phenyl-1-(1,5-dihydroxy-4-pyridon-2-yl)methoxyimino]acetamido}-3-(1,2,3-thiadiazol-5-yl)thiomethyl-ceph-3-em-4-carboxilic acid. An antibacterial agent which contains a cephalosporin compound of the formula (I): wherein R¹ is a hydrogen atom, a methyl group, an ethyl group or a phenyl group, provided that, when R¹ is a hydrogen atom, A is a hydroxy group, a phenylthio group, a halogen- or a hydroxy-substituted phenylthio group; and, when R¹ is a methyl group, an ethyl group or a phenyl group, A is a tetrazolylthio group, a (C₁₋₃)alkyl- or a di(C₁₋₃) alkylamino(C₁₋₃)alkyl-substituted tetrazolylthio group, a thiadiazolylthio group, or a (C₁₋₃)alkyl-substituted thiadiazolylthio group, or pharmacologically acceptable salt thereof.

Inventors: IWAMATSU KATSUYOSHI PHARMACEUT, KATANO KIYOAKI PHARMACEUTICAL, KONDO SHINICHI PHARMACEUTICAL, NAKABAYASHI SATORU PHARMACEUTI, OGINO HIROKO PHARMACEUTICAL RE, SEZAKI MASAJI PHARMACEUTICAL R, TSURUOKA TAKASHI PHARMACEUTICA, YOSHIDA TAKASHI PHARMACEUTICAL, IWAMATSU, KATSUYOSHI PHARMACEUTICAL RES.LAB., KATANO, KIYOAKI PHARMACEUTICAL RES.LAB., KONDO, SHINICHI PHARMACEUTICAL RES.LAB., NAKABAYASHI, SATORU PHARMACEUTICAL RES.LAB., OGINO, HIROKO PHARMACEUTICAL RES.LAB., SEZAKI, MASAJI PHARMACEUTICAL RES.LAB., TSURUOKA, TAKASHI PHARMACEUTICAL RES.LAB., YOSHIDA, TAKASHI PHARMACEUTICAL RES.LAB.
Applicants: MEIJI SEIKA KAISHA, ZAIDAN HOJIN BISEIBUTSU, MEIJI SEIKA KAISHA LTD., ZAIDANHOJIN BISEIBUTSU KAGAKU KENKYUKAI
Application year: 1988
Main classification: C07D501
IPC codes: C07D501