1-OXA-1-DETHIA-CEPHALOSPORIN COMPOUNDS AND ANTIBACTERIAL AGENT COMPRISING THE SAME

Abstract: The subject invention includes 1-oxa-1-dethia-­ cephalosporin compounds represented by the general for­ mula: wherein R¹ is a group of the formula: where R⁴ is loweralkyl (1-6 carbons) including a methyl group or an ethyl group, or R¹ is a group of the formula: where R⁵ is a hydrogen atom, a 4-ethyl-2,3-dioxopiperazin-­ 1-yl group or a 5- or 6-membered heterocyclic ring having 2 nitrogen atoms at the sole hetero substituent in the ring and having at least one hetero group on the carbon adjacent to the ring nitrogens, and the carbon atom to which the asterisk is attached shows (R)-configuration or (S)-­ configuration or a mixture of these configurations; both of R² and R³ are each a hydrogen atom and the other a methyl group, and a pharmaceutically acceptable hydrate, salt of ester thereof. These compounds are useful as antibacterial agents.

Description: TITLE OF THE INVENTION NEW l-OXA-l-DETHIA-CEPHALOSPORIN COMPOUNDS AND ANTIBACTERIAL AGENT COMPRISING THE SAME DETAILED DESCRIPTION OF THE INVENTION This invention relates to a novel antibacterial l-oxa-l-dethiacephalosporin compound. We, the present inventors, have made extensive researches in an attempt to seek for and to synthesize such a new cephalosporin compound which exhibits a wide range of antibacterial spectrum and which is active against a variety of resistant bacteria. As a result, the present inventors have now succeeded in preparing l-oxa-l-dethiacephalosporin compounds which are effective as an antibacterial agent in therapeutic treatment of animals including man. Thus, the present inventors have succeeded in the synthesis of a l-oxa-l-dethiacephalosporin compound of the general formula (I) EMI2.1 wherein R1is a group of the formula: EMI2.2 where R4 is a methyl group or an ethyl group, or R1 is a group of the formula: EMI2.3 where R5 is a hydrogen atom, a 4-ethyl-2,3dioxopiperazin-l-yl group or a 5- or 6-membered heterocyclic radical having 2 ring nitrogens as the sole hetero substituent in the ring and having at least one hetero group on the carbon adjacent to the ring nitrogens of the formula: EMI3.1 and the carbon atom to which the asterisk is attached shows (R)-configuration or (S)-configuration or a mixture of these configurations; both of R2 3 and R3 are each a hydrogen atom, or either one of R2 and R3 is a hydrogen atom and the other a methyl group. And, we have found that the l-oxo-l-dethia-cephalosporin compounds bearing a (2,5-dihydro-6-hydroxy-2-methyl-5-oxo-1,2,4-triazin- 3-yl) thiomethyl group at the 3-position thereof show a wide range of antibacterial activity against gram-positive and gram-negative bacteria, including a variety of resistant bacteria, and that these compounds exhibit an excellent activity as an antibacterial agent when administered intramuscwlarly or intravenously to the animals. Japanese patent application first publication "KOKAI" No. 154980/80 discloses such cephalosporin compounds which have at the 3-position thereof a (2,5-dihydro-6-hydroxy-2-methyl-5-oxo l,2,4-triazin-3-yl) thiomethyl group, but this first publication has no description in respect of the l-oxa-l-dethia-cephalosporin compounds. The compounds of the formula (I) mentioned above are thus novel compounds. It is know that generally, such l-oxa-l-dethia-cephalosporin compounds having a 2-aminothiazol-4-acetic acid derivative as a substituent on the 7-amino group thereof are inferior in the antibacterial activity to the corresponding cephalosporins (R.B. Molin, M. Gorman "Chemistry and Biology of B-lactam Antibiotics" 2, pages 1-98 (1982), Academic Press, New York). While, the present inventors have found that though the compound of the general formula (I) according to this invention has a 2-aminothiazol-4-acetic acid derivative as a substituent on the 7-amino group, the new compound of this invention exhibits an excellent inhibitory activity to Staphylococcus faecalis against which the corresponding cephalosporins (as referred to in said Japanese patent application first publication "KOKAl" No. 154980/80) are ineffective, and that the antibacterial activity of the l-oxa-l-dethiacephalosporin compounds of the formula (I) can be further enhanced by introducing a methyl group into the 2-position thereof and by appropriately selecting the substituent R4 (R4is either methyl group or ethyl group) in the compounds of the formula (I). In this way, the invention have been accomplished. According to a first aspect of this invention, therefore, there is provided a l-oxa-l-dethiacephalosporin compound of the general formula (I) mentioned above, and a pharmaceutically acceptable hydrate, salt or ester thereof. Typical examples of the compounds of the general formula (I) include the following: No. 1 (6R,7R)-7[(Z)-2-(2-aminothiazol-4-yl)-2 (methoxyimino)acetamido]-(2S)-2-methyl-3-(2,5- dihydro-6-hydroxy-2-methyl-5-oxo-1,2,4 triazin-3-yl) thiomethyl-l-oxa-1-dethia-ceph-3- em-4-carboxylic acid of the formula EMI5.1 No. 2 (6R, 7R) -7- [ (Z) -2- (2-aminothiazol-4-yl) -2- (ethoxyimino)acetamido]-(2S)-2-methyl-3-(2,5- dihydro-6-hydroxy-2-methyl-5-oxo-1,2,4 triazin-3-yl) thiomethyl-l-oxa-l-dethia-ceph- 3-em-4-carboxylic acid of the formula EMI6.1 No. 3 (6R, 7R)-7-[(Z)-2-(2-aminothiazol-4-yl)-2 (methoxyimino)acetamido]-3-(2,5-dihydro-6 hydroxy-2-methyl-5-oxo-l,2,4-triazin-3-yl) thiomethyl-l-oxa-l-dethia-ceph-3-em-4 carboxylic acid of the formula EMI6.2 No. 4 (6R, 7R)-7-[(Z)-2-(2-aminothiazol-4-yl)-2 (ethoxyimino)acetamido]-3-(2,5-dihydro-6 hydroxy-2-methyl-5-oxo-l,2,4-triazin-3-yl) thiomethyl-l-oxa-l-dethia-ceph-3-em-4 carboxylic acid of the formula EMI7.1 No. 5 (6R,7R)-7-[2-(2-aminothiazol-4-yl)-2-(4 ethyl-2,3-dioxo-1-piperadinecarboxamido) acetamidol-(2S)-2-methyl-3-(2,5-dihydro-6 hydroxy-2-methyl-5-oxo-l,2,4-triazin-3-yl) thioylmethyl-l-oxa-l-dethia-ceph-3-em-4 carboxylic acid of the formula EMI7.2 No. 6 (6R,7R)-7-[2-(2-aminothiazol-4-yl)-2-(form- amido)acetamido]-(2S)-2-methyl-3-(2,5-dihydro 6-hydroxy-2-methyl-5-oxo-1,2,4-triazin-3-yl) thiomethyl-l-oxa-l-dethia-ceph-3-em-4 carboxylic acid of the formula EMI8.1 No. 7 (6R, 7R)-7-[(Z)-2-(2-aminothiazol-4-yl)-2 2,3-dioxo-1-piperadine-carboxamido)acetamido] 3-(2,5-dihydro-6-hydroxy-2-methyl-5-oxo-1,2,4 triazin-3-yl)-thiomethyl-1-oxa-1-dethiaceph 3-em-4-carboxylic acid of the formula EMI8.2 No. 8 (6R,7R)-7-[2-(2-aminothiazol-4-yl)-2-(form amido)acetamido)-3- (2,5-dihydro-6-hydroxy-2- methyl-5-oxo-l,2,4-triazin-3-yl) thiomethyl- l-oxa-l-dethia-ceph-3-em-4-carboxylic acid of the formula EMI9.1 The above-mentioned compound number are referred to in Tables and Examples given hereinafter. The compound of the general formula (I) according to this invention includes a solvate, particularly hydrate of said compound (I). Moreover, this invention also covers a non-toxic salt and a non-toxic ester of the compound of the formula (I), and in particular, a metabolically unstable ester thereof, as will be described later. By the term "non-toxic" is meant "pharmaceutically acceptable." The above-exemplified representatives of the novel compounds of the formula (I) according to this invention have the following advantages; (a) As will be clear from Table I given below which shows antibacterial spectra of the test compounds No. 1 to No. 8 against a variety of gram-positive and gram-negative bacteria as determined in vitro in term of the minimum inhibitory concentration (MIC) of said test compounds against said bacteria, the compounds of this invention exhibit a high antibacterial activity against a wider range of bacteria. For comparison, MIC of Latamoxef and Ceftriaxone are also indicated in the Table 1. As be apparent from the Table I, not only the compounds of this invention exhibit a practically effective, high antibacterial activity against a variety of bacteria, including the resistant strains thereof, but also those compounds as indicated in Examples 1, 2, 5 and 6 in particular, show such a remarked advantage that they are effective against Streptococcus faecalis. Besides, the compounds of Examples 1, 2, 4, 5 and 7 advantageously are also effective against Pseudomonas aeruginosa. Furthermore, the compound of the formula (I) according to this invention has an advantage that it provides a higher level of the antibacterial activity and a higher concentration of the compound in blood serum as well as a longer durability of the blood serum concentrated, as compared to such l-oxa-ldethia-cephalosporin derivatives which are disclosed in the specification of Japanese patent application first publication "KOKAI" No. 46287/84 invented by the same inventors as of the present invention. Table 1 Minium inhibitory concentration (MIC) Test Organism Compound Compound Compound Compound Compound Compound Compound Compound Latamoxef Ceftriaxone No. 1 No. 2 No. 3 No. 4 No.5 No. 6 No. 7 No. 8 (comparative) (comparative) Staphylococcus 1.56 1.56 0.78 1.56 3.13 1.56 1.56 1.56 3.13 3.13 aureus Smith Staphylococcus 0.78 1.56 0.78 0.78 1.56 0.78 0.78 1.56 3.13 1.56 aureus 209 p JC-1 Escherichia coli 0.10 0.39 0.10 0.10 0.10 0.10 0.05 1.10 0.10 0.10 MIMJ JC-2 Escherichia coli 0.78 0.78 3.13 1.56 1.56 1.56 1.56 1.56 0.39 0.78 GN206 Salmonella 0.05 0.39 0.05 0.10 0.025 0.10 0.025 0.05 0.05 3.13 typhimurium LI-2 Proteus mirabilis 0.025 0.20 0.05 0.025 0.78 0.10 50 0.10 0.10 0.025 GN79 Proteus vulgaris 0.10 0.20 0.10 1.05 0.025 50 0.025 100 0.20 0.025 GN76 Prorteus rettgeri 0.78 0.76 0.29 0.39 0.78 0.10 0.39 0.10 0.05 0.025 GN624 Seratia marcescens 0.39 0.39 0.39 - 0.39 0.20 0.20 0.20 0.10 0.10 No. 2 Table 1 (Cont'd) Minium inhibitory concentration (MIC) Test Organism Compound Compound Compound Compound Compound Compound Compound Compound Latamoxef Ceftriaxone No. 1 No. 2 No. 3 No. 4 No.5 No. 6 No. 7 No. 8 (comparative) (comparative) Pseidomonas 6.25 12.5 25 6.25 3.13 100 12.5 100 6.25 50 aeruginosa M833833 " M833829 6.25 6.25 12.5 - 1.56 50 12.5 100 12.5 12.5 " E-2 12.5 25 50 25 3.13 100 25 100 6.25 100 Streptococcus 6.25 1.56 12.5 25 50 12.5 0.18 25 25 3.13 faucalis ATCC8043 " W-73 50 50 50 100 25 100 100 100 100 100 " W-74 6.25 6.25 50 - 6.25 50 25 50 100 100 " W-75 0.20 0.20 0.39 0.20 3.13 6.24 12.5 6.24 100 1.56 (b) The novel compounds of this invention have such a pharmacological merit that they show an enhanced maximum of the compound concentration in serum and a longer durability of the compound concentration in serum after the administration. In order to demonstrate experimentally these merits the novel compound was given at a dosage of 25 mg/kg subcutaneously to mice (three mice in each group, average body weight 20 g), and blood was sampled regularly from the animals. For the serum which was separated from the blood samples, the concentration in the serum of the compound administered was bioassayed using Escherichia coli as assay microorganism. The test results obtained are shown in Table 2 below: TABLE 2 Concentration in serum (mcg/ml) Compound Tested 1/12 1/4 1/2 1 hour Compound No. 1 27 47.7 41 24.8 Compound No. 5 24 44 25 10 Compound No. 7 25 34 32 13 As demonstrated by the foregoing tests (a) and (b), the novel compound of the formula (I) according to this invention has remarkably excellent properties as the antibacterial agent, so that it is a useful antibiotic which can be administered orally or parenterally for curative or preventative treatment of bacterial infections in mammalian animals, including man. Improved duration of the compound concentration in blood as described above is an important factor by which the antibacterial activity in vitro can be developed in vivo. According to a second aspect of this invention, therefore, there is provided an antibacterial agent which comprises at least one of a l-oxa-l-dethia-cephalosporin compound represented by the aforesaid general formula (I), and a non-toxic hydrate, a non-toxic salt or a non-toxic ester of said compound as the active ingredient. Non-toxic salt, that is, the pharmaceutically acceptable salt of the compound of general formula (I) includes conventional non-toxic salts (carboxylate) which may be formed by reaction of the carboxyl group present in said compound with a base, especially such salts with an inorganic base, for example, alkali metal salts such as sodium or potassium salt and alkaline earth metal salts such as calcium, magnesium or zinc salt; such addition salts with a basic amino acid, for example, lysine, arginine, ornithine or histidine; and such addition salts with an organic amine salt or other basic salts which will normally form a salt with cephalosporin. Other non-toxic salts of the compound (I) according to this invention include those which may be formed by addition to the amino group or other basic group of an inorganic acid such as hydrochloric, hydrobromic, sulfuric, nitric or phosphoric acid, of an organic carboxylic acid or organic sulfonic acid such as trifTvoroacetic, benzenesulfonic, methanesulfonic, maleic, tartaric or p-toluenesulfonic acid, and of an acidic amino acid such as aspartic or glutamic acid, and further they may include intermolecular or intramolecular salts. The non-toxic esters of the compound (I) according to this invention include those of the carboxyl group present in said compound with a pharmaceutically acceptable ester-forming group. Among them are preferred such metabolically unstable esters, which carry an ester-forming group cleavable upon hydrolysis in vivo. Examples of such ester-forming group include acetoxymethyl, pivaloyloxymethyl, a-ethoxycarbonyloxyethyl, phthalidyl and phenyl groups and the like. For use as antibacterial agent, the compound (I) of this invention may be given orally or parenterally to adult at a unit dosage of 50 to 1500 mg and preferably of 100 to 1000 mg once to five times per day when it is administered for therapeutic treatment of bacterial infections in man. The antibacterial agent according to this invention may usually be composed of the compound of this invention in association with a pharmaceutically acceptable carrier such as a solid or liquid excipient, and it may be formulated into solid preparations such as tablets, capsules, powder and pre-treated powder, or into liquid preparations such as injectable solution, intravenous drip solution, suspension and syrup. Solid or liquid excipient used for this purpose may be any one known in this field of the art. As stated above, the preparations so formed may preferably contain the compound of this invention at an amount required for the unit dosage of the compound for adult indicated above. The compound (I) according to this invention may be produced, for example, by reacting a l-oxa-l-dethia-cephem compound of the general formula (IIa) EMI16.1 wherein both of R2 and R3 are each a hydrogen atom, or either one of R2 and R4 is a hydrogen atom and the other a methyl group, R6 is a carboxyl-protecting group, and X is a chlorine, bromine or iodine atom, with a carboxylic acid of the general formula (III) R1COOH (III) wherein R1 is as defined in the general formula (I) hereinbefore, or with a functional derivative thereof, to give a 7-N-acylation product of the general formula (IV) EMI16.2 wherein Rl, R2, R3, R6 and X are as defined above, and reacting the resultant 7-N-acylated compound of the formula (IV) with 2,5-dihydro-6 hydroxy-2-methyl-5-oxo-3-mercapto-l,2,4-triazin of the formula (V) EMI17.1 preferably in the presence of a base which acts as binding agent of hydrogen halide, for example an alkyl amine, to give a compound of the general formula (VI) EMI17.2 wherein R1, R2, R3 and R6 are as defined hereinabove, followed by removal in a conventional manner of the remaining protecting groups from the resultant compound of the formula (VI) above. The steps in the process for the synthesis of the compound of the general formula (I) from the compound of the general formula (II) are described below; In order to introduce a desired acyl group to the 7-amino group of the compound (it), the compound of the formula (II) is at first reacted with the carboxylic acid of the formula (III) to effect the acylation on the 7-amino group, and thereby to obtain the 7-N-acylated product of the formula (IV). This acylation reaction may be carried out in a conventional manner known per se. The carboxylic acid of the formula (III) may preferably be used in the form of a functional derivative of said carboxylic acid such as an acid halide, an active acid ester, an acid anhydride or a mixed acid anhydride thereof. The acylation reaction may also be performed using the carboxylic acid of the formula (III) which has not been activated as above, when the reaction may be carried out by a dehydration condensation method with carbodiamido or by a phosphorous oxychloride method. The acylation may generally be performed in an organic solvent which is inert to the reaction such as dioxane, tetrahydrofuran, dimethylformamide, methylene chloride, chloroform or ethyl acetate, at a temperature of -500C to +500C. Next, the 7-N-acylated product of the formula (IV) is reacted with 2,5-dihydro-6-hydroxy-2 methyl-5-oxo-3-mercapto-l,2,4-triazin (V) as the reagent to introduce a desired substituent for the 3'-halogen atom, whereby to obtain the compound (VI). This replacement reaction at the 3'-position is itself a known reaction which is disclosed in the specification of Japanese patent application first publication "KOKAI" No. 154980/80. The compounds (IV) and (V) are mixed with each other in an inert organic solvent, preferably in dimethylformamide (DMF), dimethylacetoamide or dioxane, at OOC to 800C to effect the reaction. In case the compound of the formula (IV) where X is a chlorine atom, 1 - 2 equivalent of sodium iodide (NaI) may preferably be added to the reaction system to ensure that the reaction proceeds in a higher yield. Removal of the remaining protecting group from the compound (VI) gives the compound of the general formula (I) according to this invention. The protecting groups which are remaining in the compound (VI) are the carboxyl-protecting group on the 4-carboxyl group and the amino-protecting group on the 2-amino group of the 2-aminothiazol side chain at the 7-position of the 1-oxacepham ring. These protecting groups may be removed successively or simultaneously in a conventional manner. In case R6 is a diphenylmethyl group or p-nitrobenzyl group and 2-amino group of the 2-aminothiazol moiety has been protected with trityl group, these protecting groups are removed simultaneously by such a method as catalytic reduction or hydrolysis with an acidic reagent. The deprotection reaction for this purpose is known and performed in a conventional manner using an acidic reagents, for example, a mineral acid such as hydrochloric acid, an organic acid such as trifluoroacetic acid, or a Lewis acid such as aluminum chloride. The compound of the general formula (IIa) employed as a starting material for the process of producing the compound (I) of this invention may be prepared by the following reaction flow sheet: EMI20.1 In this reaction flow sheet, R2, R , R and X denote the same meaning as defined hereinbefore. The compound of the formula (VII) which is used as a starting material for the preparation of the compound (IIa) showm in the above reaction flow sheet and in which either one of RÚ and Rê is a methyl group may be synthesized according to the method as disclosed in Japanese patent application first publications "KOKAI" No. 46287/84 and No. 51291/84 each invented by some of the present inventors. The compound (VII) where R1 and R2 each is a hydrogen atom is a known compound which is disclosed in Japanese patent application first publications "KOKAI" No. 3088/79 and No. 25551/78. In these Formulas in the reaction flow sheet shown above, R6 is a carboxyl-protecting group which may generally be used for penicillins, cephalosporins and l-oxa-l-dethiacephalosporins. These carboxylprotecting groups may preferably be an alkyl group such as l-butyl group, dichloroethyl group and trichloroethyl group; and an aralkyl group such as benzyl group, p-nitrobenzyl group, p-methoxybenzyl group, phenacylmethyl group and diphenylmethyl group. Among these protecting groups, preferred are ones which are easily removed under a reductive condition, for example, diphenylmethyl group and p-nitrobenzyl group. In the first step for the preparation of the compound (IIa), the starting compound (VII) is formylated so that the 7-amino group is protected and the compound (VIII) is formed. This formylation reaction may be carried out in a conventional manner, when it is convenient to use a mixture of formic acid and-. acetic anhydride or an active ester of formic acid, preferably trichlorophenylester of the formula: EMI22.1 Thus, the 7-N-formylated product (VIII) is obtained. Solvents used in the formulation may be an ordinary organic solvent, particularly an inert organic solvent which may preferably be methylene chloride, chloroform, tetrahydrofuran, dioxane and the like. In the next 2nd step, the 3-N-methyltetrazol group of the compound (VIII) is reductively removed to give the 3-methyleno-l-oxacepham compound of the formula (IX). The reduction may be carried out at -50C to 500C in an inert solvent in the presence of an organic or inorganic acid as the hydrogen source and using a metal powder such as zinc, iron, magnesium and the like. The reduction is preferably performed in methylene chloride or dioxane using zinc or magnesium in the presence of formic acid or acetic acid. In the 3rd step, the compound (IX) is treated with a halogenating agent to give a corresponding 3-halogenomethyl compound (X). Such compound of the formula (X) where either of R2 and R3 is a methyl group is a novel compound, while usual cephalosporin compound and such compound of the formula (X) where R2 and R3 each is a hydrogen atom are known compounds. The halogenation of the compounds (IX) may be performed according to the halogenation procedure as described in "Journal of American Chemical Society", 99, 2822 (1977), and "Tetrahedron", 39, No. 15, 2515-2526 (1983). For the halogenation, the compound (IX) may be reacted with bromine or iodine, preferably in the presence of organic base DBU to give a 3-bromomethyl compound (X) (X=Br) and a 3-iodomethyl compound (X) (X=I), respectively. A 3-chloromethyl compound (X) (X=C1) may be obtained by reacting the compound (IX) with phenylselenyl chloride, followed by oxidative deselenylation of the resultant 3-phenylseleno-loxacepham compound. In the fourth step, the formyl group for the 7-amino-protecting group of the compound (X) is removed to give the compound of the formula (I Ia). Deformulation by acid treatment is a well-known reaction, and to this end anhydrous hydrochloric acid is preferred to ensure that the deformulation can be performed selectively without affecting the other protecting group which is present in the molecule and unstable to the acid, that is, the protecting group for the 4-carboxylic group of said compound (X). The deformulation may be carried out with 2-8 equivalents of anhydrous hydrochloric acid in an inert solvent at a temperature of -50C to +200 C. Depending on the procedure employed after the deformulation reaction, the compound of the general formula (IIa) is isolated either in the form of its free base or in the form of its hydrochloride. Thus, according to a third aspect of this invention, there is provided, as an important intermediate product, a l-oxa-l-dethiacephem compound of the general formula (IIb) EMI24.1 wherein either Ra is a hydrogen atom and Rb is a methyl group, or Ra is a methyl group and Rub is a hydrogen atom, X is a chlorine atom, a bromine atom or an iodine atom, and R7 is a hydrogen atom or a carboxyl-protecting group, which compound is a novel compound, among the compounds of the general formula (IIa). This invention is now illustrated with reference to the following Examples. EXAMPLE 1 (1) Production of diphenylmethyl 7ss-formamido-2ss- methyl-3- (l-methyl-lH-tetrazol-5-yl) thiomethyl-l-oxa-l- dethia-3-cephem-4-carboxylate of the formula: EMI24.2 wherein Me is a methyl and Ph is a phenyl group, and also hereinafter as otherwise stated. Diphenylmethyl 7ss-amino-2ss-methyl-3 (l-methyl-lH-tetrazol-5-yl)thiomethyl-1-oxa-1-dethia-3- cephem-4-carboxylate (800 mg) and 440 mg of 2,4,5trichlorophenyl formate were dissolved in 40 ml of methylene chloride, and the solution was allowed to stand at ambient temperature for 20 hours and then concentrated. The residue was washed with ethyl acetate and recrystallized from methylene chloride to give 664 mg (yield: 79%) of the titled compound. IR (Nujol), max (cm1): 1779, 1722, 1662 NMR(CDCl3), (ppm): 1.55 (3H, d, J = 6.6 Hz), 3.82 (3H, s), 4.73, 4.05 (2H, ABq, J = 13.7 Hz), 4.89 (1H, q, J = 6.6 Hz)), 5.11 (1H, d, J = 3.9 Hz), 5.76 (1H, dd, J = 9.5, 6.5 Hz), 6.89 (1H, s), 7.10-7.70 (10H, m), 8.28 (1H, s) (2) Production of diphenylmethyl 7ss-formamido-2ss- methyl-l-oxa-l-dethia-3-methylenecepham-4-carboxylate of the formula: : EMI25.1 The product from the step (1) above, that is, diphenylmethyl 7ss-formamido-2ss-methyl-3- (l-methyl-lH-tetrazol-5-yl) thiomethyl-l-oxa-l-dethia-3- cephem-4-carboxylate (370 mg) was dissolved in 7 ml of methylene chloride, to which were added 2.0 ml of acetic acid and 170 mg of magnesium (metal). The mixture obtained was agitated at ambient temperature for 40 hours and filtered. The filtrate so obtained was concentrated. The residue obtained was dissolved in ethyl acetate, washed with saturated aqueous sodium bicarbonate and then with water, dried over MgSO4 and concentrated. The residue was purified by column chromatography on silica gel, to give 166 mg (58%) of the titled compound. IR (CHCl3), max(cm-Ú): 1780, 1741, 1695 NMR(CDC13), (ppm): 1.37 (3H, d, J = 6.3 Hz), 4.37 (1H, q, J = 6.3 Hz), 5.13 (1H, s), 5.29 (1H, s), 5.36 (1H, s), 5.41 (1H, d, J = 3.5 Hz), 5.61 (1H, dd, J = 10.1, 3.5 Hz), 6.20 (1H, d, J = 10.1 Hz), 6.85 (1H, s), 7.10-7.40 (10H, m), 8.19 (1H, s). (3) Production of diphenylmethyl 7ss-formamido-2ss- methyl-3-chloromethyl-1-oxa-1-dethia-3-cephem-4carboxylate of the formula: EMI26.1 The product from the step (2) above, that is, diphenylmethyl 7R-formamido-2n-methyl-l-oxa- l-dethia-3-methylenecepham-4-carboxylate (300 mg) and 280 mg of phenylselenyl chloride were dissolved in 8 ml of methylene chloride, and the solution was agitated at ambient temperature for 5 hours. 40% Aqueous peracetic acid (300 mg) was added under ice-cooling to said solution, followed by agitation at ambient temperature for 30 minutes. The resultant reaction solution was washed with saturated aqueous sodium bicarbonate, with aqueous sodium thiosulfate and then with water, dried over MgSO4 and concentrated. The residue was purified by column chromatography on silica gel to afford 250 mg (77%) of the titled compound. IR (CHC13), max (cm l):1797, 1723, 1697 NMR (CDC13), (ppm): 1.51 (3H, d, J = 6.6 Hz), 4.11, 5.16 (2H, ABq, J = 12.5 Hz), 4.78 (1H, q, J = 6.6 Hz), 5.12 (1H, d, J = 3.7 Hz), 5.77 (1H, dd, J = 9.9, 3.7 Hz), 6.28 (1H, d, J = 9.9 Hz), 6.90 (1H, s), 7.10-7.60 (10H, m), 8.24 (1H, s) (4) Production of diphenylmethyl 7ss-amino-2ss- methyl-3-chloromethyl-l-oxa-l-dethia-3-cephem-4carboxylate of the formula: : EMI27.1 The product from the step (3) above, that is, diphenylmethyl 7ss-formamido-2ss-methyl-3-chloromethyl-l-oxa-l-dethia-3-cephem-4-carboxylate (200 mg) was dissolved in 2 ml of methanol. The solution was admixed with 75 l of a solution of 6N-HC1 in dioxane, agitated at ambient temperature for 30 minutes and concentrated. The residue was washed with ether and dried to give 200 mg (a quantitative yield) hydrochloride of the titled compound. The free base of the title compound shows the following physico-chemical properties: IR (CHC13), max(cm ): 1783, 1720 NMR (CDC13), (ppm): 1.52 (3H, d, J = 6.7 Hz), 1.85 (2H, s), 4.11, 5.15 (2H, ABq, J = 12.8 Hz), 4.49 (1H, d, J = 4.0 Hz), 4.77 (1H, q, J = 6.8 Hz) 5.04 (1H, d, J = 4.0 Hz), 6.90 (1H, s), 7.10-7.60 (10H, m) (5) Production of disodium (6R, 7R)-7[(Z)-2-(2- aminothiazol-4-yl)-2-(methoxyimino)acetamido]-(2S)-2- methyl-3-(2,5-dihydro-6-hydroxy-2-methyl-5-oxo-l,2,4- triazin-3-yl) thiomethyl-l-oxa-l-dethia-3-cephem-4-car- boxylate (disodium salt of compound No. 1) of the formula: : EMI28.1 (a) (Z)-2-(2-Tritylaminothiazol-4-yl)-2-methoxyimino-acetic acid (108 mg) and 100 mg of diphenylmethyl 7ss-amino-2ss-methyl-3-chloromethyl-1-oxo-1dethia-3-cephem-4-carboxylate hydrochloride as obtained in the step (4) above were dissolved in 3 ml of methylene chloride. To the solution at -200C were added 87 ul of pyridine and 29 p1 of phosphorous oxychloride, and the mixture was agitated at the same temperature as above for 30 minutes and further under ice-cooling for 30 minutes to effect the acylation. The reaction solution was washed with ice-water, with saturated aqueous sodium bicarbonate and then with water, dried over MgSO4 and concentrated. The residue obtained was purified by column chromatography on silica gel developed with a development solvent of toluene-ethyl acetate (5:1) to give 140 mg (75%) of diphenylmethyl 76-[(Z)-2-(2- tritylamino-thiazol-4-yl)-2-(methoxyimino)acetoamido3- 2ss-methyl-3-chloromethyl-1-oxa-1-dethia-3-cephem-4- carboxylate of the formula: EMI29.1 wherein Tr is trityl group. NMR (CDCl3), (ppm):1.48 (3H, d, J = 6.8 Hz), 4.10, 5.18 (2H, ABq, J = 12.3 Hz), 4.05 (3H, s), 4.77 (1H, q, J = 6.8 Hz), 5.13 (1H, d, J = 3.9 Hz), 5.77 (1H, dd, J = 3.8, 10.5 Hz), 6.80 (1H, s), 6.89 (1H, s), 7.10-7.90 (25H, m) (b) The product (140 mg) from the step (a) above, 36 mg of 2,5-dihydro-6-hydroxy-2-methyl-3 mercapto-5-oxo-1,2,4-triazine.sodium salt, 25 mg of sodium iodide were dissolved in 1 ml of DMF, and the solution was agitated at ambient temperature for 1 hour to effect the replacement reaction. The reaction solution was diluted with 6 ml of ethyl acetate, washed with acidified water (pH 3.0) and then with water, dried over MgSO4 and concentrated. The residue was subjected to column chromatography on silica gel developed with a development solution of chloroform-methanol (20:1) to give 130 mg (81%) of diphenylmethyl 7ss-[(Z)-2-(2- tritylaminothiazol-4-yl)-2-(methoxyimino)acetoamido] 2ss-methyl-3-(2,5-dihydro-6-hydroxy-2-methyl-5-oXo- 1,2,4-triazin-3-yl)thiomethyl-1-oxa-1-dethia-3-cephem4-carboxylate of the formula: EMI30.1 NMR (CDC13), (ppm): : 1.50 (3H, d, J = 6.9 Hz), 3.59 (3H, s), 4.06 (3H, s), 4.08, 4.50 (2H, ABq, J = 13.0 Hz), 4.72 (1H, q, J = 6.8 Hz), 5.12 (1H, d, J = 3.8 Hz), 5.73 (1H, dd, J = 3.8, 10.3 Hz), 6.77 (1H, s), 6.92 (1H, s), 7.10-7.80 (25H, m) (c) The product (120 mg) from the step (b) above was added to a mixture of ice-cooled trifluroacetic acid (1.2 ml) and anisol (0.2 ml). The resulting mixture was agitated for 30 minutes at the same temperature as above under ice-cooling to effect the deprotection, and to the reaction solution was added 6 ml of isopropylether (IPE) to deposit a precipitate. The precipitate (70 mg) obtained by filtration and 30 mg of sodium bicarbonate were taken up into 1 ml of water and purified by column chromatography on Diaion HP-20 (developed with water) to give 40 mg of disodium (6R,7R)-7[(Z)-2-(2-aminothiazol-4-yl)-2-(methoxyimino)acetoamido]-(2S)-2methyl-3-(2,5-dihydro-6-hydroxy-2-methyl-5-oxo-1,2,4 tr iaz in-3-yl) thiomethyl-l-oxa-l-dethia-3-cephem-4- carboxylate. IR (KBr), max(cm-Ú): 1765, 1660, 1600 NMR (D2O), (ppm): 1.44 (3H, d, J = 6.6 Hz), 3.63 (3H, s), 3.97 (3H, s), 3.96, 4.46 (2H, ABq, J = 13.9 Hz), 5.24 (1H, d, J = 3.4 Hz), 5.51 (1H, d, J = 3.4 Hz), 7.06 (1H, s) EXAMPLE 2 Production of disodium (6R,7R)-7[(Z)-2-(2 aminothiazol-4-yl)-2-(ethoxyimino)acetoamidol-(2S)- 2-methyl-3-(2,5-dihydro-6-hydroxy-2-methyl-5-oxo 1,2,4-triazin-3-yl)thiomethyl-1-oxa-1-dethia-3-cephem4-carboxylate (disodium salt of compound No. 2) of the formula: EMI32.1 wherein Et is an ethyl group. The reactions were carried out in a similar manner as in the steps (5)-(a), (b) and (c) of Example 1 using (Z)-2-(2-tritylaminothiazol-4-yl)-2ethoxyiminoacetic acid instead of the (Z)-2-(2-tri tylaminothiazol-4-yl) -2-methoxyimino-acetic acid as used in Example 1, the step (5)-(a), to give disodium salt of the titled compound. IR (KBr), max(cm ): 1765, 1660, 1600 NMR (D2O), (ppm): 1.20 (3H, t, J = 7.1 Hz), 1.36 (3H, d, J = 6.8 Hz), 3.54 (3H, s), 3.87, 4.40 (2H, ABq, J = 14.0 Hz), 4.15 (2H, q, J = 7.1 Hz), 5.16 (1H, d, J = 3.6 Hz), 5.44 (1H, d, J = 3.6 Hz), 6.96 (1H, s). EXAMPLE 3 (1) Production of diphenylmethyl 7ss-formamido-3- chloromethyl-l-oxa-l-dethia-3-cephem-4-carboxylate of the formula: EMI33.1 400 Mg of diphenylmethyl 7ss-formamido-1-oxa- l-dethia-3-methylenecepham-4-carboxylate was dissolved in 10 ml of methylene chloride. To the solution was added 458 mg of phenylselenyl chloride, and the mixture was agitated at ambient temperature for 1 hour and then admixed with 500 mg of 40% aqueous peracetic acid under ice-cooling, followed by agitation at ambient temperature for 30 minutes. The reaction solution was washed with saturated aqueous sodium bicarbonate, with aqueous sodium thiosulfate and then with water, dried over MgSO4 and concentrated. The residue was purified by column chromatography on silica gel developed with a development solvent of toluene-ethyl acetate (3:1), to give 330 mg (75%) of the titled compound. IR (CHC13), max(cm ): 1782, 1720, 1691 NMR (CDCl3), (ppm): 4.47 (4H, s), 5.05 (1H, d, J = 3.9 Hz), 5.73 (1H, dd, J = 9.6, 3.9 Hz), 6.43 (1H, d, J = 9.6 Hz), 6.88 (1H, s), 7.10-7.60 (10 H, m), 8.18 (1H, s) (2) Production of diphenylmethyl 7ss-amino-3- chloromethyl-l-oxa-l-dethia-3 -cephem-4 -carboxylate 330 Mg of diphenyl methyl 7ss-formamido-3- chloromethyl-l-oxa-l-dethia-3 -cephem-4 -carboxylate obtained in the step (1) just above was dissolved in 3 ml of methanol, to which 0.60 ml of 6N aqueous hydrogen chloride in dioxane was added, and the resulting mixture was agitated at ambient temperature for 30 minutes and concentrated. The residue was crystallized from methylene chloride to give 269 mg (89%) of the titled compound as hydrochloride. The free base of said compound shows the following physico-chemical properties: IR (CHCl3), max (cm 1): 1790, 1722 NMR (CDCl3), (ppm): 2.50 (2H, s), 4.30-4.75 (5H, m), 4.97 (1H, d), 6.90 (1H, s), 7.20-7.60 (10 H, m) (3) Production of disodium (6R,7R)-7-[(Z)-2-(2aminothiazol-4-yl)-2-(methoxyimino)acetoamido]-3-(2,5dihydro-6-hydroxy-2-methyl-5-oxo-1,2,4-triazin-3-yl) thiomethyl-l-oxa-l-dethia-3-cephem-4-carboxylate (disodium salt of compound No. 3) (a) 250 Mg of (Z)-2-(2-tritylaminothiazol-4-yl)2-methoxyimino-acetic acid and 200 mg of diphenylmethyl 7R-amino-3-chloromethyl-l-oxa-l-dethia-3 cephem-4-carboxylate hydrochloride were dissolved in 4 ml of methylene chloride, to which were further added 180 l of pyridine and 60 l of phosphorous oxychloride at -200C. The resulting mixture was agitated at the same temperature as above for 30 minutes and then under ice-cooling for 30 minutes. The reaction solution was washed twice (4 ml x 2) with ice-water, with saturated aqueous sodium bicarbonate and with water, dried over MgSO4 and concentrated. The residue was purified by column chromatography on silica gel developed with a development solvent of toluene-ethyl acetate (5:1) to yield 260 mg (69%) of diphenylmethyl 7ss-[(Z)-2-(2- tritylaminothiazol-4-yl)-2- (methoxyimino)acetoamidoi-3- chloromethyl-l-oxa-l-dethia-3-cephem-4-carboxylate of the formula: EMI35.1 IR (CHC13), max(cm ): 1800, 1725, 1685 NMR (CDC13), (ppm): 4.05 (3H, s), 4.54 (4H, s), 5.12 (1H, d, J = 3.8), 5.77 (1H, dd, J = 9.3, 3.8), 6.76 (1H, s), 6.91 (1H, s), 7.10-7.60 (25H, m) (b) 133 Mg of the product from the step (a) above, 34 mg of 2,5-dihydro-6-hydroxy-2-methyl-3 mercapto-5-oxo-1,2,4-triazine.sodium salt and 28 mg of sodium iodide were dissolved in DMF, and the solution was agitated at ambient temperature for 1 hour. The reaction solution was diluted with 6 ml of ethyl acetate, washed with acidified water (pH 3.0) and with water, dried and concentrated. The residue was purified by column chromatography on silica gel developed with a development solvent of chloroform-methanol (10:1) to give 120 mg (79%) of diphenylmethyl 7R-[(Z)-2-(2-tritylaminothiazol-4- yl)-2-(methoxyimino)acetoamido]-3-(2,5-dihydro-6- hydroxy-2-methyl-5-oxo-1,2,4-triazin-3-yl)thiomethyll-oxa-l-dethia-3-cephem-4-carboxylate. (c) 120 Mg of the product from the step (b) above was added to a mixture of trifluoroacetic acid 1.5 ml) and anisol (0.2 ml) under ice-cooling. After agitation of the resulting solution at the same temperature as above for 30 minutes, 6 ml of isopropylether (IPE) was added to the solution to deposit a precipitate which was removed by filtration. The precipitate (72 mg) obtained and sodium bicarbonate (30 mg) were dissolved in 2 ml of water, and purified by column chromatography on Diaion HP-2 developed with water to afford the titled compound as disodium (6R,7R)-7-[(Z)-2-(2-aminothiazol-4-yl)-2 (methoxyimino)acetoamido] -3- (2,5-dihydro-6-hydroxy-2- methyl-5-oxo-1,2,4-triazin-3-yl)thiomethyl-1-oxa-1- dethia-3-cephem-4-carboxylate. IR (KBr), max(cm ): 1765, 1660, 1600 NMR (D2O), (ppm): 3.60 (3H, s), 3.95 (3H, s), 4.04, 4.33 (2H, d, J = 14 Hz) 4. 4 (2H, s), 5.25 (1H, d, J = 3.6 Hz), 5.56 (1H, d, J 3.6 Hz), 6.96 (1H, s) EXAMPLE 4 Production of disodium (6R,7R)-7-[(Z-)-2-(2 aminothiazol-4-yl)-2-(ethoxyimino)acetoamidol-3-(2,5- dihydro-6-hydroxy-2-methyl-5-oxo-1,2,4-triazin-3-yl) thiomethyl-l-oxa-l-dethia-3-cephem-4-carboxylate (disodium salt of compound No. 4) The reaction was carried out in a similar manner as in Example 3, step (3)-(a) using (Z)-2-(2- tritylaminothiazol-4-yl)-2-ethoxyimino-acetic acid instead of the (Z)-2-(2-tritylaminothiazol-4-yl)-2methoxyimino-acetic acid, to give disodium salt of the titled compound. IR (KBr) max(cm ): 1765, 1670, 1600 NMR (D2O), (ppm): 1.33 (3H, t, J = 7.0 Hz), 3.69 (3H, s), 4.14, 4.40 (2H, ABq, J = 12.0 Hz), 4.30 (2H, q, J = 7.0 Hz), 4.63 (2H, s), 5.34 (1H, d, J = 3.7 Hz), 5.64 (1H, d, J = 3.7 Hz), 7.05 (1H, s) EXAMPLE 5 Production of disodium (6R,7R)-7-[2-(2 aminothiazol-4-yl)-2-(4-ethyl-2,3-dioxo-1-piperzine- carboxamido)acetoamidol-(2S)-2-methyl-3-(2,5-dihydro- 6-hydroxy-2-methyl-5-oxo-1,2,4-triazin-3-yl)thiomethyl-l-oxa-l-dethia-3-cephem-4-carboxylate (disodium salt of compound No. 5) (1) 227 Mg of diphenylmethyl 7ss-amino-2ss-methyl- 3-chloromethyl-l-oxadethia-3-cephem-4-carboxylate and 341 mg of potassium DL-2-(4-ethyl-2,3-dioxo-lpiperazinecarboxamido)-2-(tritylaminothiazol-4-yl) acetate were dissolved in 6 ml of methylene chloride. To the solution were added 160 l of pyridine and 65 iil of phosphorous oxychloride at -200C, and the mixture was agitated at the same temperature as above for 30 minutes and further under ice-cooling for 30 minutes. The reaction solution was washed with acidified water (pH 3.0), with saturated aqueous sodium bicarbonate and then with water, dried over MgSO4 and concentrated. The diastereomers so obtained, which were composed of two isomers having Rf value 0.43 and 0.26, respectively (silica gel chromatography; developed with ethyl acetate), were separated from each other and purified by column chromatography on silica gel developed with a development solvent of toluene-ethyl acetate (1:2). There were thus obtained 172 mg of the isomer (corresponding to Rf = 0.43) and 149 mg of the isomer (corresponding to Rf 0.26) of diphenylmethyl 7ss-[2-(4-ethyl-2,3-dioxo-1-piperazinecarboxamido)-2-(2- tritylaminothiazol-4-yl)acetoamido]-2ss-methyl-3-chloro- methyl-l-oxa-l-dethia-3-cephem-4-carboxylate of the formula EMI38.1 The compound of Rf 0.43 shows: NMR(CDC13), (ppm): 1.22 (3H, t, J = 7.3 Hz), 1.26 (3H, d, J = 5.9 Hz), 3.47-4.20 (4H, m), 4.04, 5.11 (2H, ABq, J = 12.4 Hz), 4.11 (2H, q, J = 7.3 Hz), 4.65 (1H, q, J = 5.9 Hz), 5.07 (lH, d, J = 4.0 Hz), 5.55 (1H, d, J = 7.3 Hz), 5.71 (1H, dd, J = 3.7, 9.5 Hz), 6.26 (1H, s), 6.58 (1H, s), 6.88 (1H, s), 7.20-7.60 (25H, m), 7.85 (1H, d, J = 9.5 Hz), 9.75 (1H, d, J = 7.4 Hz) The compound of Rf 0.26 shows: NMR(CDC13), (ppm): 1.21 (3H, t, J = 7.1 Hz), 1.39 (3H, d, J = 6.6 Hz) 3.50-4.18 (4H, m) 4.04, 5.16 (2H, ABq, J = 12.4 Hz), 4.11 (2H, q, J = 7.1 Hz), 4.73 (1H, q, J = 6.6 Hz), 4.75 (1H, d, J = 4.0 Hz), 5.50 (1H, d, J = 6.9 Hz), 5.64 (1H, dd, J = 4.0, 9.1 Hz), 6.29 (1H, s), 6.58 (1H, s), 6.87 (1H, s), 7.20-7.50 (25H, m), 7.57 (1H, d, J = 9.1 Hz), 9.77 (lH, d, J = 6.9 Hz) (2) Following steps are described for the isomer compound of Rf 0.43, but are equally applicable to the isomer compound of Rf 0.26. 113 Mg of the isomer compound (Rf = 0.43) mentioned above, 23 mg of 2,5-dihydro-6-hydroxy2-methyl-3-mercapto-5-oxo-1,2,4-triazine sodium salt and 17 mg of NaI were dissolved in 0.5 ml of DMF. The solution obtained was agitated at ambient temperature for 2 hours. The reaction solution was diluted with ethyl acetate and washed with acidified water (pH 3.0) and then with water, dried over MgSO4 and concentrated. The residue was purified by column chromatography on silica gel developed with a development solvent of chloroform-methanol (20:1) to give 115 mg of diphenylmethyl 7ss-[2-(4-ethyl-2,3- dioxo-l-piperazinecarboxamido) -2- (2-tritylaminothiazol- 4-yl)acetoamido]-2ss-methyl-3-(2,5-dihydro-6-hydroxy-2- methyl-5-oxo-1,2,4-triazin-3-yl)thiomethyl-1-oxa-1- dethia-3-cephem-4-carboxylate. (3) 115 Mg of the product from the step (2) above was added to a mixture of trifluoroacetic acid (1.2 ml) and anisol (0.2 ml) under ice-cooling, and the resulting mixture was agitated at the same temperature as above for 30 minutes. To the reaction mixture was added IPE to deposit a precipitate which was then removed by filtration. The precipitate obtained by filtration and sodium bicarbonate (35 mg) were dissolved in 1 ml of water and purified by column chromatography on silica gel developed with water to give disodium salt of the title compound which shows the following physicochemical properties: -l IR (KBr), (cm ): 1765, 1710, 1675, 1610 NMR(D2O), (ppm): 1.18 (3H, t, J = 7.4 Hz),1.35 (3H, d, J = 6.6 Hz), 3.30-4.10 (4H, m), 3.50 (2H, q, J = 7.4 Hz), 3.61 (3H, s), 3.94, 4.43 (2H, ABq, J = 13.3 Hz), 5.12 (1H, d, J = 4.6 Hz), 5.42 (1H, s), 5.43 (1H, d, J = 4.6 Hz), 6.76 (1H, s), On the other hand, disodium (6R, 7R)-7 [2-(2-aminothiazol-4-yl)-2-(4-ethyl-2,3-dioxo-1piperazine-carboxamido)acetoamido]-(2S)-2-methyl-3 (2,5-dihydro-6-hydroxy-2-methyl-5-oxo-l,2,4-triazin-3- yl)thiomethyl-l-oxa-l-dethia-3-cephem-4-carboxylate (disodium salt of compound No. 5) was obtained in the same manner as mentioned above for the compound Rf 0.43 from the isomer compound of Rf 0.26, and it shows the following physicochemical properties: IR(KBr), max (cm-Ú): 1763, 1710, 1678, 1610 NMR(D2O), (ppm): 1.18 (3H, t, J = 7.3 Hz), 1.42 (3H, d, J = 6.6 Hz), 3.30-4.10 (4H, m), 3.50 (2H, q, J = 7.3 Hz), 3.62 (3H, s), 3.94, 4.44 (2H, ABq, J = 13.9 Hz), 5.17 (1H, d, J = 3.6 Hz), 5.37 (1H, d, J = 3.6 Hz), 5.43 (1H, s), 6.74 (1H, s) EXAMPLE 6 Production of disodium (6R, 7R)-7-[2-(2 aminothiazol-4-yl)-2-(formamido)acetoamido]-(2S3-2- methyl-3-(2,5-dihydro-6-hydroxy-2-methyl-5-oxo-1,2,4triazin-3-yl)thiomethyl-1-oxa-1-dethia-3-cephem-4carboxylate-(disodium salt of compound No. 6) (1) 130 Mg of diphenylmethyl 7ss-amino-2ss-methyl-3- chloromethyl-l-oxadethia-3-cephem-4-carboxylate hydrochloride and 136 mg of sodium DL-2-(2-tritylaminothiazol-4yl)-2-formamido-acetate were dissolved in 10 ml of methylene chloride. To the solution obtained were added 105 l of pyridine and 35 iji of phosphorous oxychloride at -200C, and the mixture was agitated at the same temperature as above for 30 minutes and then under ice-cooling for 30 minutes. The reaction solution was washed with acidified water (pH 3.0), with saturated aqueous sodium bicarbonate and then with water, dried over MgSO4 and concentrated. The residue was purified by column chromatography on silica gel developed with a development solvent of toluene-ethyl acetate (1:1) to give 160 mg of diphenylmethyl 7R-[DL-2-(2-tritylaminothiazol-4- yl)-2-(formamido)acetoamido]-2,3-methyl-3-chloromethyl-l-oxa-l-dethia-3-cephem-4-carboxylate. IR (CHCl3), max(cm-Ú): 1776, 1725, 1660 NMR(CDC13), (ppm): 1.27, 1.38 (3H, d), 4.05, 5.13 (2H, ABq, 4.66, 4.73 (1H, q), 4.95, 5.07 (1H, d), 5.50, 5.55 (1H, d), 5.64, 5.71 (1H, dd), 6.29 (1H, s), 6.58 (1H, s), 6.88 (1H, s), 7.20-7.60 (25H, m) , 8.34 (1H, s) , 9.77 (1H, d) (2) 160 Mg of the product from the step (1) above, 41 mg of 2,5-dihydro-6-hydroxy-2-methyl-3-mercapto5-oxo-1,2,4-triazine sodium salt and 34 mg of sodium iodide were dissolved in 1 ml of DMF, and the solution was agitated at ambient temperature of 1 hour. The reaction solution was diluted with 10 ml of ethyl acetate and washed with acidified water (pH 3.0 and then with water, dried over MgSO4 and concentrated. The residue was purified by column chromatography on silica gel developed with chloroformmethanol (10:1) to give 150 mg of diphenylmethyl 7ss-[DL-2-12-tritylamino-thiazol-4-yl)-2-(formamido) acetoamido]-2ss-methyl-3-(2,5-dihydro-6-hydroxy-2- methyl-5-oxo-1,2,4-triazin-3-yl)thiomethyl-1-oxadethia- 3-cephem- 4 -carboxylate. (3) 150 Mg of the product from the step (2) above was added to a mixture of trifluoroacetic acid (2 ml) and anisol (0.2 ml) under ice-cooling, and the mixture obtained was agitated at the same temperature as above for 30 minutes, to which then 10 ml of IPE was added to deposit a precipitate which was removed by filtration. The precipitate (100 mg) obtained and sodium bicarbonate (50 mg) were dissolved in 1 ml of water and purified by column chromatography on Diaion HP-20 developed with water to give 55 mg of disodium salt of the titled compound (Compound No. 6). NMR(D2O), (ppm): 1.39, 1.45 (3H, d), 3.61 (3H, s), 3.81, 4.42 (2H, ABq), 5.12, 5.16 (1H, d), 5.37, 5.43 (1H, d), 5.42, 5.43 (1H, s), 6.76 (1H, s), 8.18 (1H, s) EXAMPLE 7 Production of disodium (6R, 7R)-7-[2-(2 aminothiazol-4-yl)-2-(4-ethyl-2,3-dioxo-1-piperazine- carboxamido)acetoamido] -3-(2,5-dihydro-6-hydroxy-2- methyl-5-oxo-1,2,4-triazin-3-yl)thiomethyl-1-oxa-1- dethia-3-cephem-4-carboxylate (disodium salt of compound No. 7). (1) 350 Mg of diphenylmethyl 7ss-amino-3-chloromethyl- l-oxadethia-3-cephem-4-carboxylate hydrochloride and 560 mg of potassium DL-2-(4-ethyl-2,3-dioxo-lpiperazinecarboxamido)-2-(2-triethylaminothiazol-4-yl) acetate were dissolved in 20 ml of methylene chloride. To the solution obtained were added pyridine (260 ) and phosphorous oxychloride (85 at -200C, and the resulting mixture was agitated at the same temperature as above for 30 minutes and under ice-cooling for 30 minutes. The reaction solution was washed with acidified water (pH 3.0), saturated aqueous sodium bicarbonate and water, dried over MgSO4 and concentrated. The diasteromers obtained, which were composed of two isomers having Rf value 0.46 and 0.24, respectively (silica gel chromatography; developed with ethyl acetate), were separated from each other and purified by column chromatography on silica gel developed with a development solvent of toluene-ethyl acetate (1:1). There were thus obtained 180 mg of the isomer compound (Rf=0.46) and 200 mg of the other isomer compound (Rf=0.24) of diphenyl methyl 7R-[2-(4-ethyl-2,3-dioxo-l- piperazinecarboxamido)-2-(2-tritylaminothiazol-yl) acetamido]-3-chloromethyl-1-oxadethia-3-cephem-4carboxylate. The compound of Rf 0.46 shows: NMR(CDC ), (ppm): 3.40-4.30 (4H, m), 4.35, 4.23 (2H, ABq, J = 18 Hz), 4.48, 4.37 (2H, ABq, J = 15 Hz), 5.04 (1H, d, J = 40 Hz), 5.59 (1H, d, J = 10 Hz), 5.75 (1H, dd, J = 4.10 Hz), 6.23 (1H, s), 6.68 (1H, s), 6.90 (1H, s), 7.10-7.60 (25H, m) The compound of Rf 0.24 shows: NMR(CDC13), (ppm): 3.40-4.30 (4H, m), 4.47 (2H, s), 4.59, 4.40 (2H, ABq, J = 12 Hz), 5.66 (1H, d, J = 4 Hz), 5.52 (1H, d, J = 9 Hz), 5.67 (1H, dd, J = 4, 9 Hz), 6.28 (1H, s,), 6.68 (lH, s), 6.89 (1H, s), 7.10-7.60 (25H, m) (2) The following steps were conducted in respect of the isomer compound (Rf = 0.46), as well as the isomer compound (Rf = 0.24). 125 Mg of the above compound (Rf = 0.46), 25 mg of 2,5-dihydro-6-hydroxy-2-methyl-3-mercapto-5oxo-1,2,4-triazine sodium salt and 21 mg of NaI were dissolved in 1 ml of DMF, and the resulting solution was agitated at ambient temperature for 1 hour. The reaction solution was diluted with 6 ml of ethyl acetate, washed with acidified water (pH 3.0) and then with water, dried over MgSO4 and concentrated. The residue was purified by column chromatography on silica gel developed with a development solvent of chloroform-methanol (10:1) to give 120 mg of diphenylmethyl 7ss-[2-(4-ethyl-2,3- dioxo-l-piperazinecarboxamido) -2- (2-tritylaminothiazol- 4-yl)acetoamido]-3-(2,5-dihydro-6-hydroxy-2-methyl- 5-oXo-1,2,4-triazin-3yl)thiomethyl-1-oxa-1-dethia-3- cephem-4-carboxylate. (3) 120 mg of the product from the step (2) above was added to a mixture of trifluoroacetic acid (1.2 ml) and anisol (0.2 ml) under ice-cooling, and the mixture so obtained was agitated at the same temperature as above for 30 minutes, to which was added IPE to give a precipitate which was removed by filtration. The precipitate so obtained and 32 mg of sodium bicarbonate were dissolved in 2 ml of water and purified by column chromatography on Diaion Hp-20, affording 50 mg of disodium salt of the titled compound (compound No. 7). IR (KBr), max(cm 1762, 1710, 1673, 1600 NMR(D2O), (ppm): 1.18 (3H, t, J = 7.4 Hz), 3.50 (2H, q, J = 7.4 Hz), 3.40 4.10 (4H, m), 3.59 (3H, s), 4.04, 4.28 (2H, ABq, J = 14.5 Hz), 4.43 (2H, s), 5.12 (1H, d, J = 4.0 Hz), 5.43 (1H, d, J = 4.0 Hz), 5.45 (1H, s), 6.68 (1H, s) Disodium salt of the title compound (disodium salt of compound No. 7) obtained from the compound (Rf = 0.24) shows the following physicochemical properties: IR (KBr), max(cm 1765, 1710, 1677, 1610 NMR(D2O), (ppm): 1:18 (3H, t, J = 7.4 Hz), 3.48 (2H, q, J = 7.4 Hz), 3.40-4.10 (4H, m), 3.59 (3H, s), 4.07, 4.29 (2H, ABq, J = 14.3 Hz), 4.47 (2H, s), 5.18 (1H, d, J = 4.0 Hz) , 5.43 (1H, d, J = 4.0 Hz), 5.45 (1H, s), 6.68 (1H, s) EXAMPLE 8 Production of disodium (6R, 7R)-7-[2-(2aminothiazol-4-yl)-2-(formamidio)acetoamido]-3-(2, 5-dihydro-6-hydroxy-2-methyl-5-oxo-1,2,4-triazin 3-yl) thiomethyl-l-oxa-1-dethia-3-cephem-4-carboxylate (disodium salt of compound No. 8). (1) 174 Mg of diphenylmethyl 7ss-amino-3- chloromethyl-1-oxadethia-3-cephem-4-carboxylate hydrochloride and 279 mg of sodium DL-2-(2tritylaminothiazol-4-yl)-2-formamidoacetate were dissolved in 10 ml of methylene chloride. To the solution were added 130 of pyridine and 47 of phosphorous oxychloride at -200C, and the resultant solution was agitated at the same temperature as above for 30 minutes and then under ice-cooling for 30 minutes. The reaction solution was washed with acidified water (pH 3.0), with saturated aqueous sodium bicarbonate and then with eater, dried over MgSO4 and concentrated. The residue was purified by column chromatography on silica gel developed with a solvent system of toluene-ethyl acetate (1:1), to give 235 mg of diphenylmethyl 7R-[DL-2-(2-tritylaminothiazol-4- yl)-2-(formamidoacetoamido]-3-chloromethyl-1-oxa-1- dethia-3-cephem-4-carboxylate. NMR(CDC13), (ppm): 4.30, 4.61, 4.32, 4.60 (2H, ABq) , 4.30, 4.43 (2H, s), 5.00, 5.05 (1H, d), 5.50, 5.52 (1H, d), 5.55, 5.66 (1H, dd), 6.20, 6.22 (1H, s), 6.60, 6.64 (1H, s), 6.89, 6.96 (1H, s), 7.10 7.70 (25H, m), 8.20, 8.24 (1H, s) (2) 190 Mg of the product from the step (1) above, 50 mg of 2,5-dihydro-6-hydroxy-2-methyl-3mercapto-5-oxo-1,2,4-triazine sodium salt, 42 mg of NaI were dissolved in 1 ml of DMF, and the solution was agitated at ambient temperature for 1 hour. The reaction solution was diluted with 7 ml of ethyl acetate, washed with acidified water (pH 3.0) and then with water, dried over MgSO4 and concentrated. The residue was purified by column chromatography on silica gel developed with a solvent system of chloroform-methanol (10:1), to give 176 mg of diphenylmethyl 7R-[DL-2-(2-tritylaminothiazol-4- yl)-2-(formamido)acetoamido]-3-(2,5-dihydro-6-hydroxy 2-methyl-5-oxo-1,2,4-triazin-3-yl)thiomethyl-1-oxa-1- dethia-3 -cephem-4 -carboxylate. (3) 176 mg of the product from the step (2) above was added to a mixture of trifluoroacetic acid (2 ml) and anisol (0.2 ml) under ice cooling. The mixture so obtained was agitated at the same temperature as above for 30 minutes. To the reaction solution was then added 10 ml of IPE to deposit a precipitate which was removed by filtration. The precipitate obtained (105 mg) and sodium bicarbonate (54 mg) were dissolved in 1 ml of water, purified by column chromatography on Diaion HP-20 developed with water, to give 62 mg of disodium salt of the titled compound (compound No. 8). NMR(D2O), (ppm): 3.60 (3H, s), 3.96, 4.25 (2H, ABq) 4.43, 4.48 (2H, s), 5.10 (1H, d), 5.45 (1H, s), 5.38, 5.56 (7H, d), 6.64 (1H, s), 8.13 (1H, s).

Claims: WHAT IS CLAIMED IS: 1. A l-oxa-l-dethia-cephalosporin compound represented by the general formula (I) EMI49.1 wherein R1 is a group of the formula: EMI49.2 where R4 is loweralkyl (1-6 carbons) including a methyl group or an ethyl group, or R1 is a group of the formula: EMI49.3 where R5is a hydrogen atom, a 4-ethyl-2,3-dioxopiperazin-l-yl group or a 5- or 6-membered heterocyclic radical having 2 ring nitrogens as the sole hetero substituent in the ring and having at least one hetero group on the carbon adjacent to the ring nitrogens of the formula: EMI50.1 and the carbon atom to which the asterisk is attached shows (R)-configuration or (S)-configuration or a mixture of these configurations; both of R2 and R3 are each a hydrogen atom or either one of R2 and R3 is a hydrogen atom and the other a methyl group, and a pharmaceutically acceptable hydrate, salt or ester thereof. 2. An antibacterial agent comprising as active ingredient a therapeutically effective amount of at least one of a l-oxa-l-dethia-cephalosporin compound of the general formula (I) EMI51.1 wherein R1 is a group of the formula: EMI51.2 where R4 is a methyl group or an ethyl group, or R1 is a group of the formula: EMI51.3 where R5 is a hydrogen atom, a 4-ethyl-2,3-dioxopiperazin-l-yl group, or a 5- or 6-membered heterocyclic radical having 2 ring nitrogens as the sole hetero substituent in the ring and having at least one hetero group on the carbon adjacent to the ring nitrogens of the formula: EMI52.1 and the carbon atom to which the asterisk is attached shows (R)-configuration or (S)-configuration or a mixture of these configurations; both of R2 and R3 are each a hydrogen atom, or either one of R2 and R3 is a hydrogen atom and the other a methyl group, a pharmaceutically acceptable hydrate, salt or ester thereof and a pharmaceutically acceptable carrier. 3. A l-oxo-l-dethia-cephalosporin compound represented by the general formula (IIb) EMI52.2 in which either Ra is a hydrogen atom and Rb is a methyl group, or Ra is a methyl group and Rb is a hydrogen atom X is a chlorine atom, a bromine atom or an iodine atom, and R7 is a hydrogen atom or a carboxyl-protecting group.

Inventors: CHRISTENSEN, BURTON G., FUKATSU, SHUNZO, MURAI, YASUSHI, NIIDA, TARO, OKONOGI, TSUNEO, SHIBAHARA, SEIJI, WAKAZAWA, TADASHI
Applicants: MEIJI SEIKA KAISHA LTD., MERCK & CO. INC.
Application year: 1985
Main classification: C07D498
IPC codes: C07D505, A61P31, A61K31, C07D498, C07D493