Method for cyclization to give cephem ring

A process for preparing a compound of the formula ##STR27## wherein A is amino, sulfenylamino or amino substituted by (1) C.sub.1 to C.sub.10 alkanoyl, (2) C.sub.1 to C.sub.5 haloalkanoyl, (3) azidoacetyl, (4) cyanoacetyl, (5) acyl of the formula Ar--CQQ'--CO-- in which each of Q and Q' is hydrogen or methyl and Ar is phenyl, dihydrophenyl or a monocyclic hetero aromatic group containing 1-4 hetero ring atoms selected from the group consisting of nitrogen, oxygen and sulfur, (6) 2-sydnon-3-acetyl, (7) (4-pyridon-1-yl)acetyl, (8) acyl of the formula Ar--G--CQQ'--CO-- in which Ar, Q and Q' are as defined above and G is oxygen or sulfur, (9) acyl of the formula ##STR28## in which Ar is as defined above and T is hydroxy, C.sub.1 to C.sub.10 acyloxy, carboxy, C.sub.2 to C.sub.7 alkoxycarbonyl, C.sub.2 to C.sub.15 aralkoxycarbonyl, C.sub.1 to C.sub.12 aryloxycarbonyl, C.sub.1 to C.sub.7 alkanoyloxy-C.sub.1 to C.sub.3 alkoxycarbonyl, cyano, carbamoyl, sulfo or C.sub.1 to C.sub.7 alkoxysulfonyl, (10) acyl of the formula ##STR29## in which Ar is as defined above and each of W and W' is hydrogen, C.sub.2 to C.sub.7 alkoxycarbonyl, C.sub.3 to C.sub.10 cycloalkyl-C.sub.2 to C.sub.3 alkoxycarbonyl, C.sub.5 to C.sub.8 cycloalkoxycarbonyl, C.sub.1 to C.sub.4 alkylsulfonyl-C.sub.1 to C.sub.4 alkoxycarbonyl, halo C.sub.1 to C.sub.3 alkoxycarbonyl, C.sub.1 to C.sub.15 aralkoxycarbonyl, C.sub.1 to C.sub.10 alkanoyl, C.sub.2 to C.sub.15 aroyl, pyronecarbonyl, thiopyronecarbonyl, pyridonecarbonyl, carbamoyl, guanidinocarbonyl, 3-methyl-2-oxoimidazolidin-1-ylcarbonyl, 3-methanesulfonyl-2-oxoimidazolidin-1-ylcarbonyl, 4-methyl-2,3-dioxopiperazin-1-ylcarbonyl, or 4-ethyl-2,3-dioxopiperazin-1-ylcarbonyl, or W and W' are combined together with the nitrogen atom to which they are attached to form phthalimido, maleimido or enamino derived from C.sub.5 to C.sub.10 acetoacetate, C.sub.4 to C.sub.10 acetacetamide, acetylacetone, acetoacetonitrile or 1,3-cyclopentanedione, (11) acyl of the formula ##STR30## in which Ar is as defined above and E is hydrogen or C.sub.1 to C.sub.5 alkyl, (12) 5-aminoadipoyl, N-protected 5-aminoadipoyl wherein the protecting group is C.sub.1 to C.sub.10 alkanoyl, C.sub.1 to C.sub.10 aralkanoyl, C.sub.2 to C.sub.11 aroyl, C.sub.1 to C.sub.5 haloalkanoyl or C.sub.2 to C.sub.10 alkoxycarbonyl, or carboxy-protected 5-aminoadipoyl wherein the protecting group is C.sub.1 to C.sub.5 alkyl, C.sub.2 to C.sub.21 aralkyl or C.sub.1 to C.sub.10 aryl, (13) acyl of the formula L-O-CO- in which L is C.sub.1 to C.sub.10 hydrocarbyl, (14) diacylimido derived from a C.sub.4 to C.sub.10 polybasic carboxylic acid, (15) C.sub.1 to C.sub.20 hydrocarbyl, (16) C.sub.1 to C.sub.20 hydrocarbylidene, (17) C.sub.2 to C.sub.10 organic silyl, (18) azido, (19) isocyanato, or (20) isocyano,

• Cob is a carboxylic ester group,
• Rs is benzothiazol-2-ylthio, thiazol-2-ylthio or acetylthio,
• Y is C.sub.1 to C.sub.5 alkanoyloxy, C.sub.1 to C.sub.5 alkoxycarbonyloxy, C.sub.7 to C.sub.12 aralkoxycarbonyloxy, C.sub.6 to C.sub.11 aroyloxy, C.sub.1 to C.sub.5 alkanesulfonyloxy, C.sub.6 to C.sub.8 arylsulfonyloxy, cyano, thiocyanato, nitro, nitroso, chlorine, bromine or iodine, and
• the dotted line represents a 2- or 3- double bond,
• which comprises reacting a compound of the formula ##STR31## wherein A, COB, RS and Y have the same meanings as above, with a base selected from the group consisting of trimethylamine, triethylamine, tripropylamine, butyldimethylamine, 1-methylpiperdine, N-methylmorpholine, quinuclidine, 4-piperidylpyridine, 1,2,2,6,6-pentamethylpiperidine, 1,4-diazabicyclo[2,2,2]octane, N,N-dimethylaniline, 1,8-bisdimethylaminonaphthalene and diisopropylamine.