Process for preparing 7-methoxycephalosporin compounds

Claim 1

A process for preparing a 7α-methoxy-3-cephem-4-carboxylic acid having the formula ##STR40## wherein R represents cyanomethylthio, 1-cyanoethylthio, azidomethylthio, propargylthio, 2-hydroxyethylthio, 2,3-dihydroxypropylthio, methylsulfonyl, ethylsulfonyl, cyanoethylsulfonyl, 3-isoxazolyloxy, 3-isoxazolylthio, 2-(1,3,4-thiadiazolyl)thio, 2-imidazolythio or sydnon-3-yl nd R 1 is acetoxy, carbamoyloxy or 1-methyl-1H-tetrazol-5-ylthio or a salt with the carboxyl group thereof which comprises the steps of contacting a 7β-benzylidenemino-7α-methoxy-3-cephem-4-carboxylic acid having the formula ##STR41## wherein R 1 is the same as defined above, R 2 , R 3 , R 4 and R 5 may be the same or different and each represents hydrogen atom, an alkyl having 1-4 carbon atoms, an alkoxy having 1-4 carbon atoms, or a halogen atom, or R 2 and R 3 or R 4 and R 5 may be linked together to form a saturated, unsaturated or aromatic ring, n is an integer of 1 or 2 and Y + is a cation selected from the group consisting of an alkali metal ion and an ammonium ion having the formula ##STR42## wherein R a , R b , R c and R d can be the same or different, and each is selected from the group consisting of hydrogen alkyl having from 1 to 8 carbon atoms, cyclopentyl, cyclohexyl, cycloheptyl, phenyl, phenylalkyl wherein the alkyl has from 1 to 4 carbon atoms, R a and R b can be linked together with said N to form a saturated heterocyclic ring, and R a , R b and R c can be linked together with said N to form a heterocyclic ring, with a hyrazine to give a 7-amino-7-methoxy-3-cephem-4-carboxylic acid having the formula ##STR43## wherein R 1 and Y + are the same as defined above, and reacting the latter compound with a compound selected from the group consisting of a carboxylic acid having the formula RCH.sub.2 COOH (IV) wherein R is the same as defined above, an acid halide of (IV), an azide of (IV), an acid anhydride of (IV), a p-nitrophenyl ester of (IV), cyanomethyl ester of (IV) and a phthalimide ester of (IV).