| 摘要 |
"PROCESS FOR PREPARING CEPHALOSPORIN DERIVATIVES" Cephalosporin derivatives of formula (I): (I) (wherein: R2 represents a lower alkoxymethyl group, a lower alkoxycarbonylalkoxymethyl group, an aralkyloxymethyl group or a hydrogen atom; R3 represents a substituted or unsubstituted 1H-tetrazol-5-yl group, 1,3,4-thiadiazol-2-yl group or 1H-1,2,3-triazol-5-yl group, and R5 represents an acyl group) and pharmaceutically acceptable salts thereof are prepared by reacting a compound of formula (II): (II) (wherein: R1 represents a acylamido group, an alkoxycarbonylamido group, an aralkyloxycarbonylamido group or a phthaloylamino group; R2a represents a lower alkoxymethyl group, a lower alkoxycarbonylalkoxymethyl group or an aralkyloxymethyl group; and R3 is as defined above) with a compound of formula (III): R5 - X (III) (wherein R5 is as defined above and X represents a halogen atom), optionally acidifying the resulting ester to convert it to the free acid and then optionally salifying the acid. In accordance with the invention, the transacylation reaction is effected in the presence of a compound of formula (IV): (IV) (wherein R4 represents a lower alkyl group, an aryl group or an aryloxyalkyl group) and in a halogenated hydrocarbon solvent containing at least one mole of water per mole of said compound of formula (II). |
