7,3-Substd-3-cephem-4-carboxylic acids - prepd directly from cephalosporin C culture broths

摘要

Cpds. of formula (I): (where R is R1X or COOR4; X is CO or SO2; R1 is an org. gp.; R4 is aralkyl; Y is the residue of a strong nucleophile, preF. N3 or 5-methy-1,3,4-thiadiazol-2-ylthio), are inters. for the corresp. 3-(YCH2)-7-amino-3-cephem-4-carboxylic acids, into which they can be converted by silylating, converting into an imino-halide, converting into an imino-ester, and hydrolysing. Cpds. (I) are pref. by treating a fermentation broth contg. cephalosporin C with an acylating agent and reacting the prodt. with YH, or by treating the broth with YH and reacting the prodt. with the acylating agent.