PENCILLINS AND CEPHALOSPORINS

摘要

Pencillins and cephalosporins of formula I, …… in which R1 is hydrogen or pivaloyloxymethyl,… R2 is phenyl, 4-hydroxyphenyl or 1,4-cyclohexadien-1-yl,… R3 is hydrogen, lower alkyl or lower alkylthio,… R4 and R5, which may be the same or different, are hydrogen, lower alkyl, hydroxy, lower alkoxy,… carboxyl, lower alkoxycarbonyl, lower alkoxycarbonylmethyl, carboxymethyl or halogen,… A is the group …… in which R6 is hydrogen or lower alkyl,… B is oxygen of sulphur,… X is a group of formula IIa or IIb, …… in which R7 is hydrogen, acetoxy or a group of formula IIc, …… and Ring D is a 5- or 6-membered, unsaturated ring,… which may contain one or more hereto atoms, and salts of compounds of formula I, in which R1 is hydrogen, methods for their production and their anti-bacterial use.