| abstract |
Pencillins and cephalosporins of formula I, n<CHEM>n in which R1 is hydrogen or pivaloyloxymethyl,n R2 is phenyl, 4-hydroxyphenyl or 1,4-cyclohexadien-1-yl,n R3 is hydrogen, lower alkyl or lower alkylthio,n R4 and R5, which may be the same or different, are hydrogen, lower alkyl, hydroxy, lower alkoxy,n carboxyl, lower alkoxycarbonyl, lower alkoxycarbonylmethyl, carboxymethyl or halogen,n A is the group n<CHEM>n in which R6 is hydrogen or lower alkyl,n B is oxygen of sulphur,n X is a group of formula IIa or IIb, n<CHEM>n in which R7 is hydrogen, acetoxy or a group of formula IIc, n<CHEM>n and Ring D is a 5- or 6-membered, unsaturated ring,n 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. |