DERIVATI DELLA CEFALOSPORINA LORO PREPARAZIONE E LORO IMPIEGO COME ANTIBIOTICI

Novel compounds of formula I, in which R1 is hydrogen, alkyl, phenylalkyl, carbalkoxyalkyl, acyl, carboxyalkyl, alkoxyalkyl, hydroxyalkyl, cyanoalkyl, or carbamoylalkyl, R2 is hydrogen, pivaloyloxymethyl or the residue of an easily splittable ester grouping, R3 is a pyrazolyl radical, unsubstituted or mono- or di-substituted by alkyl, phenyl, alkoxy, alkylthio, carboxy, carboxyalkyl, carbamoyl, carbamoylalkyl, alkylsulphonyl, azido, acylamino, hydrazino, acylhydrazino alkylidenehydrazino, phenylidenehydrazino, in which the phenyl nucleus is unsubstituted or substituted by NH2, lower alkoxy or lower alkyl, furylidenehydrazino, carbalkoxy or a group R5R6N-, in which R5 and R6 are the same or different and are hydrogen or alkyl, provided that the nitrogen atoms and the 4-position of the pyrazole nucleus are either unsubstituted or substituted by alkyl, phenyl, or carbalkoxy, and R4 is hydrogen, acetoxy, carbamoyloxy or -S-Rh, in which Rh is a heterocyclic radical.