| 摘要 |
There is provided compounds of the formula: 1 wherein R stands for benzyl, phenoxymethyl, 4-amino-4-carboxy-1-butyl, .alpha.-aminobenzyl and protected derivatives thereof, lower alkyl, aryl and heteroaryl, R3O-, R3S-, R3R4N- wherein R3 is lower alkyl, phenyl, or phenylloweralkyl, R4 is hydrogen or R3; R1 is hydrogen or a cleavable radical lower alkyl, 2,2,2-trichloroethyl, benzyl, p-nitrobenzyl, benzhydryl, phenacyl, or trimethylsilyl, and R2 is hydrogen or methoxy. These compounds possess antibiotic activity and are also useful in preparing known penicillins and cephalosporins. |
