| abstract |
There are provided compounds of the formula Ia and Ib <CHEM> wherein A is hydrogen atom or an organic residue, R<1> is halogen atom, or an organic group, R<2> is hydrogen or halogen atom, C1-C4 alkyl or alkoxy group R<3> is hydrogen atom, C1-C4 alkyl or alkoxy group, benzyl or a methylene group and R4 is an organic residue. Said derivatives (Ia) and (Ib) are endowed with elastase inhibitory activity. A two-step process for their preparation starting from the corresponding 4-carboxy cephem or 3-carboxy penam is also provided. |