Novel antibacterial agents and potentiators of carbapenem antibiotics

A compound of the formula:

• ##STR53## wherein:
• R.sub.1 is H, CH.sub.3 ;
• R.sub.5 is
• (a) hydrogen,
• (b) C.sub.1 -C.sub.12 linear or branched alkyl;
• (c) C.sub.2 -C.sub.12 linear or branched monoalkenyl;
• (d) C.sub.7 -C.sub.20 aralkyl, wherein the alkyl chain is linear or branched C.sub.1 -C.sub.8 ;
• (e) heterocyclylalkyl, wherein the alkyl chain is linear or branched C.sub.1 -C.sub.8 and the heterocyclyl ring is 5-6 membered, optionally fused with a benzene ring, fully aromatic, containing 1-2 O, N or S heteroatoms;
• wherein said above values for R.sub.5 can be substituted by one or more:
• halo, hydroxy, carboxy, C.sub.1 -C.sub.4 alkoxycarbonyl, C.sub.7 -C.sub.16 arylalkoxycarbonyl, C.sub.3 -C.sub.7 cycloalkyl, C.sub.1 -C.sub.4 alkoxy, C.sub.6 -C.sub.12 aryloxy, amino, mono- or di-C.sub.1 -C.sub.8 alkylamino, thio, C.sub.1 -C.sub.4 alkylthio, C.sub.6 -C.sub.12 arylthio, C.sub.7 -C.sub.16 aralkylthio, or the radical --S--(CH.sub.2).sub.n --CH(NH.sub.2)COOH, where n=1-2;
• with the proviso that R.sub.5 is at least C.sub.2 alkyl if substituted by one of the above-defined thio groups, and wherein the aryl or aromatic heterocyclyl rings can be further substituted by C.sub.1 -C.sub.4 linear or branched alkyl, trihalomethyl, nitro, cyano, halo, or sulfonamido;
• R.sub.3 and R.sub.4 are hydrogen, C.sub.1 -C.sub.4 alkyl, C.sub.6 -C.sub.12 aryl or C.sub.7 -C.sub.16 aralkyl;
• and including stereoisomers and racemates thereof.