| abstract |
Rifamycin antibiotic derivatives of formulae (I) and (Ia) bearing at the position 36 a substituent selected from (C1-C8)alkyl, halo, hydroxy, (C1-C4)acyloxy, (C1-C4)alkoxy, (C1-C4)alkylthio, (C1-C4)alkylamino, di(C1-C4)alkylamino and substituted 4-oxo-3-pyridinyl carbonyloxy of formula (1) obtained by reacting rifamycin with suitably substituted malonic acid. The compounds of the invention are antimicrobial agents mainly active against gram positive bacteria and fastidious gram negative bacteria showing also considerable antimicrobial activity against the rifampicin resistant microbial strains. |