摘要 |
Compounds of formula (I) are in the preparation of antibacterial agents, wherein: R1 represents hydrogen, C1-C6 alkyl or C1-C6 alkyl substituted by one or more halogen atoms; R2 represents a group R10(X)n-(ALK)- wherein R10 represents hydrogen, a C1-C6 alkyl, C2-C6 alkenyl, C1-C6 alkynyl, cycloalkyl, aryl, or heterocyclyl group, any of which may be unsubstituted or substituted by (C1-C6)alkyl, (C1-C6)alkoyy, hydroxy, mercapto, (C1-C6)alkylthio, amino, halo, trifluoromethyl, cyano, nitro, -COOH, -CONH2, -COORA, -NHCORA, -CONHRA, -NHRA, -NRARB, or -CONRARB wherein RA and RB are independently a (C1-C6)alkyl group, and ALK represents a straight or branched divalent C1-C6 alkylene, C2-C6 alkenylene, or C2-C6 alkynylene radical, which may be interrupted by one or more non-adjacent -NH-, -O- or -S- linkages, X represents -NH-, -O- or -S-, and n is 0 or 1, R represents hydrogen or C1-C6 alkyl, R3 represents the characterising group or a natural or non-natural alpha amino acid in which any functional groups may be protected; and R4 represents an ester or thioester group.
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