N-formyl hydroxylamine derivatives as antibacterial agents

A method for the treatment of bacterial infections in humans and non-human mammals, which comprises administering to a subject suffering such infection an antibacterially effective dose of an antibacterial pharmaceutical or veterinary composition comprising a compound of formula (I) or a pharmaceutically or veterinarily acceptable salt, hydrate or solvate thereof, and a pharmaceutically or veterinarily acceptable excipient or carrier:

• 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, C2-C6 alkynyl, cycloalkyl, aryl, or heterocyclyl group, any of which may be unsubstituted or substituted by (C1-C6)alkyl, (C1-C6)alkoxy, 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 of a natural or non-natural α amino acid in which any functional groups may be protected;
• and
• R4 represents an ester or thioester group.