Hydroxamic acid derivatives as antibacterials

A method for the treatment of bacterial infections in humans and non-human mammals, which comprises inhibiting bacterial growth by administering to a subject an antibacterially effective dose of a compound of formula (I) or a pharmaceutically or veterinarily acceptable salt thereof:

• wherein:
• R1 represents hydrogen, or C1-C6 alkyl, C1-C6 alkyl substituted by one or more halogen atoms, amino, hydroxy, or C1-C6 alkoxy;
• R2 represents a group R10—(X)n—(ALK)m— wherein
• R10 represents hydrogen, or 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, and may be interrupted by one or more non-adjacent —NH—, —O— or —S— linkages,
• X represents —NH—, —O—, or —S—, and
• m and n are independently 0 or 1;
• and
• A represents (i) a group of formula (IA), (IB), (IC), or (ID)
• wherein:
• R3 represents hydrogen or C1-C6 alkyl and R4 represents the side chain of a natural or non-natural alpha amino acid or R3 and R4 when taken together with the nitrogen and carbon atoms to which they are respectively attached form an optionally substituted saturated heterocyclic ring of 5 to 8 atoms which ring is optionally fused to a carbocyclic or second heterocyclic ring,
• PROVIDED THAT the fragment of fragment
• in (IA) is not a fragment of formula
• R5 and R6,independently represent hydrogen, or optionally substituted C1-C8 alkyl, cycloalkyl, aryl, aryl (C1-C6 alkyl), heterocyclic, or heterocyclic (C1-C6 alkyl), or R5 and R6 when taken together with the nitrogen atom to which they are attached form an optionally substituted saturated heterocyclic ring of 3 to 8 atoms which ring is optionally fused to a carbocyclic or second heterocyclic ring, and
• R7 represents hydrogen, C1-C6 alkyl, or an acyl group.
• PROVIDED THAT (a) R5 and R6 taken together with the nitrogen atom to which they are attached do not form an optionally substituted saturated heterocyclic ring of 3 to 8 atoms when R1 and R3 are hydrogen, R2 is hydrogen, C1-C6 alkyl, phenyl, benzyl, 4-chlorophenylmethyl, 4-nitrophenylmethyl, or 4-aminophenylmethyl and R3 is hydrogen, methyl, isopropyl, isobutyl or benzyl;
• and (b) R5 is not 2-pyridyl or 2-thiazolyl when R1, R3 and R6 are hydrogen, R2 is n-pentyl and R4 is isopropyl;
• and (c) R5 and R6 are not both ethyl when R1 and R3 are hydrogen, R2 is n-pentyl and R4 is methyl or isopropyl.