Patent ID: 6949566

Claim:
A compound of the formula (I): wherein R 1 is NHOH, hydroxy, or lower alkyloxy; R 2 is hydrogen atom, optionally substituted lower alkyl, optionally substituted aryl, optionally substituted aralkyl, optionally substituted heteroaryl, or optionally substituted heteroarylalkyl; R 3 is hydrogen atom, optionally substituted lower alkyl, optionally substituted aryl, optionally substituted aralkyl, optionally substituted heteroaryl, or optionally substituted heteroarylalkyl; R 4 is optionally substituted arylene, or optionally substituted heteroarylene; R 5 is: R 6 is optionally substituted aryl, optionally substituted heteroaryl or optionally substituted non-aromatic heterocyclic group; provided that R 5 is thiazole-2,5-diyl when R 4 is thiophene-2,5-diyl and R 6 is optionally substituted phenyl; or an optically active isomer, prodrug, pharmaceutically acceptable salt, or solvate thereof.