A compound of formula ** Formula ** wherein Ra is H； C1-4alkyl； or C1-4alkyl substituted with OH, NH2, NHC1-4alkyl or N (di-C1-4alkyl) 2； Rb is H； halogen； C1-6alkyl； or C1-6alkoxy, and R is a radical of formula (b) where R3 is a radical of formula α -X-Rc-Y where X is a direct bond, O, S or NR11 where R11 is H or C1 -4 alkyl, Rc is C1-4 alkylene or C1-4 alkylene where one CH2 is replaced by CRxRy where one of Rx and Ry is H and the other is CH3, each of Rx and Ry is CH3 or Rx and Ry together form -CH2-CH2-, and Y is -NR12R13 where each of R12 and R13, independently, is H, C3-6 cycloalkyl, C3-6 cycloalkyl-C1-4 alkyl, phenyl, naphthyl, (phenyl- or naphthyl) -C1-4 alkyl, (pyridyl- or pyrimidinyl) -C1-4 alkyl, C2-6 alkenyl or C1-4 alkyl optionally substituted on the terminal carbon atom with OH, halogen, C1-4 alkoxy or -NR14R15 in where each of R14 and R15 is independently H, C1-4 alkyl, C3-6 cycloalkyl, C3-6 cycloalkyl-C1-4 alkyl, (phenyl- or naphthyl) C1-4 alkyl, or R12 and R13 form together with the nitrogen atom to which 1,4-piperazinyl, 2-C1-4 alkyl- or - C3-6 cycloalkyl-1-pipera are attached zinyl； 3-C1-4 alkyl- or -C3-6 cycloalkyl-1-piperazinyl； 2,2- or 3,5- or 2,5- or 2,6-di (C1-4 alkyl) -1-piperazinyl； 3,4,5-tri (C1-4 alkyl) -1-piperazinyl； 4-N- (C1-4 alkyl) - or - (ω-hydroxy-C1-4 alkyl) - or - (ω-dimethylamino-C1-4 alkyl) -1-piperazinyl； 4-N-pyridin-4-yl-1-piperazinyl； 4-N-phenyl- or -C3-6 cycloalkyl-1-piperazinyl； 4-N- (C1-4 alkyl) - or - (α- hydroxy-C1-4 alkyl) -3-C1-4 alkyl- or 3,3-di (C1-4 alkyl) -1-piperazinyl； 4-N- (1-C1-4 alkyl-C3-6 cycloalkyl) -1-piperazinyl； 4- N-formyl-1-piperazinyl； 4-N-pyrimidin-2-yl-1-piperazinyl； and R4 is H； halogen； C1-4alkyl； C1-4alkoxy； CF3； nitrile； nitro or amino, or a salt thereof.Un compuesto de fórmula **Fórmula**en donde Ra es H； C1-4alquilo； o C1-4alquilo sustituido con OH, NH2, NHC1-4alquilo o N (di-C1-4alquilo)2； Rb es H； halógeno； C1-6alquilo； o C1-6alcoxi, y R es un radical de fórmula (b) en donde R3 es un radical
