| abstract |
The present invention relates to the compounds of formula (I) wherein one of the groups X1 to X4 is N and the others are CH; R is a group of formula (a), (b), (c), (d) or (e) in which n is zero or an integer of 1 to 5; R1 is hydrogen, halogen, C1-C6 alkyl, C1-C6 alkoxy, nitro or a group -NR4R5 wherein each of R4 and R5 is independently hydrogen or C1-C6 alkyl; R2 is hydrogen, C1-C6 alkyl or C1-C6 alkanoyl; R3 is hydrogen, halogen, hydroxy, C1-C6 alkoxy, carboxy, nitro or a group -NR4R5, wherein R4 and R5 are as defined above, and the pharmaceutically acceptable salts thereof. The compounds of formula (I) are useful as tyrosine kinase inhibitors. |