Compounds of the formula (I), in which X
1
, X
2
, X
3
, X
4
, R
1
, R
2
, R
3
and R
4
have the meanings indicated in Claim
1
, are inhibitors of tyrosine kinases, in particular Met kinase, and can be employed, inter alia, for the treatment of tumours.
式(I)的化合物,其中X1、X2、X3、X4、R1、R2、R3和R4具有权利要求1所示的含义,是
酪氨酸激酶的
抑制剂,特别是Met激酶的
抑制剂,可以用于治疗肿瘤等疾病。