Provided are a series of novel pyridine or pyrimidine derivatives of formula I which inhibit CDK9 and may be useful for the treatment of hyperproliferative diseases. In particular the compounds are of use in the treatment of proliferative diseases such as cancer including hematological malignancies such as acute myeloid leukemia, multiple myeloma, chronic lymphocytic leukemia, diffuse large B cell lymphoma, Burkitt's lymphoma, follicular lymphoma and solid tumors such as breast cancer, lung cancer, neuroblastoma and colon cancer.A is C(R5 ) or N；R5 is H, C1 - 3 alkyl, CN or halogen；R2 is optionally substituted 3-7 membered heterocycloalkyl or 3-7 membered cycloalkyl；R4 iswherein X and Y together with the atoms to which they are attached form an optionally substituted, saturated or partially saturated 5 to 7 membered heterocycloalkyl ring which, in addition to the bridge nitrogen, may contain one or two heteroatoms selected from N, O and S；J is N or CR11 ； andR11 is H or C1 - 3 alkyl.
