Fused pyrimidines of formula (I): wherein A, n, R1, R2, and R3 have any of the values defined herein and the pharmaceutically acceptable salts thereof have activity as inhibitors of PI3K and may thus be used to treat diseases and disorders arising from abnormal cell growth, function or behavior associated with PI3 kinase such as cancer, immune disorders, cardiovascular disease, viral infection, inflammation, metabolism/endocrine disorders and neurological disorders. Processes for synthesizing the compounds are also described.
