The invention provides compounds of Formula (I): and pharmaceutically acceptable salts thereof. The compounds of Formula (I) inhibit protein kinase activity thereby making them useful as anticancer agents.本發明提供式(I)化合物:及其醫藥學上可接受之鹽。該等式(I)化合物抑制蛋白激酶活性,因此使其適用作抗癌劑。