The present invention provides, among other things, compounds represented by the general Formula I:and pharmaceutically acceptable salts thereof, wherein X, Y, R1A, R1B, R2, and R3 are as defined in classes and subclasses herein and compositions (e.g., pharmaceutical compositions) comprising such compounds, which compounds are useful as inhibitors of hepatitis C virus polymerase, and thus are useful, for example, as medicaments for the treatment of HCV infection.特定言之,本發明提供由通式I表示之化合物:及其醫藥學上可接受之鹽,其中,X、Y、R1A、R1B、R2、及R3在本文中按類及亞類定義,還提供包含此等化合物之組合物(例如,醫藥組合物),該等化合物可用作C型肝炎病毒聚合酶之抑制劑,因此可用作(例如)用於治療HCV感染之藥劑。