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.