The invention provides compounds and pharmaceutically acceptable salts of Formula I wherein the variables A1, A2, R1, R2, V, W, X, Y, and Z are defined herein. Certain compounds of Formula I described herein which possess potent antiviral activity. The invention particularly provides compounds of Formula I that are potent and/or selective inhibitors of Hepatitis C virus replication. The invention also provides pharmaceutical compositions containing one or more compound of Formula I, or a salt, solvate, or acylated prodrug of such compounds, and one or more pharmaceutically acceptable carriers, excipients, or diluents. The invention further comprises methods of treating patients suffering from certain infectious diseases by administering to such patients an amount of a compound of Formula I effective to reduce signs or symptoms of the disease or disorder. These infectious diseases include viral infections, particularly HCV infections. The invention is particularly includes methods of treating human patients suffering from an infectious disease, but also encompasses methods of treating other animals, including livestock and domesticated companion animals, suffering from an infectious disease.Methods of treatment include administering a compound of Formula I as a single active agent or administering a compound of Formula I in combination with on or more other therapeutic agent.