HCV NS5B Inhibitors

A compound of formula I

• wherein:
• R1 is CO2R5 or CONR6R1;
• R2 is furanyl, pyrrolyl, thienyl, pyrazolyl, oxazolyl, thiazolyl, isoxazolyl, isothiazolyl, oxadiazolyl, triazolyl, or tetrazolyl, and is substituted with 0-2 substituents selected from oxo, amino, alkylamino, dialkylamino, alkyl, (cycloalkyl)alkyl, hydroxyalkyl, (tetrahydrofuranyl)alkyl, (tetrahydropyranyl)alkyl, (CO2R5)alkyl, (CON(R5)2)alkyl, (COR9)alkyl, (alkylsulfonyl)alkyl, and ((R9)alkyl)CON(R5);
• R3 is C5-7cycloalkyl;
• R4 is hydrogen, halo, hydroxy, alkyl, or alkoxy;
• R5 is hydrogen, alkyl, or cycloalkyl;
• R6 is hydrogen, alkyl, cycloalkyl, alkoxy, or SO2R8;
• R7 is hydrogen, alkyl, or cycloalkyl;
• or NR6R7 taken together is pyrrolidinyl, piperidinyl, piperazinyl, N-alkylpiperazinyl, homomorpholinyl, homopiperidinyl, morpholinyl, or thiomorpholinyl;
• R8 is alkyl, haloalkyl, cycloalkyl, amino, alkylamino, dialkylamino, or phenyl;
• or R8 is pyrrolidinyl, piperidinyl, piperazinyl, N-alkylpiperazinyl, homomorpholinyl, homopiperidinyl, morpholinyl, or thiomorpholinyl;
• R9 is pyrrolidinyl, piperidinyl, piperazinyl, N-alkylpiperazinyl, homomorpholinyl, homopiperidinyl, morpholinyl, or thiomorpholinyl;
• and
• (a) is a single bond or a double bond, (b) is a single bond or a double bond, provided that at least one of (a) and (b) is a single bond;
• or a pharmaceutically acceptable salt thereof.