Patent ID: 8138219

Claim:
A compound of structural formula I: or a pharmaceutically acceptable salt thereof, wherein: X is selected from the group consisting of: (1) —O—, (2) —NH—, (3) —S—, (4) —SO 2 —, (5) —CH 2 —, (6) —CHF—, (7) —CF 2 —, (8) —CH(OH)—, (9) —CO—, (10) —NHCO—, (11) —CONH—, and (12) —CO 2 —; R 1 is selected from the group consisting of: (1) -hydrogen, and (2) —C 1-3 alkyl; R 2 is selected from the group consisting of: (1) —C 1-6 alkyl, (2) —C 3-7 cycloalkyl, (3) —C 2-6 cycloheteroalkyl, (4) phenyl, (5) naphthyl, and (6) heteroaryl, wherein each alkyl, cycloalkyl, cycloheteroalkyl, phenyl, naphthyl and heteroaryl is unsubstituted or substituted with 1, 2 or 3 substituents selected from —C 1-6 alkyl, —C 3-7 cycloalkyl, halogen, —CF 3 , —OCF 3 , —CN, —SO 2 R 7 , —CO 2 R 8 , phenyl, —C 2-6 cycloheteroalkyl, —OR 7 , —SR 7 , —CONHR 8 , —NHSO 2 R 7 , and —NHCOR 7 ; R 3 and R 4 are each independently selected from the group consisting of: (1) hydrogen, (2) halogen, (3) —C 1-6 alkyl, (4) —OC 1-6 alkyl, (5) —CN, (6) —OR 7 , (7) —SO 2 R 7 , (8) —SR 7 , (9) —N(R 8 ) 2 , (10) —CONHR 8 , (11) —NHSO 2 R 7 , and (12) —NHCOR 7 , wherein each alkyl is unsubstituted or substituted on each carbon with 1, 2 or 3 substituents selected from halogen, —C 1-6 alkyl, —C 3-7 cycloalkyl, —CF 3 , —OCF 3 , —CN, —SO 2 R 7 , —CO 2 R 8 , phenyl, —C 2-6 cycloheteroalkyl, —OR 7 , —SR 7 , —CONHR 8 , —NHSO 2 R 7 , and —NHCOR 7 ; R 5 is selected from the group consisting of: (1) —C 1-6 alkyl, (2) —C 1-6 alkenyl, (3) phenyl, and (4) benzyl, wherein each alkyl, alkenyl, phenyl and benzyl is unsubstituted or substituted on each carbon with 1, 2 or 3 substituents selected from: halogen, —C 1-6 alkyl, —C 3-7 cycloalkyl, —CF 3 , —OCF 3 , —CN, —SO 2 R 7 , —CO 2 R 8 , phenyl, —C 2-6 cycloheteroalkyl, —OR 7 , —SR 7 , —CONHR 8 , —NHSO 2 R 7 , and —NHCOR 7 ; R 6 is selected from the group consisting of: (1) hydrogen, and (2) —C 1-4 alkyl; R 7 is selected from the group consisting of: (1) —C 1-6 alkyl, and (2) —C 3-6 cycloalkyl; and R 8 is selected from the group consisting of: (1) hydrogen, (2) —C 1-6 alkyl, and (3) —C 3-6 cycloalkyl.