A compound of structural formula I: or a pharmaceutically acceptable salts thereof; wherein W is selected from the group consisting of C 1 -C 6 alkyl, -OC 1 -C 6 alkyl, -NHC 1 -C 6 alkyl or when taken together with R 1, W-R 1 is hydrogen; X-Y is selected from the group consisting of -CH=CH-, -(CH 2) m CR 3 R 4 (CH 2) n -and -C R 3 R 4 C -; R 1 is selected from the group consisting of aryl, heterocycle, aroyl, heteroaroyl, C 3 -C 10 cycloalkyl, C 2 -C 6 alkenyl and C 2 -C 6 alkynyl; wherein the aryl, heterocycle, aroyl, heteroaroyl and C 1 -C 10 cycloalkyl are unsubstituted or substituted with 1-3 substituents from R 5 or when taken together with W, W-R 1 is hydrogen; R 2 is selected from the group consisting of C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2 -C 6 alkynyl, C 1 -C 10 cycloalkyl, benzyl, heterocycle and C 1 -C 6 alkylheterocycle; wherein the C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2 -C 6 alkynyl, C 1 -C 10 cycloalkyl, benzyl, heterocycle and C 1 -C 6 alkylheterocycle are unsubstituted or substituted with 1-3 substituents each independently selected from R 3, R 4 and R 5; R 3 and R 4 are independently selected from the group consisting of hydrogen, C 1 -C 6 alkyl, C 1 -C 6 alkylC 3 -C 10 cycloalkyl, benzyl and aryl, wherein the C 1 -C 6 alkylC 3 -C lO cycloalkyl, benzyl and aryl are unsubstituted or substituted with R 5, or when taken together R 3, R 4 and the carbon on which they are attached form a C 1 -C 10 cycloalkyl or a 4-membered heterocycle; and R 5 is selected from the group consisting of hydrogen, halogen, C 1 -C 6 alkyl, halogen-substitutedC 1 -C 6 alkyl, -OH, C 1 -C 6 alkylOH, halogen-substitutedC 1 -C 6 alkylOH, -OC 1 -C 6 alkyl, -Ohalogen-substitutedC 1 -C 6 alkyl, -COOH, -COOC 1 -C 6 alkyl, -C 1 -C 6 alkylCOOC 1 -C 6 alkyl, -C 1 -C 6 alkylCOOH, -OC 1 -C 6 alkylCOOH, -CN, C 1 -C 6 alkylCN, NH 2, NHC 1 -C 6 alkyl, N(C 1 -C 6 alkyl) 2, -NHCOOC 1 -C 6 alkyl, C 1 -C 6 alkylCONH 2, -CONH 2, -CONHC 1 -C 6 alkyl, -NHCOC 1 -C 6 alkyl, -CON(C 1 -C 6 alkyl) 2, -NHSO 2 C 1 -C 6 alkyl, SO 2 aryl -SO 2 C 1 -C 6 alkyl, C 1 -C 6 alkyl SO 2 C 1 -C 6 alkyl, aryl, -NHCOaryl, and -NHCOheterocycle; m and n are independently 0-3, wherein m+n > 0. W is selected from the group consisting of C 1 -C 6 alkyl, -OC 1 -C 6 alkyl, -NHC 1 -C 6 alkyl or when taken together with R 1, W-R 1 is hydrogen; X-Y is selected from the group consisting of -CH=CH-, -(CH 2) m CR 3 R 4 (CH 2) n -and -C R 3 R 4 C -; R 1 is selected from the group consisting of aryl, heterocycle, aroyl, heteroaroyl, C 3 -C 10 cycloalkyl, C 2 -C 6 alkenyl and C 2 -C 6 alkynyl; wherein the aryl, heterocycle, aroyl, heteroaroyl and C 1 -C 10 cycloalkyl are unsubstituted or substituted with 1-3 substituents from R 5 or when taken together with W, W-R 1 is hydrogen; R 2 is selected from the group consisting of C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2 -C 6 alkynyl, C 1 -C 10 cycloalkyl, benzyl, heterocycle and C 1 -C 6 alkylheterocycle; wherein the C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2 -C 6 alkynyl, C 1 -C 10 cycloalkyl, benzyl, heterocycle and C 1 -C 6 alkylheterocycle are unsubstituted or substituted with 1-3 substituents each independently selected from R 3, R 4 and R 5; R 3 and R 4 are independently selected from the group consisting of hydrogen, C 1 -C 6 alkyl, C 1 -C 6 alkylC 3 -C 10 cycloalkyl, benzyl and aryl, wherein the C 1 -C 6 alkylC 3 -C lO cycloalkyl, benzyl and aryl are unsubstituted or substituted with R 5, or when taken together R 3, R 4 and the carbon on which they are attached form a C 1 -C 10 cycloalkyl or a 4-membered heterocycle; and R 5 is selected from the group consisting of hydrogen, halogen, C 1 -C 6 alkyl, halogen-substitutedC 1 -C 6 alkyl, -OH, C 1 -C 6 alkylOH, halogen-substitutedC 1 -C 6 alkylOH, -OC 1 -C 6 alkyl, -Ohalogen-substitutedC 1 -C 6 alkyl, -COOH, -COOC 1 -C 6 alkyl, -C 1 -C 6 alkylCOOC 1 -C 6 alkyl, -C 1 -C 6 alkylCOOH, -OC 1 -C 6 alkylCOOH, -CN, C 1 -C 6 alkylCN, NH 2, NHC 1 -C 6 alkyl, N(C 1 -C 6 alkyl) 2, -NHCOOC 1 -C 6 alkyl, C 1 -C 6 alkylCONH 2, -CONH 2, -CONHC 1 -C 6 alkyl, -NHCOC 1 -C 6 alkyl, -CON(C 1 -C 6 alkyl) 2, -NHSO 2 C 1 -C 6 alkyl, SO 2 aryl -SO 2 C 1 -C 6 alkyl, C 1 -C 6 alkyl SO 2 C 1 -C 6 alkyl, aryl, -NHCOaryl, and -NHCOheterocycle; m and n are independently 0-3, wherein m+n > 0.