A compound of formula wherein R 1 is selected from C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 3 -C 6 cycloalkyl, aryl, and heteroaryl, each of which is optionally substituted; R 2 is selected from hydroxy, alkoxy, -X 2 -(CX 3)-(CR 6 R 7) m -X 2 -(CX 3)-R 8, -X 2 -(CX 3)-(CR 6 R 7) m -R 8, and -X 2 -(CX 3)-(CR 6 R 7) m -X 2 -R 18; R 6 and R 7 are independently selected from hydrogen, hydroxy, fluorine, chlorine, and C 1 -C 6 alkyl; R 8 is selected from C 1 -C 6 alkyl, fluoro C 1 -C 6 alkyl, heterocycloalkyl, aryl, heteroaryl, alkoxy, aryloxy, each of the foregoing is optionally substituted, hydroxy, and -NR 15 R 16; R 15 and R 16 are independently selected from hydrogen and C 1 -C 6 alkyl; or R 16 is COOR 17; R 17 is C 1 -C 6 alkyl; R 18 is selected from C 1 -C 6 alkyl, fluoro C 1 -C 6 alkyl, aryl, and heteroaryl, each of which is optionally substituted; each X 2 is independently selected from O, S and NR 15; X 3 is selected from O and S; R 3 and R 4 are independently a C 1 -C 6 alkyl; R 5 is selected from -(CR 9 R 10) n -R 11 and -(CR 12 =CR 13) n -R 14; R 9 and R 10 are independently selected from hydrogen and C 1 -C 6 alkyl; or alternatively R 9 and R 10, together with the carbon to which they are attached, form a C 3 -C 6 cycloalkyl; R 11 and R 14 are independently selected from C 1 -C 6 alkyl, C 3 -C 6 cycloalkyl, aryl, and heteroaryl, each of which is optionally substituted; R 12 and R 13 are independently selected from hydrogen, halogen, and C 1 -C 6 alkyl; X 1 is selected from O, NR 15 and S; and n and m are independently selected from 0 and an integer of 1-3, or a stereoisomer or a pharmaceutically acceptable salt thereof. R 1 is selected from C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 3 -C 6 cycloalkyl, aryl, and heteroaryl, each of which is optionally substituted; R 2 is selected from hydroxy, alkoxy, -X 2 -(CX 3)-(CR 6 R 7) m -X 2 -(CX 3)-R 8, -X 2 -(CX 3)-(CR 6 R 7) m -R 8, and -X 2 -(CX 3)-(CR 6 R 7) m -X 2 -R 18; R 6 and R 7 are independently selected from hydrogen, hydroxy, fluorine, chlorine, and C 1 -C 6 alkyl; R 8 is selected from C 1 -C 6 alkyl, fluoro C 1 -C 6 alkyl, heterocycloalkyl, aryl, heteroaryl, alkoxy, aryloxy, each of the foregoing is optionally substituted, hydroxy, and -NR 15 R 16; R 15 and R 16 are independently selected from hydrogen and C 1 -C 6 alkyl; or R 16 is COOR 17; R 17 is C 1 -C 6 alkyl; R 18 is selected from C 1 -C 6 alkyl, fluoro C 1 -C 6 alkyl, aryl, and heteroaryl, each of which is optionally substituted; each X 2 is independently selected from O, S and NR 15; X 3 is selected from O and S; R 6 and R 7 are independently selected from hydrogen, hydroxy, fluorine, chlorine, and C 1 -C 6 alkyl; R 8 is selected from C 1 -C 6 alkyl, fluoro C 1 -C 6 alkyl, heterocycloalkyl, aryl, heteroaryl, alkoxy, aryloxy, each of the foregoing is optionally substituted, hydroxy, and -NR 15 R 16; R 15 and R 16 are independently selected from hydrogen and C 1 -C 6 alkyl; or R 16 is COOR 17; R 17 is C 1 -C 6 alkyl; R 18 is selected from C 1 -C 6 alkyl, fluoro C 1 -C 6 alkyl, aryl, and heteroaryl, each of which is optionally substituted; each X 2 is independently selected from O, S and NR 15; X 3 is selected from O and S; R 3 and R 4 are independently a C 1 -C 6 alkyl; R 5 is selected from -(CR 9 R 10) n -R 11 and -(CR 12 =CR 13) n -R 14; R 9 and R 10 are independently selected from hydrogen and C 1 -C 6 alkyl; or alternatively R 9 and R 10, together with the carbon to which they are attached, form a C 3 -C 6 cycloalkyl; R 11 and R 14 are independently selected from C 1 -C 6 alkyl, C 3 -C 6 cycloalkyl, aryl, and heteroaryl, each of which is optionally substituted; R 12 and R 13 are independently selected from hydrogen, halogen, and C 1 -C 6 alkyl; X 1 is selected from O, NR 15 and S; and n and m are independently selected from 0 and an integer of 1-3, R 9 and R 10 are independently selected from hydrogen and C 1 -C 6 alkyl; or alternatively R 9 and R 10, together with the carbon to which they are attached, form a C 3 -C 6 cycloalkyl; R 11 and R 14 are independently selected from C 1 -C 6 alkyl, C 3 -C 6 cycloalkyl, aryl, and heteroaryl, each of which is optionally substituted; R 12 and R 13 are independently selected from hydrogen, halogen, and C 1 -C 6 alkyl; X 1 is selected from O, NR 15 and S; and n and m are independently selected from 0 and an integer of 1-3,