A compound of formula I wherein X is O or S; X 1, X 2, X 3 and X 4 are each independently O or NH; R 1 and R 2 are independently Z 1 is N or CR a; Z 2 is NR b; R a is H, halogen, C 1-6 alkyl substituted with 0-6 R 5, C 3-6 cycloalkyl substituted with 0-6 R 5, CN, NO 2, OH, OR a1, SR a1, -C NR a1 R a1, -COOR a1, -OC R a1,-OC NR a1 R a1, -NR a1 R a1, -NR a1 C R a1, - NR a1 COOR a1, -NR a1 C NR a1 R a1,-NR a1 S 2 R a1, -NR a1 S 2 NR a1 R a1, -S R a1, - S NR a1 R a1, -S 2 R a1 or S 2 NR a1 R a1; R b is H, C 1-6 alkyl substituted with 0-6 R 5, C 3-6 cycloalkyl substituted with 0-6 R 5, -C R a1, -C NR a1 R a1, -S 2 R a1 or S 2 NR a1 R a1; R a1 is H or C 1-3 alkyl; R 3 is H, CH 3, halogen, NH 2 or OH; R 3a is H, CH 3, halogen, NH 2 or OH; or R 3 and R 3a may be taken together to form a 3-4 membered carbocycle; or R 3 and R 3a may be taken together to form a C=CH 2 substituent; R 5 is H, halogen, C 1-3 alkyl, CN, NO 2, OH, OR a1, SR a1, -C NR a1 R a1, -COOR a1,-OC R a1, -OC NR a1 R a1, -NR a1 R a1, -NR a1 C R a1, - NR a1 COOR a1,-NR a1 C NR a1 R a1, -NR a1 S 2 R a1, -NR a1 S 2 NR a1 R a1, -S R a1, - S NR a1 R a1,-S 2 R a1 or S 2 NR a1 R a1; R 5a is H or C 1-3 alkyl; R 6 is H, halogen, C 1-3 alkyl, CN, NO 2, OH, OR a1, SR a1, -C NR a1 R a1, -COOR a1,-OC R a1, -OC NR a1 R a1, -NR a1 R a1, -NR a1 C R a1, - NR a1 COOR a1,-NR a1 C NR a1 R a1, -NR a1 S 2 R a1, -NR a1 S 2 NR a1 R a1, -S R a1, - S NR a1 R a1,-S 2 R a1 or S 2 NR a1 R a1; R 8 is H, halogen, C 1-3 alkyl, CN, NO 2, OH, OR a1, SR a1, -C NR a1 R a1, -COOR a1,-OC R a1, -OC NR a1 R a1, -NR a1 R a1, -NR a1 C R a1, - NR a1 COOR a1,-NR a1 C NR a1 R a1, -NR a1 S 2 R a1, -NR a1 S 2 NR a1 R a1, -S R a1, - S NR a1 R a1,-S 2 R a1 or S 2 NR a1 R a1; R 9 is H, halogen or methyl; Y is CR 5 or N; m is 0, 1, 2 or 3; n is 0 or 1; or a pharmaceutically acceptable salt, tautomer or stereoisomer thereof. X is O or S; X 1, X 2, X 3 and X 4 are each independently O or NH; R 1 and R 2 are independently Z 1 is N or CR a; Z 2 is NR b; R a is H, halogen, C 1-6 alkyl substituted with 0-6 R 5, C 3-6 cycloalkyl substituted with 0-6 R 5, CN, NO 2, OH, OR a1, SR a1, -C NR a1 R a1, -COOR a1, -OC R a1,-OC NR a1 R a1, -NR a1 R a1, -NR a1 C R a1, - NR a1 COOR a1, -NR a1 C NR a1 R a1,-NR a1 S 2 R a1, -NR a1 S 2 NR a1 R a1, -S R a1, - S NR a1 R a1, -S 2 R a1 or S 2 NR a1 R a1; R b is H, C 1-6 alkyl substituted with 0-6 R 5, C 3-6 cycloalkyl substituted with 0-6 R 5, -C R a1, -C NR a1 R a1, -S 2 R a1 or S 2 NR a1 R a1; R a1 is H or C 1-3 alkyl; R 3 is H, CH 3, halogen, NH 2 or OH; R 3a is H, CH 3, halogen, NH 2 or OH; or R 3 and R 3a may be taken together to form a 3-4 membered carbocycle; or R 3 and R 3a may be taken together to form a C=CH 2 substituent; R 5 is H, halogen, C 1-3 alkyl, CN, NO 2, OH, OR a1, SR a1, -C NR a1 R a1, -COOR a1,-OC R a1, -OC NR a1 R a1, -NR a1 R a1, -NR a1 C R a1, - NR a1 COOR a1,-NR a1 C NR a1 R a1, -NR a1 S 2 R a1, -NR a1 S 2 NR a1 R a1, -S R a1, - S NR a1 R a1,-S 2 R a1 or S 2 NR a1 R a1; R 5a is H or C 1-3 alkyl; R 6 is H, halogen, C 1-3 alkyl, CN, NO 2, OH, OR a1, SR a1, -C NR a1 R a1, -COOR a1,-OC R a1, -OC NR a1 R a1, -NR a1 R a1, -NR a1 C R a1, - NR a1 COOR a1,-NR a1 C NR a1 R a1, -NR a1 S 2 R a1, -NR a1 S 2 NR a1 R a1, -S R a1, - S NR a1 R a1,-S 2 R a1 or S 2 NR a1 R a1; R 8 is H, halogen, C 1-3 alkyl, CN, NO 2, OH, OR a1, SR a1, -C NR a1 R a1, -COOR a1,-OC R a1, -OC NR a1 R a1, -NR a1 R a1, -NR a1 C R a1, - NR a1 COOR a1,-NR a1 C NR a1 R a1, -NR a1 S 2 R a1, -NR a1 S 2 NR a1 R a1, -S R a1, - S NR a1 R a1,-S 2 R a1 or S 2 NR a1 R a1; R 9 is H, halogen or methyl; Y is CR 5 or N; m is 0, 1, 2 or 3; n is 0 or 1; or a pharmaceutically acceptable salt, tautomer or stereoisomer thereof.