Patent ID: 7534905

Claim:
A compound having the formula wherein X 3 is selected from a group consisting of O and C(R 4 )(R 5 ); X 1 and X 2 are N—R, or one of X 1 and X 2 is O and the other is N—R; each of C a and C b is independently selected from the group consisting of an achiral center, an (S) chiral center and an (R) chiral center; R a and R b are (i) each independently selected from a group consisting of C 1-10 alkyl, C 6-10 aryl, C 3-9 heteroaryl, or (ii) taken together to form a C 3 -C 4 alkylene chain which together with C a and C b forms a 5-membered aliphatic ring and a 6-membered aliphatic ring; R c and R d are each independently selected from the group consisting of hydrogen, C 1-10 alkyl, C 6-10 aryl, and C 3-9 heteroaryl; R 6 is selected from the group consisting of halogen, hydrogen, C 1-10 alkyl, C 6-10 aryl, C 3-9 heteroaryl, C 1-10 alkoxy, C 6-10 aryloxy, C 1-10 dialkylamino, C 1-10 alkyl-C 6-10 arylamino, C 6-10 diarylamino, —O—C(R 9 )═C(R 7 )(R 8 ), —OSO 2 CF 3 and —SR; R is selected from the group consisting of C 1-10 alkyl, C 6-10 aryl, and C 3-9 heteroaryl; and each of, R 1 , R 2 , R 3 , R 4 , R 5 , R 7 , R 8 , and R 9 is independently selected from the group consisting of hydrogen, C 1-10 alkyl, C 6-10 aryl, C 3-9 heteroaryl, C 1-10 alkoxy, C 6-10 aryloxy, C 1-10 dialkylamino, C 1-10 alkyl-C 6-10 arylamino, C 6-10 diarylamino, and halogen.