Patent ID: 7834042

Claim:
A compound having the structure wherein Y is —Y 1 —Y 2 —Y 3 —Y 4 —Y 5 —; Y 1 is C(O) or C(R 1 R 2 ); Y 2 is O, C(O), P(O)(OH) or CH 2 , provided that when Y 1 is C(O), Y 2 is not C(O); R 1 is selected from the group consisting of hydrogen and C 1-4 alkyl; R 2 is selected from the group consisting of hydrogen, C 1-4 alkyl, and —OC(O)C 1-4 alkyl; Y 3 is O, C(O) or CH 2 , provided that when Y 2 is C(O), then Y 3 is not C(O), and further provided that when Y 2 is O, then Y 3 is not O; Y 4 is O or CH 2 or is absent, provided that when Y 3 is O, then Y 4 is not O; Y 5 is —(CH 2 ) 1-2 —(X) 0-1 —(CH 2 ) 0-1 — or is absent; X is —O— or —CR 3 R 4 —; and R 3 and R 4 are independently selected from the group consisting of hydrogen and C 1 -C 4 alkyl; or a pharmaceutically acceptable salt thereof.