Patent ID: 7105527

Claim:
A compound of the following formula: or a pharmaceutically acceptable salt thereof, wherein i) X is O; ii) R 1 is fluorine; iii) R 2 is chosen from C2–C8 alkenyl, C2–C8 alkynyl, cycloalkyl, aminoalkyl, hydroxyalkyl, haloalkyl, heteroaryl, and C 6 H 4 R 6 wherein R 6 is chosen from F, Cl, Br, I, CN, CF 3 , N 3 CH 3 , ethyl, t-butyl, haloalkyl, aminoalkyl, CH 3 O, alkenyl, alkynyl, and aryl; iv) R 3 and R 3 ′ are chosen independently from hydrogen and halogen; v) R 4 is H, phosphate, carbonyl substituted with alkyl, alkenyl, alkynyl, aryl, or other pharmaceutically acceptable leaving group, which, when administered in vivo, is capable of providing a compound wherein R 4 is H or phosphate.