Patent ID: 8236282

Claim:
A compound of formula I or a pharmaceutically acceptable salt, hydrate, solvate or prodrug of the compound, wherein: R 1 is hydrogen, —OH, —NO 2 , —CN, —COOR, —OCH 2 OR, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2 -C 6 alkynyl, C 1 -C 6 alkoxy or halo; R is C 1 -C 6 alkyl; R 2 is a radiofluoro; R 3 is hydrogen, C 1 -C 6 alkyl, C 2 -C 6 alkenyl or C 2 -C 6 alkynyl; and R 4 is hydrogen, C 1 -C 6 alkyl, C 2 -C 6 alkenyl or C 2 -C 6 alkynyl.