Patent ID: 8318738

Claim:
A compound having formula (VI) wherein, R a is a phenyl group; a substituted phenyl group having one or more substituents wherein the one or more substituents are independently selected from one or more of amino, amidino, guanidino, hydrazino, amidazonyl, C 1-4 alkylamino, C 1-4 dialkylamino, halogen, perfluoro C 1-4 alkyl, C 1-4 alkyl, C 1-3 alkoxy, nitro, carboxy, cyano, sulfuryl, and hydroxyl groups; or a bicyclic aryl group having 8 to 11 ring members, which may have 1 to 3 heteroatoms selected from nitrogen, oxygen and sulfur; R b is a monocyclic aryl group having 5 to 7 ring members, which may have 1 to 2 heteroatoms selected from nitrogen, oxygen or sulfur, and aryl ring in the compound may have one or more substituents selected from a group consisting of halogen, hydroxy, cyano, lower alkyl, and lower alkoxy groups; R c is a saturated or unsaturated C 1-6 alkyl, C 1-6 alkoxy, perfluoro C 1-6 alkyl group; and X 1 , X 2 , and X 3 may be the same or different and independently selected from hydrogen, hydroxyl, and halide; and wherein the compound of formual (VI) is substituted with hydrogen or methyl at the 9-position.