Patent ID: 8916560

Claim:
A compound having structural formula IV: or a salt, ester or prodrug thereof, wherein: Rz is OH; R 1 is phenyl and has one or more substituents chosen from hydrogen, halo, alkyl, alkenyl, alkynyl, cycloalkyl, haloalkyl, aryl, aralkyl, heterocyclyl, heteroaryl, heterarylalkyl, CN, alkoxy, alkylamino, dialkylamino, NHSO 2 R 12 , NHSO 2 NHR 12 , NHCOR 12 , NHCONHR 12 , CONHR 12 , CONR 12a R 12b , hydroxy and OCF 3 ; R 3 is hydrogen; R 5 and R 6 are independently C 1 -C 6 alkyl; and R 12 , R 12a and R 12b are independently chosen from hydrogen, C 1 -C 6 alkyl, aryl, heteroaryl, aralkyl, CF 3 and heteroaralkyl, any of which may be optionally substituted.