Patent ID: 8871976

Claim:
A compound represented by the following structural formula: or a salt thereof, wherein: R is (C 1 -C 16 )alkyl, (C 2 -C 16 )alkenyl, (C 2 -C 16 )alkynyl, carbocyclyl or heterocyclyl, each of which is optionally substituted with one or more groups independently selected from the following: halo, NO 2 , —NHCO(C 1 -C 6 )alkyl, —OCO(C 1 -C 6 )alkyl, —COO(C 1 -C 6 )alkyl, (C 1 -C 10 )alkyl, halo(C 1 -C 10 )alkyl, (C 1 -C 10 )alkoxy, —S(C 1 -C 6 )alkyl, (C 3 -C 9 )cycloalkyl, aryl, and phenoxy, wherein each phenoxy or aryl are further optionally substituted with one or more groups selected from halo, NO 2 , (C 1 -C 10 )alkyl, halo(C 1 -C 10 )alkyl, and (C 1 -C 10 )alkoxy.