Patent ID: 7335772

Claim:
A compound of formula (IV) and salts thereof: wherein R 1 is selected from the group consisting of: hydrogen; a straight or branched chain alkyl of one to 10 carbon atoms, optionally substituted with a substituent selected from the group consisting of lower alkyl, cycloalkyl of 3 to 6 carbon atoms, wherein said cycloalkyl is optionally substituted with a lower alkyl group; straight or branched chain alkenyl of 2 to 10 carbon atoms, and wherein the straight or branched chain alkyl is optionally substituted with a substituent selected from the group consisting of lower alkyl, cycloalkyl of 3 to 6 carbon atoms, wherein said cycloalkyl is optionally substituted with a lower alkyl group; hydroxyalkyl of one to six carbon atoms; acyloxyalkyl wherein the acyloxy moiety is alkanoyloxy of two to four carbon atoms or benzoyloxy and the alkyl moiety contains one to six carbon atoms; benzyl; (phenyl)ethyl; and phenyl, wherein said benzyl, (phenyl)ethyl and phenyl substituents are optionally substituted on the benzene ring by one or two moieties independently selected from the group consisting of lower alkyl, lower alkoxy, and halogen, with the proviso that when the benzene ring is substituted by two such moieties, then the moieties together contain more than 6 carbon atoms; R 2 is selected from the group consisting of: hydrogen; straight or branched chain alkyl containing one to eight carbon atoms; benzyl; (phenyl)ethyl; and phenyl, wherein said benzyl, (phenyl)ethyl and phenyl substituents are optionally substituted on the benzene ring by one or two moieties independently selected from the group consisting of lower alkyl, lower alkoxy, and halogen, with the proviso that when the benzene ring is substituted by two such moieties, then the moieties together contain more than 6 carbon atoms; R is independently selected from the group consisting of: alkoxy of one to four carbon atoms; alkyl of one to four carbon atoms; and halogen; and n is an integer from 0 to 2, with the proviso that if n is 2, then said groups together contain no more than 6 carbon atoms.