Patent ID: 7888367

Claim:
A compound of formula I wherein: R 1 is independently H, —OR 3 , —NHR 4 ; C 1 -C 4 alkyl; or, when n is 2, adjacent R 1 can together define an olefinic bond; R 2 is H; or when R 1 and R 2 form gem substitution on the same carbon and R 1 is C 1 -C 4 alkyl, then R 2 is C 1 -C 4 alkyl; or when R 1 and R 2 form gem substitution on the same carbon and R 1 is —OR 3 , then R 2 is —C(═O)OH or a pharmaceutically acceptable ester thereof; R 3 is independently H, or a pharmaceutically acceptable ester thereof; R 4 is independently H or a pharmaceutically acceptable amide thereof; R 5 is H; R 6 is H; n is 1, 2 or 3; and pharmaceutically acceptable salts thereof.