Patent ID: 7947671

Claim:
A compound of formula: wherein R a and R b together with the carbon to which they are attached form a group: —C(═O)—; —CHOX 1 or —CHNX 1 X 2 where each X 1 and X 2 is independently selected from hydrogen, substituted or unsubstituted C 1 -C 18 alkyl, substituted or unsubstituted C 2 -C 18 alkenyl, substituted or unsubstituted C 2 -C 18 alkynyl, substituted or unsubstituted aryl, protecting group, and —C(═O)R′ wherein R′ is selected from hydrogen, OH, NO 2 , NH 2 , SH, CN, halogen, C 1 -C 6 alkyl, alkenyl, alkynyl, aryl, aralkyl and heterocyclic; or a group of formula: wherein R d and X 1 are independently selected from hydrogen, substituted or unsubstituted R′, OR′, —(C═O)R′, substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aryl, and substituted or unsubstituted aralkyl; wherein R′ is selected from the group consisting of hydrogen, OH, NO 2 , NH 2 , SH, CN, halogen, C(═O)H, C(═O)CH 3 , CO 2 H, CO 2 CH 3 , C 1 -C 6 alkyl, alkenyl, alkynyl, aryl, aralkyl and heterocyclic; R 7 is —OCH 3 and R 8 is —OH or R 7 and R 8 together form a group —O—CH 2 —O—; R 12b is H, substituted or unsubstituted alkyl, haloalkyl, alcoxyalkyl, haloalkoxyalkyl, arylalkylene, haloalkylarylalkylene, acyl, haloacyl, carbonate, carbamate, arylalkyl, alkenyl or amino acid; R 21 is —H, OH or CN; R 5 and R 18 are —OX 1 , wherein each X 1 is independently selected from hydrogen, substituted or unsubstituted C 1 -C 18 alkyl, substituted or unsubstituted C 2 -C 18 alkenyl, substituted or unsubstituted C 2 -C 18 alkynyl, substituted or unsubstituted aryl, a protecting group and —C(═O)R′ wherein R′ is selected from hydrogen, OH, NO 2 , NH 2 , SH, CN, halogen, C 1 -C 6 alkyl, alkenyl, alkynyl, aryl, aralkyl, and heterocyclic.