Acid-Catalyzed E-Ring Expansion and Isomerization of 3-Acetylbetulin: Synthesis of Cytotoxic Anhydrobetulin Saponins

作者：Thibeault Dominic; Legault Jean; Gauthier Charles; Lavoie Serge; Bouchard Jimmy; Pichette Andre^*

来源：Synthetic Communications, 2010, 40(2): 213-221.

DOI：10.1080/00397910902962886

• Acid-catalyzed isomerization
• anhydrobetulin saponins
• betulin
• cytotoxicity
• E-ring expansion
• triterpenoids

22(1728)abeo-Lupene derivatives 5a and 6a were obtained after the acid-catalyzed E-ring expansion of 3-acetylbetulin (1a). Glycosylation of these dehydrated triterpenoids using Schmidt's trichloroacetimidate sugar donors in the presence of trimethylsilyl trifluoromethanesulfonate (TMSOTf) provided the new anhydrobetulin saponins 7b-7e in which the terminal olefin C-20(29) isomerizes to form a C-19 tetrasubstituted alkene. The preliminary cytotoxic evaluation revealed that saponins 7b-7d exhibited a moderate cytotoxic activity against A549, DLD-1, and WS1 human cell lines with IC50 ranging from 22 to 49M.

• 出版日期2010