Total Synthesis of Starfish Cyclic Steroid Glycosides. Part 2, Model Synthesis via Intramolecular Etherification

Abstract

Comprehensive SummarySepositoside A (1) is a prototypical cyclic steroid glycoside bearing a hybrid 16‐membered ring composed of the steroid skeleton and a 1,2‐trans‐linked trisaccharide. Herein, we report an expedient access toward two simplified analogues, in which the strained 16‐membered ring is constructed via Au(I)‐catalyzed intramolecular addition of alcohol to epoxide. A similar macroetherification in relevant steroid trisaccharides has been intensively examined, however, failed to furnish the macrocyclic skeleton of Sepositoside A.