De Novo Approach to 2-Deoxy-β-Glycosides: Asymmetric Syntheses of Digoxose and Digitoxin

摘要

A highly enantioselective and straightforward route to trisaccharide natural product digoxose and digitoxin has been developed. Key to this approach is the iterative application of the palladium-catalyzed glycosylation reaction, reductive 1,3-transposition, diastereoselective dihydroxylation and regioselective protection. The first total synthesis of natural product digoxose was accomplished in 19 total steps from achiral 2-acylfuran and the digitoxin was fashioned in 15 steps starting from digitoxigenin >2 and pyranone >8β. This flexible synthetic strategy also allows for the preparation of mono- and disaccharide analogues of digoxose and digitoxin.