Approaches to the efficient synthesis of N-glycosyl amides and triazoles

Abstract

The stereoselective and regiospecific synthesis of N-glycosides was accomplished using two powerful sets of reaction conditions. Modified Staudinger chemistry using bis(Diphenylphosphino)ethane as a phosphine in reaction with a B-glycosyl azide and acylating agent afforded B-glycosyl amides in good yields. Aglucuronic acid-derived acyl chloride was prepared and the Staudinger conditions were used to investigate the synthesis of oligomeric species. Several carbohydrate-derived alkynes were also prepared and reacted with glycosyl azides using Cu(I)-catalysis in order to form only 1,4-disubstituted-B-glycosyl-1,2,3-triazoles in good to high yields. These reactions conditions furnish N-glycosidic products that also maintain the stereochemistry of the B-glycosyl azide precursor. X-Ray crystallography was used to verify regiochemistry and stereochemistry. These conditions were also applied to the synthesis of oligomeric structures, as well as several divalent species that were built upon a diethynyl benzene core.