Ketone Hydrosilylation with Sugar Silanes Followed by Intramolecular Aglycone Delivery: An Orthogonal Glycosylation Strategy

摘要

Many classes of biomolecules derive their biological activity from the synergistic effects of carbohydrate and noncarbohy-drate (aglycone) functionalities.From the standpoint of chemical synthesis, the assembly of the aglycone and attachment of a carbohydrate (glycosylation) are viewed as distinct operations. As a result, the independent synthesis of a suitably protected aglycone and a suitably protected carbohydrate is typically followed by a separate sequence involving Lewis acid activation of the anomeric substituent on the sugar and assembly of the O-glycoside bond through the addition of an aglycone bearing a hydroxy group.The powerful glycal-oxidation method similarly involves the addition of a hydroxy nucleophile to the electrophilic anomeric position.