Access to Diosgenyl Glycoconjugates via Gold(I)-Catalyzed Etherification of Diosgen-3-yl ortho-Hexynylbenzoate.

An efficient protocol for the synthesis of diverse diosgen-3-yl glycoconjugates, a class of novel synthetic analogs of natural saponins of biological significance, has been developed. The method relies on gold(I)-catalyzed etherification of diosgen-3-yl ortho-hexynylbenzoate with stoichiometric sugar alcohols to afford the corresponding glycoconjugates in 38%–99% yields. The reaction involves the preferential attack of hydroxyl groups to the C3 position of homoallylic carbocation intermediate and displays a broad substrate scope and a good functional group tolerance.