Efficient synthesis of lupane-type saponins via gold(I)-catalyzed glycosylation with glycosyl ortho-alkynylbenzoates as donors

Abstract

Glycosylation of the acid labile betulin and betulinic acid derivatives was achieved with glycosyl ortho-hexynylbenzoates as donors under the catalysis of PPh(3)AuNTf(2); this enabled the efficient synthesis of lupane-type saponins, as exemplified by the total synthesis of the proposed betulinic acid trisaccharide from Bersama engleriana.