Total synthesis of quercetin 3-sophorotrioside

5,7-Dihydroxy-3-[beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranosyl]-2-(3,4-dihydroxy- phenyl)-4H-1-benzopyran-4-one (quercetin 3-sophorotrioside), a flavonol triglycoside, isolated from Pisum sativurn shoots and showing protective effects on liver injury induced by chemicals, was synthesized for the first time. The target compound was successfully synthesized in eight linear steps and in 39% overall yield through a combination of phasetransfer-catalyzed (PTC) quercetin C-3 glycosylation and silver triflate (AgOTf) promoted carbohydrate chain elongation using both sugar bromide and trichloroacetimidate donors.