Xiuwen Han

Synthesis of three diosgenyl saponins: dioscin, polyphyllin D, and balanitin 7

Dioscin, polyphyllin D, and balanitin 7, which belong to a group of structurally similar diosgenyl saponins with promising bioactivities, were synthesized by stepwise glycosylation.

An improved synthesis of the saponin, polyphyllin D

Polyphyllin D, namely diosgenyl alpha-L-rhamnopyranosyl-(1 --> 2)- [(alpha-L-arabinofuranosyl)-(1 --> 4)]-[beta-D-glucopyranoside, was synthesized from diosgenyl-beta-D-glucopyranoside in four steps and in 30% overall yield, taking advantage of regioselective pivaloylation and alpha-L-rhamnopyranosylation reactions.

Synthesis of a typical N-acetylglucosamine-containing saponin, oleanolic acid 3-yl α-l-arabinopyranosyl-(1→2)-α-l-arabinopyranosyl-(1→6)-2-acetamido-2-deoxy-β-d-glucopyranoside

Abstract Oleanolic acid 3-yl α- l -arabinopyranosyl-(1→2)-α- l -arabinopyranosyl-(1→6)-2-acetamido-2-deoxy-β- d -glucopyranoside, a cytotoxic saponin isolated from Acacia tenuifolia and Albizia subdimidiata with a typical structure of the N -acetylglucosamine-containing plant saponins, was synthesized. The synthesis adopted a stepwise glycosylation fashion employing glycosyl trifluoroacetimidates 5 and 9 and thioglycoside 12 as donors.

Synthesis of quercetin 3-O-(2′′-galloyl)-α-l-arabinopyranoside

Abstract Quercetin 3- O -(2′′-galloyl)-α- l -arabinopyranoside, a plant flavonol glycoside showing HIV-1 integrase inhibition, antibacterial, and antioxidant activities, was synthesized, with the glycosylation of the flavonol 3-OH being explored.

Synthesis of a group of diosgenyl saponins by a one-pot sequential glycosylation

Abstract A group of natural diosgenyl saponins was synthesized in a highly efficient manner employing the ‘one-pot sequential glycosylation’ protocol with the combined use of glycosyl trichloroacetimidates and thioglycosides.

Lipase-catalyzed regioselective acylation of diosgenyl saponins

Diosgenyl saponins were regio selectively acylated by Novozyme 435 with vinyl esters as acylating agents in THF to afford the corresponding mono- or diacyl diosgenyl saponins

Synthesis of a group of diosgenyl saponins with combined use of glycosyl trichloroacetimidate and thioglycoside donors

With the combined use of glycosyl trichloroacetimidates and thioglycosides, a group of natural diosgenyl saponins (1–6) are efficiently synthesized, in either a stepwise or a ‘one-pot’ manner. The trichloroacetimidate is employed as an efficient temporary hydroxy protecting group in glycosylation with the glycosyl trichloroacetimidate. The intermolecular alkylthio-group transfer is demonstrated to be a common side-reaction during glycosylation with thioglycosides.