An improved synthesis of the saponin, polyphyllin D

Abstract Polyphyllin D, namely diosgenyl α- l -rhamnopyranosyl-(1→2)-[(α- l -arabinofuranosyl)-(1→4)]-β- d -glucopyranoside, was synthesized from diosgenyl-β- d -glucopyranoside in four steps and in 30% overall yield, taking advantage of regioselective pivaloylation and α- l -rhamnopyranosylation reactions.