Preparation of tagged glucose as a key intermediate in the synthesis of branched oligosaccharides

The synthesis of pennogenin 3-O-β-D-glucopyranosyl-(1 → 3)-[α-L-rhamnopyranosyl-(1 → 2)]-β-D-glucopyranoside

Pennogenin 3-O-β-D-glucopyranosyl-(1 → 3)-[α-L-rhamnopyranosyl-(1 → 2)]-β-D-glucopyranoside, a monodesmosidic saponin isolated from Paris polyphylla Smith var. yunnanensis with promised antitumor activities, was firstly synthesized from glucoside thiol via nine steps and with 27% overall yield.