One-Pot Synthesis of Lewis X Oligosaccharide Derivatives Using “Armed-Disarmed” Coupling Method¹

1. Dedicated to the memory of Professor Akira Hasegawa.

Abstract

A stereocontrolled synthesis of Le^x oligosaccharide derivatives using a facile one-pot, two-step glycosylation based on the “Armed-Disarmed” concept are described. The first coupling of phenyl O-(2,6-di-O-benzoyl-3,4-O-isopropylidene-β-D-galacto-pyranosyl)-(1→4)-2,6-di-O-benzoyl-1-thio-β-D-glucopyranoside (2) with phenyl 2,3,4-tri-O-benzyl-1-thio-β-L-fucopyranoside (3) using N-iodosuccinimide (NIS)-trifluoromethanesulfonic acid (TfOH) gave the trisaccharide (8) which was subjected to the second condensation without purification with several acceptors such as ethyl 2,4,6-tri-O-benzyl-β-D-galactopyranoside (4), ethyl 2,6-di-O-benzoyl-β-D-galactopyranoside (5), ethyl O-(2,6-di-O-benzyl-β-D-galactopyranosyl)-(1→4)-2,3,6-tri-O-benzyl-β-D-glucopyranoside (6), and ethyl O-(2,6-di-O-benzoyl-β-D-galactopyranosyl)-(1→4)-2,3,6-tri-O-benzyl-β-D-glucopyranoside (7), to afford the desired Le^x tetra- and pentasaccharides in good yields, respectively.

1. Dedicated to the memory of Professor Akira Hasegawa.

Notes

1. Dedicated to the memory of Professor Akira Hasegawa.

Dedicated to the memory of Professor Akira Hasegawa