Synthesis of a Blocked Tetrasaccharide Related to the Repeating Unit of the Antigen from Shigella dysenteriae Type 9 in the Form of Its Methyl (R)‐Pyruvate Ester and 2‐(Trimethylsilyl)Ethyl Glycoside

Abstract

Starting from d‐mannose, d‐galactose and d‐glucosamine hydrochloride, two disaccharide blocks were synthesized. Schmidt's inverse addition technique of trichloroacetimidate was utilized for the construction of a disaccharide with a β‐mannosidic linkage in good yield. The other disaccharide had a methyl 4,6‐(R)‐pyruvate ester. The two disaccharides in the appropriate form were then allowed to react in the presence of N‐iodosuccinimide (NIS) and trifluoromethanesulfonic acid (TfOH) to give the desired tetrasaccharide derivative, 2‐(trimethylsilyl)ethyl 2‐acetamido‐3,4,6‐tri‐O‐benzoyl‐2‐deoxy‐β‐d‐glucopyranosyl‐(1→3)‐2‐O‐benzoyl‐4,6‐O‐[(R)‐1‐methoxycarbonylethylidene]‐β‐d‐galactopyranosyl‐(l→4)‐2,3,6‐tri‐O‐benzyl‐β‐d‐mannopyranosyl‐(1→4)‐2,6‐di‐O‐benzyl‐3‐O‐(4‐methoxybenzyl)‐β‐d‐galactopyranoside.

^†This paper is dedicated to Professor Gérard Descotes on the occasion of his 70th birthday.

Keywords:

• Synthesis
• Tetrasaccharide derivative
• Shigella dysenteriae type 9

Acknowledgments

Financial support from the Department of Science and Technology, New Delhi, India (Project No. SP/S1/G14/95) is thankfully acknowledged.

Notes

^†This paper is dedicated to Professor Gérard Descotes on the occasion of his 70th birthday.