N-glycoside neoglycotrimers from 2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyl azide

2,3,4,6-Tetra-O-acetyl-beta-D-glucopyranosyl azide is available on large scale from D-glucose by means of a three-step sequence involving acetylation, activation as the glycosyl bromide, and stereospecific displacement with azide anion. The azide functionality then serves as a convenient anchor upon which to introduce new functionality, usually with retention of the beta-stereochemistry. Here we report the synthesis of an amide-linked N-glycosyl trimer, by employing a Staudinger-aza-Wittig process on the azide, as well as a hybrid N-glycosyl triazole-amide-linked trimer in which the sugars are separated by 1,2,3-triazole heterocycles. Both of these neoglycotrimers are isolated in good yield with high P-selectivity in each case. (c) 2006 Elsevier Ltd. All rights reserved.