Intramolecular Glycosidation by Click Reaction Mediated Spacer Generation Followed by Spacer Cleavage

Abstract

Abstract 2‐ O ‐Propargyl‐substituted glycosyl donors and O ‐(2‐azidobenzyl)‐substituted acceptors having a vicinal hydroxy group readily underwent the click reaction. Intramolecular glycosidation with N ‐iodosuccinimide/trifluoromethansulfonic acid as the activating system afforded β‐(1–3)‐ and α‐(1–2)‐linked disaccharides as part of 14‐membered macrocycles. Descriptors for these reactions are proposed that consider the donor and acceptor attachment sites and the stereochemistry of the functional groups. Investigation of the influence of 2‐ O ‐linked 1‐aryl‐1,2,3‐triazol‐4‐ylmethyl groups, as contained in the spacer, on the anomeric selectivity exhibited no anchimeric assistance. In addition, it was shown that the spacer group can be readily cleaved under Birch reduction conditions.