ZnCl2-catalyzed Ferrier reaction; synthesis of 2,3-unsaturated 1-O-glucopyranosides of allylic, benzylic and tertiary alcohols

Tertiary, allylic and benzylic alcohols react with 3,4,6-tri-O-acetyl-d-glucal in dichloromethane at 25°C in the presence of ZnCl2 to afford the corresponding 2,3-unsaturated-1-O-glucopyranoside acetates in 65–91% yields, with selective formation of the α-anomer.