An expedient synthesis of benzyl 2,3,4-tri-O-benzyl-beta-D-glucopyranoside and benzyl 2,3,4-tri-O-benzyl-beta-D-mannopyranoside.

An efficient three-step synthesis of benzyl 2,3,4-tri-O-benzyl-beta-D-glucopyranoside, a widely used building block in carbohydrate chemistry, is described. The key step is the selective debenzylation-acetylation of perbenzylated beta-glucose using ZnCl2-Ac2O-HOAc. This approach was also used to affect an efficient three-step synthesis of benzyl 2,3,4-tri-O-benzyl-beta-D-mannopyranoside.