An expedient synthesis of benzyl 2,3,4-tri-O-benzyl-β-d-glucopyranoside and benzyl 2,3,4-tri-O-benzyl-β-d-mannopyranoside

An efficient three-step synthesis of benzyl 2,3,4-tri-O-benzyl-β-d-glucopyranoside, a widely used building block in carbohydrate chemistry, is described. The key step is the selective debenzylation–acetylation of perbenzylated β-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-β-d-mannopyranoside.