A neighboring group participation strategy: direct and highly diastereoselective synthesis of 2-substituted and 2,2-bisubstituted perhydrofuro[2,3-b]pyran derivatives

Abstract

Treatment of methyl 2-C-formylmethyl-2-deoxy-β-D-glucopyranoside (5) or methyl 2-C-acetylmethyl-2-deoxy-β-D-glucopyranoside (1) with H₂SO₄–HOAc–Ac₂O gave 2-acetoxyl-4,5-bis(benzyloxy)-6-[(benzyloxy)methyl]hexahydrofuro[2,3-b]pyran (6) and acetyl 2-C-acetylmethyl-2-deoxy-α-D-glucopyranoside (7) respectively, which were further reacted with nucleophiles in the presence of TMSOTf and offered a series of 2-substituted and 2,2-disubstituted perhydrofuro[2,3-b]pyran derivatives in high yield with excellent diastereoselectivity.