Ferrier Rearrangement of 1,2-Dihydropyrans with Organozinc Species in Toluene/n-Dibutyl Ether

Abstract

Herein, we report the catalyst-free addition of organozinc species to glycal derivatives and dihydropyrans in a toluene/n-dibutyl ether solvent mixture via a Ferrier rearrangement at room temperature. This methodology requires only a slight excess of the nucleophile and leads preferentially to the C-glycoside α-anomer. Various 1,2-dihydropyrans were assessed with a range of nucleophiles (aryl, alkynyl, alkyl) yielding the desired C-glycosides in good yield and diastereoselectivity up to 20:1.