A tandem annulation with a [1,3]-hydride transfer as the key step leading to isochromans

Abstract

An unprecedented method that enables the direct coupling of an α-C–H bond in alcohols with 2-arylacetaldehydes through a [1,3]-hydride transfer ([1,3]-HT) of oxocarbenium ions catalyzed by a Lewis acid has been developed. The redox neutral preparation of the isochroman derivatives proceeds via a tandem condensation/[1,3]-HT/Friedel–Crafts sequence with moderate to good yields. Deuterium-labeling studies provide mechanistic insights and reveal that the redox functionalization proceeds via a [1,3]-HT.