Preparation of Dihydronaphthofurans from α-Hydroxyl Ketones via a One-Pot Multicomponent Reaction Based on Heyns Rearrangement.

Polysubstituted 1,2-dihydronaphthofurans were efficiently obtained in high yields and good diastereoselectivities with readily available substrates. The reaction proceeds smoothly via a series of tandem reactions, including Heyns rearrangement, oxidation, Friedel-Crafts reaction, and cyclization. The high stereoselectivity of the reaction is ascribed to the activation of the imine via an intramolecular hydrogen bond. Air is directly used as the oxidation medium, which makes the reaction safe and easy to perform. Moreover, the reaction features multiple components, which ensures the diversity of products.