Multicomponent reaction through cooperative trio catalysis incorporating enamine, Brønsted acid and metal Lewis acid catalysis: a concise route to access chromans.

An atom-economical multicomponent cascade reaction of salicylaldehydes, cyclohexanones and arylamines has been developed for the synthesis of three-ring fused chromans. This reaction was achieved through cooperative enamine-metal Lewis acid assisted Brønsted acid catalysis, furnishing the products in excellent yields with good diastereoselectivity.