Basic Ionic Liquid Catalyzed Rapid Three-Component Synthesis of tetrahydrobenzo[b]pyran at Ambient Temperature

Abstract

An efficient and convenient approach for the synthesis of tetrahydrobenzo[b]pyran derivatives under mild condition using the task specific ionic liquid 1,8-diazabicyclo[5.4.0]-undec-7-en-8-ium acetate ([DBU][Ac])as an efficient catalyst is described. A wide range of aromatic aldehydes easily undergo condensation with malononitrile and 5,5-dimethylcyclohexane-1,3-dione (dimedone) to afford the desired products in excellent yields. Taking into account the environmental and economical considerations, the present protocol has the merits of environmentally benign procedure such as shorter reaction time, low cost, recycling of the catalyst and simple workup.