One-pot synthesis of tetrahydrobenzo[b]pyran derivatives in aqueous solution catalyzed by [DHC3dabco][BF4] under ultrasonic assistance

A basic ionic liquid [DHC3dabco][BF4] based on DABCO was synthesized and used for the preparation of tetrahydrobenzo[b]pyran derivatives. This ionic liquid was used as a catalyst, and aldehydes, malononitrile and 5,5-dimethyl-1,3-cyclohexanedione were used as raw materials. The reaction was performed in aqueous solution under ultrasonic assistance at room temperature. The synthesis process is a mild, simple, time-efficient one with high yield. Based on the simple active methylene compounds, the reaction performance of other active methylene compounds was also discussed. ©, 2015, Zhejiang University. All right reserved.