Glycerol and acetic acid assisted mild strategy for facile synthesis of 3-heteroarylcoumarins via three-component reaction

A feasible and inexpensive reaction system for synthesis of 3-benzoxazol-2-yl-chromen-2-one as a kind of 3-heteroarylcoumarins has been developed. Both acetic acid and glycerol are simple, cheap and common chemicals, the combination of them could smoothly accelerate the three-component one-pot reaction of salicylaldehyde, o -aminophenol and ethyl cyanoacetate to yield 3-heteroarylcoumarins. This process not only offers the products in good to excellent yields but also avoids the problems associated with catalyst cost, handling, safety and pollution. Compared with the literature, the reaction temperature successfully reduced to 80 °C. As an application, disperse yellow 232 was furnished with a satisfactory yield under optimum reaction conditions. In addition, all synthesized 3-heteroarylcoumarins were preliminary evaluated the inhibitory effect against human carboxylesterase 1. This protocol offers an expedient strategy for efficient synthesis of 3-heteroarylcoumarins that are widely present in biologically active compounds and fluorescent paints.