Synthesis of coumarin-3-ethyl formate under microwave irradiation without solvent

Six coumarin-3-ethyl formates were synthesized from substituted salicylaldehyde and diethyl monlonate under microwave irradiation without solvent.The structure of the title compounds were characterized by IR,1H NMR and 13C NMR.The optimum parameters of coumarin-3-ethyl formate were obtained by orthogonal test: microwave power 400 W,reaction time 6 min,ratio of aldehyde to diethyl monalate 1∶1.3 and piperizine 0.3 mL respectively.Under this optimized condition,the yield of the title compounds were 39.2%～85.9% with such advantages as short time,high yields and environmentally benign procedures compared with the traditional methods.