Room Temperature Na2CO3-Catalysed One-pot Reaction of Benzaldehydes, Malononitrile and Phloroglucinol in Water, a Simple Green Synthetic Route to Antibacterial 2-Amino-4H-Benzopyrans

A simple and green room temperature Na2CO3-catalysed three-component reaction of benzaldehydes, malononitrile and phloroglucinol in water to give 2-amino-4H-benzopyrans in 70-96% yields is described. The reaction was tolerated by electron-donating and electron-withdrawing substituents on the benzaldehydes. Operational simplicity, use of readily available and safe reagents, easy work-up and high yields are some of the positive attributes of this method. The prepared compounds showed very good to promising activities against both gram negative and gram positive bacteria with minimum inhibitory concentrations of 0.25 to 25.0 mg/ml as compared to that of ciproflaxin at 0.25 mg/ml.