Green Synthesis of Naphthyloyl Biscoumarins, Naphthyloyl Pyranocoumarins, and Naphthyloyl Amidocoumarins based on Naphthyl Glyoxals Catalyzed by ZnO Nanowires

Abstract

A series of synthetic methods for synthesis of organic compounds containing naphthyloyl group have been explored via one-pot reactions catalyzed by zinc oxide nanowires (ZnO NWs). In the first reaction, new biscoumarins have been synthesized through the reaction of naphthyl glyoxals with 4-hydroxycoumarin. In the next one, new pyranocoumarins have been obtained from the one-pot, three component reaction of naphthyl glyoxals with malononitrile and 4-hydroxycoumarin. In the final study, the naphthyl glyoxals were also employed for the synthesis of new amidocoumarins in a three-component reaction with 4-hydroxycoumarin and benzamide. It is noteworthy to mention that the green chemistry principles have been considered in all strategies. The advantages of the present methods are good product yield in a short reaction time, avoidance of toxic and expensive organic solvents, use of safe and recoverable catalyst, and simple operation.