A new three-component coupling reaction of aryl glyoxal, malononitrile, and 4-hydroxy coumarin catalysed by recyclable TiO2 nanoparticles

Abstract

Aryl glyoxals reacted with malononitrile and 4-hydroxycoumarin in the presence of a catalytic amount of TiO2 nanoparticles to give a hitherto unknown family of pyranochromenes in up to 80% yield. This new three-component reaction yielded some novel pyrano[3,2-c]chromene-5-ones containing an aroyl substituent. Using a recyclable and safe catalyst along with a green solvent system made the process eco-friendly and economic.