A facile one-pot ultrasound-assisted green synthesis of tetrahydrobenzo[b]pyrans catalyzed by gold nanoparticles supported on thiol-functionalized reduced graphene oxide

A convenient one-pot protocol was explored for the preparation of tetrahydrobenzo[b]pyrans. This reaction was carried out through a three-component condensation reaction of malononitrile, dimedone and aldehyde in the presence of gold nanoparticles on thiol-functionalized reduced graphene oxide as a catalyst in water under ultrasound irradiation. The pure products were obtained in high yields and short reaction times. Also, this catalyst can be easily separated from the reaction and recycled six times without activity loss.