Ultrasound Promoted Synthesis of Benzo[a]pyrano-[2,3-c]phenazines Using Multisulfonic Acid Hyperbranched Polyglycerol Functionalized Graphene Oxide as a Novel and Reusable Catalyst

Abstract

A green and rapid sonochemical research to preparation of the benzo[a]- pyrano[2,3-c]phenazines was carried out through a four-component reaction of 2-hydroxynaphthalene-1,4-dione, o-phenylenediamine, aldehydes, and malononitrile by using multisulfonic acid hyperbranched polyglycerol modified graphene oxide as an effective and recyclable catalyst. This procedure has a number of advantages such as: excellent yields, short reaction times and green conditions. In addition, the catalyst could be recovered easily and reused several times without any considerable loss of its catalytic activity.