Silica Tungstic Acid as a Recyclable Catalyst to Synthesis of Benzo[5,6]Chromeno[2,3-b]Quinolins under Green Conditions

Abstract

An impressive procedure for synthesis of benzo[5,6]chromeno[2,3-b]quinolin derivatives is described. First, benzo[f]chromene-2-carbonitriles are synthesized from the reaction of aryl aldehydes, malononitrile, and β-naphthol in the presence of silica sodium carbonate as a heterogeneous basic catalyst. Next, the prepared benzo[f]chromene-2-carbonitriles are reacted with cyclohexanone using 10 mol% of silica tungstic acid as an efficient and recyclable catalyst to produce known and unknown benzo[5,6]chromeno[2,3-b]quinolin derivatives under solvent-free conditions in good to excellent yields.