Efficient One-Pot Synthesis of 2-Amino-4H-chromenes Catalyzed by Ferric Hydrogen Sulfate and Zr-Based Catalysts of FI

Fe(HSO4)(3) efficiently catalyzes the synthesis of 2-amino-4H-chromenes. The reactions proceed through a one-pot, three-component condensation of alpha- or beta-naphthol, aromatic aldehyde derivatives, and malonitrile in the presence of a catalytic amount of ferric hydrogen sulfate. Also, three-component condensation of resorcinol, malononitrile, and various aldehydes using the catalyst gave the corresponding 2-amino-4H-chromenes in good yields. The catalyst displayed high activity and recyclability without loss of its catalytic activity. Additionally, three Zr-based FI catalysts were applied for the one-pot synthesis of chromene derivatives. Although the chemical yield was not high, it is the first report of using such catalysts in the field.