Effective and convenient synthesis of 2-amino-4H-chromenes promoted by melamine as a recyclable organocatalyst

This study focused on the applicability of melamine as a cheap and efficient organocatalyst in the acceleration of the synthesis of 4-aryl-4H-chromenes derivatives. Under the selected conditions, a wide range of aldehydes readily underwent condensation with activated phenols and malononitrile to afford the high to excellent yields. Also, organocatalyst was used for the synthesis of 2-amino-5,10-dioxo-5,10-dihydro-4H benzo[g]chromenes by the reaction of aromatic aldehydes, malononitrile and 2-hydroxynaphthalene-1,4-dione in refluxing H2O:EtOH. This method provides several advantages such as convenient work-up, mild reaction conditions, use of an inexpensive and readily available catalyst, short reaction times, high yields of the products and reusability of the catalyst.