A simple and eco-friendly approach for the synthesis of 2-imino and 2-oxo-2H-chromene-3-carboxamides

A series of new 2-imino-2H-chromene-3-carboxamides 5 were synthesized in excellent yield and high atom economy by the Knoevenagel condensation of salicylaldehyde derivatives 4 and N-substituted cyanoacetamides 3 using aqueous sodium carbonate or hydrogen carbonate solution, at room temperature. Treatment of compounds 5 with aqueous HCl led to the formation of the corresponding 2-oxochromenes 6.