An ecofriendly approach to the synthesis of 2-imino- and 2-oxo-3-phenylsulfonyl-2H-chromenes

An efficient synthesis for 2-imino-3-phenylsulfonyl-2H-chromenes was developed from the Knoevenagel condensation of (phenylsulfonyl)acetonitrile and salicylaldehydes in aqueous sodium carbonate solution, at room temperature. Hydrolysis in aqueous HCl, at 80 °C, led to the formation of the corresponding 2-oxo-3-phenylsulfonyl-2H-chromenes, also isolated in excellent yields.