ZnCl2-catalyzed three-component domino reactions for the synthesis of pyrano[3,2-c]quinolin-5(6H)-ones

The ZnCl2-catalyzed three-component synthesis of pyrano[3,2-c]quinolin-5(6H)-ones from the domino reactions of 4-hydroxy-1-methylquinolin-2(1H)-one, nitroketene N,S-methylacetal, and aromatic aldehydes in ethanol in good yields is described. This domino transformation leads to the formation of one ring by creation of two C-C bonds and one C-O bond in a single synthetic operation.