One??Pot Synthesis of Polyfunctionalized 4H??Chromenes and Dihydrocoumarins Based on Copper (II) Bromide??Catalyzed C C Coupling of Benzylic Alcohols with …
Abstract The synthesis of polyfunctionalized 4H-chromenes 3 and dihydrocoumarins 4 has been developed from the same substrates. Catalyzed by copper (II) bromide (0.3 equiv.), the reactions of the easily available ketene dithioacetals 1 with 2-(hydroxymethyl) phenols 2 lead to 4H-chromenes 3 in high to excellent yields in dichloromethane solvent, whereas, 3, 4- trans-disubstituted dihydrocoumarins 4 are obtained in high yields with high ...