Copper-Catalyzed One-Pot Synthesis of 2-Arylthiochromenones: An in Situ Recycle of Waste Byproduct as Useful Reagent.

Copper-catalyzed one-pot synthesis of various 2-arylthiochromenones is developed using xanthate as an odorless sulfur source from easily acquirable 2'-halochalcones. This methodology demonstrates that the cross-coupled product thiochromanone synthesized from 2'-halochalcones (upstream reaction) is oxidized to thiochromenone (downstream reaction) in the same pot using waste byproduct (KI) of the first step as powerful oxidant molecular iodine (I2). This one-pot synthesis has been further extended for the synthesis of 3,3'-methylenebisthioflavone using dimethyl sulfoxide (DMSO) as solvent and methylene source.