Photodriven, TFA-promoted oxidative dehydrogenative coupling of quinoxalin-2(1H)-ones with 5-pyrazolones

A novel protocol of photodriven, TFA-mediated oxidative coupling of quinoxalin-2(1H)-ones with 5-pyrazolones to prepare 4-quinoxalinone-pyrazolones has been realized under air. A visible-light-catalyzed method was first employed to synthesize these derivatives and the reactions afforded the desired products moderate to excellent yields. This protocol can be applied to the efficient synthesis of quinoxalinone drug analogs. Mechanistic investigation suggested that a radical pathway exists and TFA plays an important role in the formation of the products.