Copper-catalyzed radical reactions of 2-azido-N-arylacrylamides with 1-(trifluoromethyl)-1,2-benziodoxole and 1-azidyl-1,2-benziodoxole.

The reactions of 2-azido-N-arylacrylamides with trifluoromethyl radicals and azidyl radicals were investigated by using Togni's reagent and Zhdankin's reagent as the source of these radicals. Under the catalysis of CuI, Togni's reagent was firstly converted into the trifluoromethyl radical, which then reacted with 2-azido-N-arylacrylamides to afford the corresponding α-(arylaminocarbonyl)iminyl radicals. The cyclization of the iminyl radicals delivered quinoxalin-2(1H)-one products in moderate yields. A similar reaction took place between 2-azido-N-arylacrylamides and the azidyl radical. In the latter cases, the reaction produced 3-azidomethyl and 3-cyano-subsituted quinoxalin-2(1H)-ones. This study not only helps elucidate the factors influencing the cyclization of α-(arylaminocarbonyl)iminyl radicals, but also provides a new approach towards quinoxalin-2-ones.