Synthesis of α-carbolines by copper-catalyzed radical cyclization β-(3-indolyl) ketone O-pentafluorobenzoyloximes

Radical cyclization of beta-(3-indolyl) ketone O-pentafluorobenzoyloximes proceeds by the treatment with a catalytic amount of copper powder in 1,2-dichloroethane to generate 3,4-dihydro-alpha-carbolines, which are oxidized to alpha-carbolines with chloranil.