After surveying the substrate scope of the three types of asymmetric arylative radical cross-coupling reactions, we initiated mechanistic investigations to gain some insight into the reaction. Treatment of the radical clock substrate 13 with oxime carbonate 2a and phenylboronic acid 3a under the standard reaction conditions afforded the ring-opening product 14 in 58% yield and 88% ee, which supported the intermediacy of a labile benzylic radical 13-A that is prone to ring-opening (Figure ).