Copper-Catalyzed Radical/Radical Csp3-H/P-H Cross-Coupling: α-Phosphorylation of Aryl Ketone O-Acetyloximes

The selective radical/radical cross-coupling of two different organic radicals is a great challenge due to the inherent activity of radicals. In this paper, a copper-catalyzed radical/radical Csp3H/PH cross-coupling has been developed. It provides a radical/radical cross-coupling in a selective manner. This work offers a simple way toward -ketophosphonates by oxidative coupling of aryl ketone o-acetyloximes with phosphine oxides using CuCl as catalyst and PCy3 as ligand in dioxane under N-2 atmosphere at 130 degrees C for 5h, and yields ranging from 47% to 86%. The preliminary mechanistic studies by electron paramagnetic resonance (EPR) showed that, 1)the reduction of ketone o-acetyloximes generates iminium radicals, which could isomerize to -sp(3)-carbon radical species; 2)phosphorus radicals were generated from the oxidation of phosphine oxides. Various aryl ketone o-acetyloximes and phosphine oxides were suitable for this transformation.