Palladium-catalyzed direct regioselective ortho-phosphonation of aromatic azo compounds with dialkyl phosphites.

An efficient palladium-catalyzed regioselective C-P bond formation of azo compounds through C-H bond functionalization using dialkyl phosphites as phosphorus source under mild conditions was developed. A series of both symmetrical and unsymmetrical azoarenes were successfully phosphonylated through this procedure with tolerance of a broad range of functional groups.