Palladium-catalyzed direct phosphonation of azoles with dialkyl phosphites

The first Pd-catalyzed direct phosphonation of azoles with dialkyl phosphites has been achieved without addition of base or acid. This method involves the oxidative cleavage of C-H and P(O)-H bonds and represents an atom-efficiency alternative to the classical phosphonation of Ar-X. A Pd-II/Pd-IV mechanism has been studied and proposed.