Synthesis of triarylphosphines from arylammonium salts via one-pot transition-metal-free C–P coupling

A nucleophilic aromatic substitution (S_NAr) reaction that allowed transition-metal-free C–P bond construction via C–N bond cleavage was developed. The coupling between aryltrimethylammonium salts and secondary phosphines from the in situ reduction of diarylphosphine oxides led to the formation of diverse triarylphosphines with various functional groups. This one-pot process was not only a pertinent S_NAr precedent but also a favorable transition-metal-free alternative for C–P coupling.