Nickel-Catalyzed Defluorophosphonylation of Aryl Fluorides.

A Ni-catalyzed cross-coupling reaction between aryl fluorides and dialkyl phosphonates [HP(O)(OR)] (R = secondary alkyl groups) in the presence of potassium -butoxide as a base is reported. The reaction converted various aryl fluorides into the corresponding aryl phosphonates even when electron-donating substituents were present on the aromatic ring. The combined experimental and computational studies suggested Ni-K cooperative action of a Ni(0) complex chelated with a strongly electron-donating ion-bridged dimeric phosphite ligand system [P(OR)OK] that facilitates turnover-limiting C-F bond oxidative addition of aryl fluorides.

Phosphinylation of Non-activated Aryl Fluorides through Nucleophilic Aromatic Substitution at the Boundary of Concerted and Stepwise Mechanisms.

Non-activated aryl fluorides reacted with potassium diorganophosphinites through a nucleophilic aromatic substitution (S Ar) reaction. Remarkably, both electron-neutral and electron-rich aryl fluorides participated in the reaction with substantially stabilized anionic P nucleophiles to form the corresponding tertiary phosphine oxides. Quantum chemical calculations suggested a nucleophile-dependent mechanism that involves both concerted and stepwise S Ar reaction pathways.