Ligand-Free Iron-Catalyzed C–F Amination of Diarylamines: A One-Pot Regioselective Synthesis of Diaryl Dihydrophenazines

A one-pot synthesis of various 5,10-diaryl-5,10-dihydrophenazines (DADHPs) from diarylamines has been achieved by using an iron-catalyzed C–F amination. Homodimerization of magnesium diarylamides, followed by defluorinative intramolecular cyclization (double ortho C–F amination) in the presence of catalytic FeCl₂ and stoichiometric 1,2-dibromoethane, affords the corresponding DADHPs with complete regiocontrol. The unique high reactivity of fluorine over other halogens indicates that amination proceeds via an S_NAr mechanism facilitated by iron.