Synthesis of 2,7-Disubstituted 5,10-Diaryl-5,10-dihydrophenazines via Iron-Catalyzed Intramolecular Ring-Closing C–H Amination

A novel iron-catalyzed intramolecular ring-closing C–H amination reaction of o-phenylenediamines was developed, affording the corresponding 2,7-disubstituted 5,10-diaryl-5,10-dihydrophenazines in acceptable yields. The reaction proceeded via the in-situ generation of the magnesium amides of the starting secondary amines in the presence of a catalytic amount of an iron salt and a stoichiometric amount of 1,2-dibromoethane as the terminal oxidant. The substituted dihydrophenazine derivatives can potentially be used as hole-injection materials in organic electroluminescence (OEL) devices and also offer scaffolds for further synthetic elaborations of OEL materials.