Iron-Catalyzed Reductive Coupling of Nitroarenes with Olefins: Intermediate of Iron–Nitroso Complex

Using a single half-sandwich iron­(II) compound, Cp*Fe­(1,2-Ph2PC6H4S)­(NCMe) (Cp*– = C5Me5–, 1) as a catalyst, reductive coupling of nitroarenes with olefins has been achieved by a well-defined iron­(II)/(EtO)3SiH system. Through either inter- or intramolecular reductive coupling, various branched amines and indole derivatives have been directly synthesized in one-pot. Mechanistic studies showed that the catalysis is initiated by activation of nitroarenes by the iron­(II) catalyst with silane, generating iron–nitrosoarene intermediate for the C–N bond coupling.