Iron-Catalyzed Allylic Arylation of Olefins via C(sp3)–H Activation under Mild Conditions

An aryl Grignard reagent in the presence of mesityl iodide converts an allylic C–H bond of a cycloalkene or an allylbenzene derivative into a C–C bond in the presence of a catalytic amount of Fe(acac)3 and a diphosphine ligand at 0 °C. The stereo- and regioselectivity of the reaction, together with deuterium labeling experiments, suggest that C–H bond activation is the slow step in the catalytic cycle preceding the formation of an allyliron intermediate.