Aliphatic and Aromatic Intramolecular C−H Activation on Cp*Ir(NHC) Complexes

Facile intramolecular aliphatic and aromatic C−H activations have been observed for a series of complexes based on the “Cp*Ir(NHC)” fragment (NHC = 1-diphenylmethyl-3-methylimidazol-2-ylidene, 1-tert-butyl-3-methylimidazol-2-ylidene, 1-benzyl-3-tert-butylimidazol-2-ylidene, and 1-benzyl-3-isopropylimidazol-2-ylidene). We have performed a series of experiments for elucidating the factors that determine the aromatic or aliphatic C−H activations that occur. In the cases where both aliphatic and aromatic C−H activations are possible, steric factors govern the selectivity of the reaction.