Highly Selective Intramolecular Carbene Insertion into Primary C–H Bond of α-Diazoacetamides Mediated by a (p-Cymene)ruthenium(II) Carboxylate Complex

Complex [(p-cymene)­Ru­(η1-O2CCF3)2(OH2)] mediated transformation of α-diazoacetamides ArCH2N­(C­(CH3)3)­C­(O)­CHN2 to result in carbene insertion into the primary C–H bond exclusively, with the γ-lactam products being isolated in up to 98% yield. This unexpected reaction is striking in view of the presence of usually more reactive sites such as secondary C–H bonds in the substrates. DFT calculations based on proposed Ru-carbene species provide insight into this unique selectivity.