Heterogeneous Iridium-Catalyzed Carbene N–H Bond Insertion with α-Alkyl Diazo Esters

A heterogeneous iridium single-atom site catalyst (Ir-SA) was synthesized and investigated in catalyzing the carbene insertion reaction with challenging α-alkyl diazo ester substrates. With only 0.23 mol % catalyst loading, our Ir-SA demonstrated remarkable performance in heterogeneous carbene N–H bond insertion reactions involving various (hetero) aryl amines coupled with α-alkyl diazo esters. Notably, in the case of using a chiral diamino substrate with two reactive sites, Ir-SA exhibited high selectivity toward single carbene N–H insertion, leading to the generation of a class of unsymmetric chiral diamino ligands. Further mechanism study revealed that the lower activation barrier associated with the single N–H bond insertion step, as compared to either β-hydride elimination or downstream dual N–H bond insertion, accounted for the remarkable selectivity observed in this carbene insertion reaction catalyzed by Ir-SA.