Remarkable Ligand Effect on Rh-Catalyzed C-H-Active [3 + 2] Annulation of Ketimines and Alkynes.

Externally added ligands were first found to have a significant impact on the Rh-catalyzed C-H-active [3 + 2] annulation of ketimines and alkynes. Olefin ligands have shown remarkable promotion effect for this reaction. The olefin promoted the reaction by increasing both the turnover rate and conversion of [Cp*RhCl2]2 in the formation of rhodacycle in the C-H activation step.