Investigation of Steric and Electronic Features of 3‑Iminophosphine-Based Palladium Catalysts for Intermolecular Hydroamination

A series of (3-iminophosphine)­allylpalladium triflate complexes with systematic variation of both steric and electronic features was isolated and characterized. The ability of the complexes in this series to catalyze the regioselective hydroamination of 3-methyl-1,2-butadiene with aryl amines to form solely the kinetic product was probed by observing conversion to products via NMR spectroscopy. The previously unstudied 3-iminophosphine ligand composed of a di-tert-butyl phosphine, cyclobutene backbone, and tert-butyl imine provided the most active palladium hydroamination catalyst for this transformation known to date.