Arene hydrogenation was greatly accelerated by a cooperative catalytic system that consisted of heterogeneous Rh-Pt nanoparticles and Lewis acids. Remarkably, particularly challenging substrates that contained strong electron-donating groups and sterically hindered substituents could be smoothly hydrogenated.
Employing two distinct catalysts in one reaction medium synergistically is a powerful strategy for activating less reactive substrates. Although the approach has been well-developed in homogeneous conditions, it remains challenging and rare in heterogeneous catalysis, especially under gas-liquid-solid multiphase reaction conditions. Here, we describe the development of cooperative and synergistic catalyst systems of heterogeneous Rh-Pt bimetallic nanoparticle catalysts, Rh-Pt/DMPSi-Al2O3, and Sc(OTf)3 in the liquid phase for the hydrogenation of arenes under very mild conditions. Dramatic rate acceleration was achieved with cooperative activation. Remarkably, more challenging substrates that contained strong electron-donating groups and sterically hindered substituents were smoothly hydrogenated. Mechanistic insights into the cooperative activation of an aromatic substrate by heterogeneous metal nanoparticles and a soluble Lewis acid was obtained by kinetic studies and by direct observation of 1H and 45Sc NMR spectra.Zum Volltext