Transfer hydrogenation of nitrogen heterocycles using a recyclable rhodium catalyst immobilized on bipyridine-periodic mesoporous organosilica

Transfer hydrogenation of unsaturated nitrogen heterocycles using a rhodium catalyst immobilized on bipyridine-periodic mesoporous organosilica (BPy-PMO) is described. The immobilized catalyst was prepared by mixing [Cp*RhCl2](2) (Cp* = eta(5)-C5Me5) with BPy-PMO powder in DMF at 60 degrees C and characterized by nitrogen adsorption measurements, solid-state NMR spectroscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, and transmission electron microscopy. In the presence of the catalyst, a wide variety of unsaturated nitrogen heterocycles underwent transfer hydrogenation to afford the corresponding products in good yields. The immobilized catalyst could be readily recovered by centrifugation and reused several times in the transfer hydrogenation process.