Efficient Hydrogenation of N-Heterocycles Catalyzed by NNP-Manganese(I) Pincer Complexes at Ambient Temperature.

Manganese-catalyzed hydrogenation reactions have aroused widespread interest in recent years. Among the catalytic systems described, especially PNP- and NNP-Mn pincer catalysts have been reported for the hydrogenation of aldehydes, ketones, nitriles, aldimines and esters. Furthermore, NNP-Mn pincer compounds are efficient catalysts for the hydrogenolysis of less reactive amides, ureas, carbonates, and carbamates. Herein, the synthesis and application of specific imidazolylaminophosphine ligands and the corresponding Mn pincer complexes are described. These new catalysts have been characterized and studied by a combination of experimental and theoretical investigations, and their catalytic activities have been tested in several hydrogenation reactions with good to excellent performance. Especially, the reduction of N-heterocycles can be performed under very mild conditions.

Diastereoselective hydrogenation of arenes and pyridines using supported ruthenium nanoparticles under mild conditions.

A convenient and practical diastereoselective cis-hydrogenation of multi-substituted pyridines and arenes is reported. Applying a novel heterogeneous ruthenium catalyst, the corresponding piperidines and cyclohexanes are obtained in high yields (typically >80%) with a good functional group tolerance under mild conditions. The robust ruthenium supported catalyst is smoothly prepared and can be reused multiple times without activity loss.