Generalized Chemoselective Transfer Hydrogenation/Hydrodeuteration

A generalized, simple and efficient transfer hydrogenation of unsaturated bonds has been developed using HBP in and various proton reagents as hydrogen sources. The substrates, including alkenes, alkynes, aromatic heterocycles, aldehydes, ketones, imines, azo, nitro, epoxy and nitrile compounds, are all applied to this catalytic system. Various groups, which cannot survive under the Pd/C/H-2 combination, are tolerated. The activity of the reactants was studied and the trends are as follows:styrene>diphenylmethanimine>benzaldehyde>azobenzene>nitrobenzene>quinoline>acetophenone>benzonitrile. Substrates bearing two or more different unsaturated bonds were also investigated and transfer hydrogenation occurred with excellent chemoselectivity. Nano-palladium catalystin situgenerated from Pd(OAc)(2) and HBP in extremely improved the TH efficiency. Furthermore, chemoselective anti-Markovnikov hydrodeuteration of terminal aromatic olefins was achieved using D2O and HBP in via in situ HD generation and discrimination.