We explored the Pd-catalyzed reductions of imines using polymethylhydrosiloxane (PMHS) in the presence of aqueous KF. This methodology developed by our group facilitates the reduction of nitrogen-containing functional groups under mild conditions and short reactions times. To the best of our knowledge, there are no prior reports of imine reductions using Pd/PMHS/KF. After optimization of the reaction conditions with respect to the PMHS and KF concentrations, a screening of palladium salts was conducted. This screening proved that Pd(OAc)2 is the most efficient catalyst for these reductions.Chemoselective reductions of aromatic imines were achieved in the presence of nitriles, nitro, fluoride, and chloride substituents. On the other hand ketones, double bonds and bromide did not survive under these conditions and gave a complex mixture of products.The addition of PMHS to a Pd(OAc)2 solution result in the formation of polysiloxane encapsulated Pd-nanoparticles, and we were able to confirm the existence of these nanoparticles using transmission electron microscopy (TEM). The crucial role of KF was confirmed on these studies; without addition of KF agglomeration of the Pd-nanoparticles was observed.
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