HMPA-Catalyzed Transfer Hydrogenation of 3-Carbonyl Pyridines and Other <em>N</em>-Heteroarenes with Trichlorosilane

Abstract

A method for the HMPA (hexamethylphosphoric triamide)-catalyzed metal-free transfer hydrogenation of pyridines has been developed. The functional group tolerance of the existing reaction conditions provides easy access to various piperidines with ester or ketone groups at the C-3 site. The suitability of this method for the reduction of other N-heteroarenes has also been demonstrated. Thirty-three examples of different substrates have been reduced to designed products with 45–96% yields.

Keywords

• HMPA
• transfer hydrogenation
• trichlorosilane
• pyridines