Enantioselective Catalytic Reduction of Ketoimines with Trichlorosilane Promoted by Readily Available Chiral Lewis Bases

The straightforward synthesis of a series of enantiomerically pure Lewis basic amides by simple condensation of commercially available enantiopure diamines with picolinic acid is reported. These compounds were shown to promote the enantioselective reduction of ketoimines with trichlorosilane. Working with the model substrate N-phenyl benzophenone imine, the new organocatalysts led to the formation of the corresponding amine, with excellent chemical efficiency (up to 99% chemical yield) and good stereoselectivity (up to 73% ee). Up to 83% of enantioselectivity was reached in the reduction of differently substituted imines. Chirality 21:233-238, 2009. (c) 2008 Wiley-Liss, Inc.