Cinchona-Derived Picolinamides: Effective Organocatalysts for Stereoselective Imine Hydrosilylation
作者:Pedro C. Barrulas、Andrea Genoni、Maurizio Benaglia、Anthony J. Burke
DOI:10.1002/ejoc.201403180
日期:2014.11
Picolinamide–cinchona organocatalysts for the successful enantioselective reduction of ketomines were developed. For the first time, a new type of chiral Lewis base, a cationic species, is reported to efficiently organocatalyze the addition of trichlorosilane to imines. Excellent yields with good to high enantioselectivities (up to 91 %) were obtained in the reduction of differently substituted substrates
The first enantioselective Bronsted acidcatalyzedreduction of imines has been developed. This new organocatalytic transfer hydrogenation of ketimines with Hantzsch dihydropyridine as the hydrogen source offers a mild method to various chiral amines with high enantioselectivity. The stereochemistry of the chiral amines can be rationalized by a stereochemical model derived from an X-ray crystal structure