Highly Enantioselective and Regioselective Carbonyl Reduction of Cyclic α,β-Unsaturated Ketones Using TarB-NO<sub>2</sub> and Sodium Borohydride
作者:Jinsoo Kim、John Bruning、Kevin E. Park、David J. Lee、Bakthan Singaram
DOI:10.1021/ol901677b
日期:2009.10.1
Asymmetric 1,2-reduction of alpha,beta-unsaturated ketones using TarB-NO2 and NaBH4 is reported. Simple cycloalkenones give products in low enantiomeric excess. However, cycloalkenones with alpha-substituents, such as halides, alkyl, and aryl, have been enantioselectively reduced with this system to yield chiral allylic alcohols in enantiomeric excess up to 99%. The starting materials for TarB-NO2 are inexpensive, and the boronic acid can be easily recovered in high yield by a simple acid extraction.
Copper-Catalyzed Preparation of Ketones Bearing a Stereogenic Center in α Position