Corey-Bakshi-Shibata Reduction
Itsuno-Corey Reduction

The enantioselective reduction of ketones using borane and a chiral oxazaborolidine as catalyst (CBS catalyst). Usually, MeCBS is used (R'' = Me, but selectivity may be increased by varying this substituent).

Mechanism of the Corey-Bakshi-Shibata Reduction

The mechanism depicted (E. J. Corey, C. J. Helal, Angew. Chem. Int. Ed., 1998, 37, 1986-2012. DOI) portrays the rationale for the enantioselectivity and high reaction rates, which are influenced only by the CBS catalyst. This catalyst is a combination of both a Lewis acid and a chiral auxiliary!