CBS reduction

The CBS reduction, in full the Corey-Bakshi-Shibata reduction, is an organic reaction which transforms ketones enantioselectively into alcohols. [Corey, E. J.; Shibata, S.; Bakshi, R. K. "J. Org. Chem." 1988, "53", 2861-2863.] ["Organic Syntheses", Coll. Vol. 9, p.676 (1998); Vol. 74, p.50 (1997) ( [http://www.orgsynth.org/orgsyn/prep.asp?prep=cv9p0676 Article] )] [Organic Syntheses, Coll. Vol. 9, p.362 (1998); Vol. 74, p.33 (1997) ( [http://www.orgsynth.org/orgsyn/prep.asp?prep=cv9p0362 Article] ).] This is done by using the so-called CBS catalyst, a bicyclic boron-containing proline derivative, along with diborane as the hydrogen donor. [Mechanistic Aspects of the [http://www.organic-chemistry.org/namedreactions/corey-bakshi-shibata-reduction.shtm CBS reduction] ] [Evans, M. A.; Morken, J. P. "Org. Lett." 2005, "7", 3371-3373.] [For examples see "Organic Syntheses", Coll. Vol. 10, p.448 (2004); Vol. 79, p.72 (2002) ( [http://www.orgsynth.org/orgsyn/prep.asp?prep=v79p0072 Article] )]

The oxazaborolidine reagent which mediates the enantioselective reduction was previously developed by the laboratory of Itsuno, [Itsuno, S.; Ito, K.; Hirao, A.; Nakahama, S. "J. Chem. Soc., Chem. Commun." 1983, "8", 469.] and thus this transformation may more properly be called the Itsuno-Corey oxazaborolidine reduction.

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