CBS Oxazaborolidines

Aldrich ChemFiles 2007, 7.9, 20.

Since 1987, the series of chiral oxazaborolidines known as CBS catalysts (after Corey, Bakshi, and Shibata) have been used for the catalytic reduction of prochiral ketones, imines, and oximes to produce chiral alcohols, amines, and amino alcohols, respectively, in excellent yields and enantiomeric excesses. The chiral Lewis acid generated from o-tolyl-CBS-oxazaborolidine after protonation with trifluoromethanesulfonimide has demonstrated great utility in the enantioselective Diels–Alder reaction (Scheme 1).¹

Scheme 1

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Materials

References

1. (a) Corey, E. J. et al. J. Am. Chem. Soc. 1987, 109, 5551. (b) Corey, E. J. et al. J. Am. Chem. Soc. 1987, 109, 7925. (c) Kirton, E. H. M. et al. Tetrahedron Lett. 2004, 45, 853. (d) Cho, B. T.; Chun, Y. S. Tetrahedron: Asymmetry 1992, 3, 337. (e) Cho, B. T.; Chun, Y. S. J. Chem. Soc., Perkin Trans. 1 1990, 3200. (f) Tillyer, R. D. et al. Tetrahedron Lett. 1995, 36, 4337. (g) Ryu, D. H.; Corey, E. J. J. Am. Chem. Soc. 2003, 125, 6388.

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