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Asymmetric Oxidation

Asymmetric Oxidation of Di-tert-butyl Disulfide

The seminal work of Ellman and coworkers provided the first example of the catalytic asymmetric oxidation of tert-butyl disulfide. The desymmetrization involves reaction of tert-butyl disulfide with catalytic VO(acac)2 and a chiral indanol ligand in the presence of hydrogen peroxide as the stoichiometric oxidant (Scheme 1). Upon monoxidation to provide tert-Butyl tert-butanethiosulfinate, the sulfur-sulfur bond is cleaved via displacement with LiNH2 to afford the sulfonamide. The sulfonamides are often reacted with aldehydes to provide upon addition of organometallic reagents and deprotection, chiral amines (one of many uses of chiral sulfinimines). This sequence has been demonstrated to be effective on a large scale, utilizes relatively non-toxic solvents such as acetone (first step), and is economically feasible.


Scheme 1.

References

  1. (a) Weix, D. J.; Ellman, J. A. Org. Lett. 2003, 5, 1317. (b) Weix., D. J.; Ellman, J. A. Org. Syn. 2005, 82, 157. (c) Cogan, D. A.; Liu, G.; Kim, K.; Backes, B. J.; Ellman, J. A. J. Am. Chem. Soc. 1998, 120, 8011. (d) Morton, D.; Stockman, R. A. Tetrahedron 2006, 62, 8869.
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