Allylic sulfoxides undergo a reversible 2,3-sigmatropic rearrangement to transiently form an achiral sulfenate ester, ultimately epimerizing the sulfoxide stereocenter. We sought to use this epimerization to perform a dynamic kinetic asymmetric transformation. The success of such a reaction would depend on the rate of epimerization of the allylic sulfoxide as well as the inherent stereoselectivity of the catalyst. Guided by theoretical calculations to predict substituent effects for the sigmatropic rearrangement, we have investigated the asymmetric hydrogenation of allylic sulfoxides that are predicted to undergo fast epimerizations. The optimization and scope of the reaction will be explored, including the generation of multiple chiral centers. Finally, the mechanism of the hydrogenation has been modeled through theoretical calculations, and the role of the sulfoxide as a directing group will be discussed.

Dynamic kinetic resolution of allylic sulfoxides by asymmetric hydrogenation

243rd National Meeting (2012)

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