Tandem rhodium catalysis: exploiting sulfoxides for asymmetric transition-metal catalysis.
Sulfoxides are uncommon substrates for transition-metal catalysis due to their propensity to inhibit catalyst turnover. In a collaborative effort with Ken Houk, we developed the first dynamic kinetic resolution (DKR) of allylic sulfoxides using asymmetric rhodium-catalyzed hydrogenation. A detailed mechanistic analysis of this transformation using both experimental and theoretical methods revealed rhodium to be a tandem catalyst that promoted both hydrogenation of the alkene and racemization of the allylic sulfoxide. Using a combination of deuterium labelling and DFT studies, a novel mode of allylic sulfoxide racemization via a Rh(III)-π-allyl intermediate was identified.
Department of Chemistry, University of California, Irvine, CA 92697, USA. dongv@uci.edu.
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D000475:Alkenes / Q000737:chemistry; D000498:Allyl Compounds / Q000737:chemistry*; D002384:Catalysis; D006865:Hydrogenation; D007700:Kinetics; D012238:Rhodium / Q000737:chemistry*; D013237:Stereoisomerism; D013454:Sulfoxides / Q000737:chemistry*
D000475:Alkenes; D000498:Allyl Compounds; D013454:Sulfoxides; D012238:Rhodium