ORGN 384 |
| Sulfones with β-stereocenters are important compounds in organic chemistry, providing valuable intermediates in the synthesis of biologically active molecules and natural products. These versatile synthons are commonly found in multi-stage transformations because they can be converted into several functionalities by alkylation, halogenation, oxidation and desulfonylation reactions and by Julia olefinations. However, few catalytic enantioselective reactions to generate this moiety have been found in the literature. Consequently, we have developed a copper-catalyzed hydrosilylation approach that could be safely performed at ambient pressure and temperature. Our group has shown that Me-DuPHOS monoxide (1) can generate high levels of enantiocontrol in the copper-mediated addition of diorganozinc reagents on phosphinoylimines and nitroalkenes. Herein, we describe a study directed toward the enantioselective conjugate reduction of β,β-disubstituted vinyl sulfones using the Me-DuPHOS monoxide·Cu complex as the catalyst. Enantiomeric excesses as high as 99% and isolated yields reaching 97% are achieved with phenylsilane as a stoichiometric reductant.
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Asymmetric Reactions and Syntheses
8:00 AM-12:00 PM, Tuesday, August 21, 2007 BCEC -- 253C, Oral
Division of Organic Chemistry |
