Enantioselective Sulfoxidation as a Probe for a Metal-Based Mechanism in H2O2-Dependent Oxidations Catalyzed by a Diiron Complex
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- 作者：Carole Duboc-Toia ; Sté ; phane Mé ; nage ; Raymond Y. N. Ho ; Lawrence Que ; Jr. ; Claude Lambeaux ; and Marc Fontecave
- 刊名：Inorganic Chemistry
- 出版年：1999
- 出版时间：March 22, 1999
- 年：1999
- 卷：38
- 期：6
- 页码：1261 - 1268
- 全文大小：357K
- 年卷期：v.38,no.6(March 22, 1999)
- ISSN：1520-510X
文摘
The catalytic properties of the diiron complex 1, Fe2OL4(H2O)2(ClO4)4 with L = (-)-4,5-pinenebipyridine, achiral bipyridine derivative, have been investigated. Complex 1 efficiently catalyzes the oxidation of aryl sulfidesto the corresponding sulfoxides by hydrogen peroxide, with yields ranging from 45 to 90% based on the oxidant.Furthermore the reactions were enantioselective and produced a mixture of sulfoxide enantiomers with significantenantiomeric excesses. The largest ee value (40%) was found in the case of p-bromophenyl methyl sulfide. Optimalee's were obtained in polar solvents and at low temperature (below 0 
C), when the excess of the oxidant waslimited. The observation of (i) a saturation kinetics with respect to both sulfide and H2O2 concentrations, (ii) alinear Hammett correlation of the initial Vmax values with 
p values, for a series of p-substituted aryl methylsulfides, (iii) iron-peroxo complexes, characterized by light absorption and Raman resonance spectroscopies,during reaction of complex 1 with H2O2, and (iv) a saturation kinetics with respect to sulfide during oxidation ofsulfide into sulfoxide by the iron-peroxo complexes led us to propose that the iron-peroxo moiety is the actualoxygen atom donor to the substrate, thus explaining the enantioselective control of the catalytic reaction. Thesedata demonstrate that oxidations by non heme diiron complexes can proceed through metal-based pathways andcan thus be made stereoselective.
C), when the excess of the oxidant waslimited. The observation of (i) a saturation kinetics with respect to both sulfide and H2O2 concentrations, (ii) alinear Hammett correlation of the initial Vmax values with p values, for a series of p-substituted aryl methylsulfides, (iii) iron-peroxo complexes, characterized by light absorption and Raman resonance spectroscopies,during reaction of complex 1 with H2O2, and (iv) a saturation kinetics with respect to sulfide during oxidation ofsulfide into sulfoxide by the iron-peroxo complexes led us to propose that the iron-peroxo moiety is the actualoxygen atom donor to the substrate, thus explaining the enantioselective control of the catalytic reaction. Thesedata demonstrate that oxidations by non heme diiron complexes can proceed through metal-based pathways andcan thus be made stereoselective.