Highly Selective Hydrolytic Kinetic Resolution of Terminal Epoxides Catalyzed by Chiral (salen)CoIII Complexes. Practical Synthesis of Enantioenriched Terminal Epoxides and 1,2-Diols
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- 作者：Scott E. Schaus ; Bridget D. Brandes ; Jay F. Larrow ; Makoto Tokunaga ; Karl B. Hansen ; Alexandra E. Gould ; Michael E. Furrow ; and Eric N. Jacobsen
- 刊名：Journal of the American Chemical Society
- 出版年：2002
- 出版时间：February 20, 2002
- 年：2002
- 卷：124
- 期：7
- 页码：1307 - 1315
- 全文大小：116K
- 年卷期：v.124,no.7(February 20, 2002)
- ISSN：1520-5126
文摘
The hydrolytic kinetic resolution (HKR) of terminal epoxides catalyzed by chiral (salen)CoIII complex1·OAc affords both recovered unreacted epoxide and 1,2-diol product in highly enantioenriched form. Assuch, the HKR provides general access to useful, highly enantioenriched chiral building blocks that areotherwise difficult to access, from inexpensive racemic materials. The reaction has several appealing featuresfrom a practical standpoint, including the use of H2O as a reactant and low loadings (0.2-2.0 mol %) of arecyclable, commercially available catalyst. In addition, the HKR displays extraordinary scope, as a wideassortment of sterically and electronically varied epoxides can be resolved to 
99% ee. The corresponding1,2-diols were produced in good-to-high enantiomeric excess using 0.45 equiv of H2O. Useful and generalprotocols are provided for the isolation of highly enantioenriched epoxides and diols, as well as for catalystrecovery and recycling. Selectivity factors (krel) were determined for the HKR reactions by measuring theproduct ee at ca. 20% conversion. In nearly all cases, krel values for the HKR exceed 50, and in severalcases are well in excess of 200.
99% ee. The corresponding1,2-diols were produced in good-to-high enantiomeric excess using 0.45 equiv of H2O. Useful and generalprotocols are provided for the isolation of highly enantioenriched epoxides and diols, as well as for catalystrecovery and recycling. Selectivity factors (krel) were determined for the HKR reactions by measuring theproduct ee at ca. 20% conversion. In nearly all cases, krel values for the HKR exceed 50, and in severalcases are well in excess of 200.