Catalytic Asymmetric Bromination and Chlorination of β‐Ketoesters
- 21 April 2004
- journal article
- research article
- Published by Wiley in Chemistry – A European Journal
- Vol. 10 (9) , 2133-2137
- https://doi.org/10.1002/chem.200305759
Abstract
The first general catalytic asymmetric bromination and chlorination of β-ketoesters has been developed. The reactions proceed for both acyclic and cyclic β-ketoesters catalyzed by chiral bisoxazolinecopper(II) complexes giving the corresponding optically active α-bromo- and α-chloro-β-ketoesters in high yields and moderate to good enantioselectivities. For the optically active chlorinated products the isolated yields are in the range of 88–99 % and the enantiomeric excesses up to 77 % ee, while the optically active brominated adducts are formed in 70–99 % isolated yield and up to 82 % ee. Based on the absolute configuration of the optically active products, the face selectivity for the catalytic enantioselective halogenation is discussed based on a bidentate coordination of the β-ketoester to the chiral catalyst and a X-ray structure of chiral α,γ-diketoesterenolatebisoxazolinecopper(II) complex.Keywords
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