Download PDF
Synfacts 2005(2): 0225-0225  
DOI: 10.1055/s-2005-916115
Metal-Catalyzed Asymmetric Synthesis and Stereoselective Reactions
© Georg Thieme Verlag Stuttgart · New York

Asymmetric Conjugate Addition-Bromination of α,β-Unsaturated Ketones

Contributor(s): Hisashi Yamamoto, Matthew B. Boxer
K. Li, A. Alexakis*
University of Geneva, Switzerland
Further Information

Publication History

Publication Date:
25 October 2005 (online)

    Permissions and Reprints

Significance

In an operationally simple manner, the authors have provided a means for highly enantioselective 1,4-addition, followed by a dia­stereselective trapping of the resulting zinc enolate with molecular bromine. While the addition of Et2Zn was found to proceed with high enantioselectivity (>90% ee for many cases), the diastereoselective halogenation ranged from 48:52 to 70:30. Isomerization of the resulting α-bromo-β-alk­ylketones with DBU was found to increase the ­diastereoselectivities.