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Synfacts 2007(4): 0391-0391  
DOI: 10.1055/s-2007-968341
Metal-Catalyzed Asymmetric Synthesis and Stereoselective Reactions
© Georg Thieme Verlag Stuttgart · New York

A New Bifunctional Catalyst - Asymmetric Co(II)-Mediated Wynberg Reaction

Contributor(s): Mark Lautens, Frédéric Ménard
Y.-M. Lin*, J. Boucau, Z. Li, V. Casarotto, J. Lin, A. N. Nguyen, J. Ehrmantraut
University of Toledo, USA
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Publication History

Publication Date:
23 March 2007 (online)

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Significance

A new hemilabile pentadentate ligand was reported where two privileged classes of chiral ligands were coupled to act simultaneously as a Lewis acid and a Lewis base. The quinine salen ligand of 3 can be prepared rapidly in gram quantities. Although applied here to the sole example of a [2+2] cycloaddition between ketene 5 and aldehyde 6, the ligand was shown to be highly efficient. The enantioselective synthesis of substituted β-lactone 7 represents the best ee obtained so far catalytically with a reactive enolizable aliphatic aldehyde like 6.