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Synfacts 2006(12): 1242-1242  
DOI: 10.1055/s-2006-955634
Metal-Catalyzed Asymmetric Synthesis and Stereoselective Reactions
© Georg Thieme Verlag Stuttgart · New York

Spirophosphonites as Chiral Ligands for Enamine Hydrogenation

Contributor(s): Mark Lautens, Andrew Martins
G.-H. Hou, J.-H. Xie, L.-X. Wang, Q.-L. Zhou*
Nankai University, Tianjin, P. R. of China
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Publication History

Publication Date:
22 November 2006 (online)

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Significance

A variety of 1-(dialkyl)amino-1,2-diarylethenes (N,N-dialkylenamines) were quantitatively converted into chiral 1-(dialkyl)amino-1,2-diarylethanes (chiral tertiary amines) in the presence of a [Rh(cod)2]BF4/spirophosphonite catalyst system under 10 atm of H2. Additives played a crucial role in enhancing reactivity and enantioselectivity, as 2 mol% I2 and 20 mol% AcOH afforded the best results. The observed enantioselectivities ranged from good to excellent, and better results were obtained when Ar1 contained electron-donating groups and/or Ar2 contained electron-withdrawing groups.