Synfacts 2009(2): 0178-0178  
DOI: 10.1055/s-0028-1087630
Metal-Catalyzed Asymmetric Synthesis and Stereoselective Reactions
© Georg Thieme Verlag Stuttgart ˙ New York

Lewis Base Assisted Brønsted Base: Phosphine Oxides and La-Aryloxides

Contributor(s): Hisashi Yamamoto, Joshua N. Payette
H. Morimoto, T. Yoshino, T. Yukawa, G. Lu, S. Matsunaga*, M. Shibasaki*
The University of Tokyo, Japan
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22. Januar 2009 (online)


Combined acid and base catalysis is a well-established concept which has led to the development of highly reactive systems. However, utilization of a Lewis base to activate a Brønsted base in a catalytic system is genuinely rare. The authors report that addition of a bidentate phosphine oxide Lewis base to a lanthanum aryl oxide produces a highly reactive catalyst for the anti-­selective Mannich-type reaction. In control experiments, with the absence of Lewis base, La(OAr)3 gives both poor reactivity and diastereoselectivity.