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Synfacts 2011(8): 0853-0853  
DOI: 10.1055/s-0030-1260735
Metal-Catalyzed Asymmetric Synthesis and Stereoselective Reactions
© Georg Thieme Verlag Stuttgart ˙ New York

Cooperative Transition-Metal and Chiral Brønsted Acid Catalysis

Contributor(s):Mark Lautens, Patrick T. Franke
S. Zhou, S. Fleischer, K. Junge, M. Beller*
Leibniz-Institut für Katalyse an der Universität Rostock, Germany
Cooperative Transition-Metal and Chiral Brønsted Acid Catalysis: Enantioselective Hydrogenation of Imines to Form Amines
Angew. Chem. Int. Ed.  2011,  50:  5120-5124  
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Publication History

Publication Date:
20 July 2011 (online)

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Key words

asymmetric catalysis - hydrogenation - imines - iron

Significance

The authors report a protocol for the enantioselective hydrogenation of various ketimines in the presence of a chiral Brønsted catalyst and a well-defined nonchiral iron catalyst. This work demonstrates that enantioselective reduction reactions with hydrogen can be performed without employing precious-metal catalysts and chiral ligands yielding products with high yields and enantioselectivities.

Comment

NMR spectroscopic studies revealed the formation of complex 1 when a 1:1 mixture of TRIP and the Knölker iron complex (cat. 1) were mixed. Upon addition of a ketimine to the reaction mixture, the formation of complex 2 was observed. These results suggest that a cooperative catalytic system is operative for this transformation.

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