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Synfacts 2009(12): 1381-1381  
DOI: 10.1055/s-0029-1218242
Metal-Catalyzed Asymmetric Synthesis and Stereoselective Reactions
© Georg Thieme Verlag Stuttgart ˙ New York

Reversal of Enantioselectivity in the Synthesis of Pyrrolidines

Contributor(s): Mark Lautens, Stephen G. Newman
H. Y. Kim, H.-J. Shih, W. E. Knabe, K. Oh*
Indiana University Purdue University Indianapolis, USA
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Publication History

Publication Date:
20 November 2009 (online)

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Significance

A brucine-derived chiral ligand for the 1,3-dipolar cycloaddition of azomethine ylides with tert-butyl acrylate is reported. When copper(I) is used as a catalyst, the product pyrrolidines are formed with high enantiomeric excess. When silver(I) is used as a catalyst, the other enantiomer can be obtained selectively. Modification of the ligand suggests that N19 and the free alcohols on C21 and C22 are involved in the reaction when copper is used as a catalyst. Under silver catalysis, the alcohol at C22 has little influence on ­reactivity and selectivity.