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Synfacts 2008(6): 0641-0641  
DOI: 10.1055/s-2007-1072757
Organo- and Biocatalysis
© Georg Thieme Verlag Stuttgart · New York

Bisphosphoric Acid - An Intriguing Catalyst Motif

Contributor(s): Benjamin List, Corinna Reisinger
X.-H. Chen, W.-Q. Zhang, L.-Z. Gong*
University of Science and Technology of China, Hefei, Chengdu Institute of Organic Chemistry and Graduate School of Chinese Academy of Sciences, Beijing, P. R. of China
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Publication History

Publication Date:
21 May 2008 (online)

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Significance

A Brønsted acid catalyzed three-component asymmetric 1,3-dipolar cycloaddition reaction between aldehydes 1, α-amino esters 2, and maleates 3 is described. The new chiral bisphosphoric acid 4 derived from linked (R)-BINOL was used as catalyst. Substituted pyrrolidines 5 are obtained as endo diastereomers in good to high yields and enantioselectivities. The use of an aliphatic aldehyde (1, R1 = Cy) leads to somewhat decreased enantioselectivity (er = 88:12). Mechanistically, the reaction proceeds via an azomethine ylide dipole, which is generated from the corresponding azomethine in presence of a bisphosphoric acid (see scheme).