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Synfacts 2006(10): 1059-1059  
DOI: 10.1055/s-2006-949376
Organo- and Biocatalysis
© Georg Thieme Verlag Stuttgart · New York

Enantioselective Intramolecular Cyclopro-panation Using Modified Cinchona Alkaloids

Contributor(s): Benjamin List, Michael Stadler
C. C. C. Johansson, N. Bremeyer, S. V. Ley, D. R. Owen, S. C. Smith, M. J. Gaunt*
University of Cambridge, Pfizer Global Research and Development, Sandwich and Syngenta Jealotts Hill International Research Centre, Bracknell, UK
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Publication History

Publication Date:
21 September 2006 (online)

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Significance

The authors present an organocatalytic, intramolecular route to bicyclic [4.1.0]-alkanes, generating three stereocenters at once. Modified cinchona alkaloids quinine and quinidine are used as catalysts. Moderate to high yields of a single diastereomer are obtained with enantiomeric ratios exceeding 96:4 in all reported cases and for both enantiomers. Moreover, the tricyclic 5-7-6 framework of structures like guanacastepene A or rameswaralide is shown to be easily accessible through a reaction sequence with a cyclo­propanation as the key step.