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Synfacts 2006(4): 0387-0387  
DOI: 10.1055/s-2006-932102
Bioorganic Chemistry and Organocatalysis
© Georg Thieme Verlag Stuttgart · New York

Enantioselective [4+2] Cycloadditions of Ketenes with o-Quinones

Contributor(s): Benjamin List, Subhas Chandra Pan
T. Bekele, M. H. Shah, J. Wolfer, C. J. Abraham, A. Weatherwax, T. Lectka*
Johns Hopkins University, Baltimore, USA
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Publication History

Publication Date:
24 March 2006 (online)

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Significance

Here the authors report a catalytic, enantioselective [4+2] cycloaddition of o-quinones with chiral 1-ammonium enolates generated in situ from the reaction of acid chlorides with a cinchona alkaloid based catalyst and Hünig’s base. The cycloadducts are converted into chiral α-hydroxyesters in a two-step alcoholysis/oxidation sequence with full preservation of optical purity. With 10 mol% of the catalyst 1, high yields and excellent enantioselectivities are obtained for different aliphatic and aromatic acid chlorides.