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Asymmetric C-C bond formation via Darzens condensation and Michael addition using monosaccharide-based chiral crown ethers |
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| Authors: | Pé ter Bakó ,Zsolt RapiGyö rgy Keglevich,Tamá s Szabó Pé ter L. Só ti,Tamá s Ví ghAlajos Gr?n,Tamá s Holczbauer |
| Affiliation: | a Department of Organic Chemistry and Technology, Budapest University of Technology and Economics, PO Box 91, 1521 Budapest, Hungary b Organic Chemical Technology Research Group of the Hungarian Academy of Sciences, Budapest, Hungary c Chemical Research Institute for Chemistry, Hungarian Academy of Sciences, H-1525 Budapest, Hungary |
| Abstract: | Liquid-liquid phase asymmetric Darzens condensations were promoted by d-glucose- and d-mannose-based crown ethers. The corresponding aromatic and heteroaromatic α,β-epoxyketones were obtained with moderate to high enantioselectivities (up to 96%) as well as diastereoselectivities (up to 98:2) under mild reaction conditions. The absolute configurations of several of the epoxyketones were determined by single crystal X-ray analysis. The Michael additions of diethyl acetylaminomalonate to trans-β-nitroalkenes were carried out in a solid-liquid two-phase system in the presence of a d-glucose-based crown catalyst with up to 99% ee. |
| Keywords: | Darzens condensation Michael addition Enantioselectivity Chiral phase-transfer catalysis Crown compounds |
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