Organocatalytic Enantioselective Cascade Michael-Alkylation Reactions: Synthesis of Chiral Cyclopropanes and Investigation of Unexpected Organocatalyzed Stereoselective Ring Opening of Cyclopropanes
Hexin Xie, Liansuo Zu, Hao Li, Jian Wang and Wei Wang*
*Department of Chemistry and Chemical Biology, University of
New Mexico, Albuquerque, New Mexico 87131-0001, Email: wwang
unm.edu
H. Xie, L. Zu, H. Li, J. Wang, W. Wang, J. Am. Chem. Soc., 2007, 129, 10886-10894.
DOI: 10.1021/ja073262a
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Abstract
An organocatalytic asymmetric cascade Michael reaction of α,β-unsaturated aldehydes with bromomalonates, efficiently catalyzed by chiral diphenylprolinol TMS ether in the presence of base 2,6-lutidine, gives cyclopropanes in high enantio- and diastereoselectivities. Using NaOAc as base, a spontaneous ring-opening of cyclopropanes leads to (E) α-substituted malonate α,β-unsaturated aldehydes.
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proposed mechanism
Key Words
Organocatalysis, Cyclopropanes, Active Methylenes
ID: J48-Y2007-2950
