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Synfacts 2008(8): 0875-0875
DOI: 10.1055/s-2008-1078540
DOI: 10.1055/s-2008-1078540
Organo- and Biocatalysis
© Georg Thieme Verlag
Stuttgart ˙ New York
Dynamic Kinetic Resolution in an Asymmetric Michael-Michael Cascade
J. Wang, H. Xie, H. Li, L. Zu, W. Wang*
University of New Mexico, Albuquerque, USA
Further Information
Publication History
Publication Date:
23 July 2008 (online)
Significance
A highly diastereo- and enantioselective Michael-Michael reaction cascade of nitroalkenes and trans-3-(2-mercaptophenyl)-2-propenoic acid ethyl esters catalyzed by a chiral cinchona alkaloid thiourea 1 is described. The process proceeds via non-covalent hydrogen-bond interactions and results in the formation of enantioenriched thiochromanes in good yields of up to 99% and excellent enantioselectivities (er = 96:4 to 99.5:0.5). The observed diastereomeric ratios were >30:1 in the majority of cases. As reason for the high selectivity a dynamic kinetic resolution mediated retro-Michael-Michael-Michael cascade was proposed and confirmed in an experiment.