Flores Ferrándiz, Jesús, Fiser, Béla, Gómez Bengoa, Enrique, Chinchilla, Rafael
Solvent-Induced Reversal of Enantioselectivity in the Synthesis of Succinimides by the Addition of Aldehydes to Maleimides Catalysed by Carbamate-Monoprotected 1,2-Diamines
European Journal of Organic Chemistry. 2015, 6: 1218-1225. doi:10.1002/ejoc.201403415
URI: http://hdl.handle.net/10045/52887
DOI: 10.1002/ejoc.201403415
ISSN: 1434-193X (Print)
Abstract: 
A simple change in the polarity of the solvent allows both enantiomers of substituted succinimides to be obtained in the enantioselective conjugate addition reaction of aldehydes, mainly α,α-disubstituted, to maleimides catalysed by chiral carbamate-monoprotected trans-cyclohexane-1,2-diamines. Using a single enantiomer of the organocatalyst, both enantiomers of the resulting Michael adducts are obtained in high yields by simply changing the reaction solvent from aqueous DMF (up to 84 % ee) to chloroform (up to 86 % ee). Theoretical calculations are used to explain this uncommon reversal of the enantioselectivity; two transition state orientations of different polarities are differently favoured in polar or nonpolar solvents.
Keywords:Asymmetric catalysis, Organo­catalysis, Michael addition, Enantioselectivity, Solvent effects, Transition states
Wiley-VCH Verlag GmbH & Co. KGaA
info:eu-repo/semantics/article