Advanced Synthesis & Catalysis · 2007 · 82 citations · 28 references
Natural SciencesChemistryBiocatalysisCatalysisOrganic ChemistryAddition ReactionsOrganic SynthesisSupported CatalystsConjugate AdditionEnantioselective Catalyst DesignEnantioselective SynthesisImidazole ChemistryIminium IonsOrganocatalysis
Abstract Herein we report a new organocatalyst for the asymmetric Michael addition of nitroalkanes to α,β‐unsaturated aldehydes. This catalyst incorporates a basic imidazole group in addition to the secondary amine responsible for activation of the α,β‐unsaturated carbonyl compounds via iminium ion formation. The new organocatalyst is capable of catalyzing the enantioselective carbon‐carbon bond formation with a high degree of enantiocontrol providing products in enantiomeric excesses of up to 92 % and yields of up to to 91 %. These results constitute the best results so far reported for organocatalyzed Michael additions of nitroalkanes to α,β‐unsaturated aldehydes, and provide proof of principle that organocatalysts incorporating two internal basic moieties may find broad application in organocatalyzed Michael additions.
28
Enantioselective Organocatalysis
Peter I. Dalko, Lionel Moisan · Angewandte Chemie International Edition · 2001 · 1.1K citations
Recent Advances in Catalytic Enantioselective Michael Additions
Norbert Krause, Anja Hoffmann‐Röder · Synthesis · 2001 · 946 citations
Enantioselective Conjugate Additions
Mukund P. Sibi, S. Manyem · Tetrahedron · 2000 · 811 citations