Organocatalytic Asymmetric Michael Additions Of Nitroolefins And Cycloketones

Michael addition is one of the most frequently C-C bond-forming reactions in organic synthesis.Significant efforts have been directed toward the development of organocatalytic asymmetric variant of this reaction since the rediscovery of the organocatalysis at the beginning of 21st century.In this context,we document the asymmetric Michael addition of nitroolefins and cycloketones with the use of pyrrolidine-amide derivatives as a novel class oforganocatalyst.1.Novel bifunctional pyrrolidine-amide derivatives have been designed and synthesized as a new organocatalyst for the asymmetric desymmetrization of prochiral and racemic cyclohexanones with nitroolefins by Michael addition.The reaction condition has been optimized.High isolated yields(up to 90%),enantioselecfivities(up to 93%ee),and diastereoselectivities(up to＞99:1 dr)were obtained under the optimal conditions.Sixteen enantiomerically riched 4-substituent-γ-nitrocycloketone with three chiral centers were synthesized and all compounds were characterized by ¹H NMR,¹³C NMR,and element analysis.2.The catalytic activities of the pyrrolidine-amide derivatives were examined through the direct asymmetric Michael addtion reactions of variousβ-styrene and cyclohexanone in aqueous media without additional organic solvents,.Highy diastereoand enantioselectives in water were obtained under the optimal conditions.