A novel organocatalyst for direct asymmetric Michael additions of cyclohexanone to nitroolefins

A novel catalyst combining pyrrolidinyl and cyclohexanediamine was designed and synthesized. Only 5 mol% of catalyst loading was required for enantioselective Michael additions of cyclohexanone and nitroolefins affording desired γ-nitroketones with > 99% yield, up to 91% ee and up to > 99/1 dr under mild conditions. The enantioselectivity of the product could be further improved to > 99% ee after a single recrystallization in petroleum ether/ethyl acetate.

A novel catalyst composed of a chiral pyrrolidinyl and a chiral cyclohexanediamine framework was synthesized and employed as an efficient organocatalyst, and successfully applied in the asymmetric Michael additions of cyclohexanone to nitroolefins affording desired γ-nitroketones with good yields, and good stereoselectivities with a low catalyst loading at room temperature.Figure optionsDownload as PowerPoint slideHighlights
► A novel organocatalyst was designed and synthesized.
► The catalyst contained a chiral pyrrolidinyl and cyclohexanediamine framework.
► It was used in asymmetric Michael reactions between cyclohexanone and nitroolefins.
► The reactions afforded γ-nitroketones with good yields and stereoselectivities.
► The process was performed under mild conditions with low catalyst loading.