Synthesis Of Polymer Supported Pyrrolidine Catalysts And Their Application For Michael Addition Reactions

Asymmetric organic synthesis catalyzed by small organic molecule is a bridge toconnect the metal organic catalysis and enzymatic and synthetic chemistry and biologicalchemistry. Because of the feature of environmentally friendly, non-metal and without anymodification of the substrate in the reaction process, it received wide attention fromresearchers. So, dedign, synthesis of highly dfficient organocatalysts and their applicationfor asymmetric organic reactions, is a hot research field of asymmetric organic synthesis.Recently, polymer-supported organocatalysts as a newly emerging branch in thefield of organocatalysis have been attracting intensified attention in relation to design,synthesis, and catalytic performance evaluation. Polymer-suppported orgaocatalysts notonly favor recycle and reuse to offset the drawbacks of organic small-molecules but alsopossess improved catalytic properties owing to their spatial structure, which helps toinject new vitality into the field of organocatalysis.In this paper, firstly, after we carefully studied the structural characteristics ofexcellent supported proline, which had been reported previously, we designed andsynthesized three kinds of supported small molecules organic catalysts, namedpolystyrene pyrrolidine amide catalyst, polyacryamide pyrrolidine amide catalyst andpolyacryamide pyrrolidine-thiourea catalyst.Secondly, in this context, we document the asymmetric Michael addition ofnitroolefins and cyclohexanone with the use of three kinds of supported organocatalysts.The influence of catalysts’ structure, catalyst loading, additives and solvents to the yieldsand enantioselectivities of the adducts was investigated, and a series of results wereobtained. At20℃, toluene as solvent,40mol%of catalyst, adding10mol%of benzoicacid which is the optimized conditions, Michael addition product yield up to88%, eevalue94%, dr value (syn: anti) up to99:1, syn type is the main Michael product. Wesuccessfully achieved highly enantioselective catalysis for asymmetric carbon-carbonbond formation reactions. Under the optimized conditions, we also studied the asymmetric nitro-Michaeladdition reaction of different β-nitroolefins and cyclohexanone. The reactions of differentβ-nitroolefins and cyclohexanone proceeded smoothly in excellent enantioselectivity anddiastereoselectivity (yield up to89%, ee value up to99%, Dr value>99:1) to furnish theMichael adducts. At the same time, we also accumulated a lot of data and experience forthe asymmetric catalysis of Michael addition in the future.