【摘 要】
：
Over the past decade,the organocatalytic enantioselective nitro-Michael addition of ketones or aldehydes to nitroolefins has become an important and powerful tool for the stereocontrolled formation of
【机 构】
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MOE Key Laboratory of Macromolecular Synthesis and Functionalization;Department of Polymer Science a
【出 处】
：
中国化学会第十三届全国有机合成化学学术研讨会
论文部分内容阅读
Over the past decade,the organocatalytic enantioselective nitro-Michael addition of ketones or aldehydes to nitroolefins has become an important and powerful tool for the stereocontrolled formation of carbon-carbon bonds in organic synthesis.Meanwhile,the use of water as the reaction solvent in such reactions has attracted considerable attention in this research field.Although a number of chiral organocatalytic systems,primarily derived from pyrrolidine derivatives,have been successfully developed as efficient catalysts for the asymmetric transformation in aqueous media,the immobilized organocatalysts with good water compatiblity and recyclability reported thus far have been quite limited.In continuation of our investigations in the field of organocatalysis,we herein describe a new class of polymer-bound pyrrolidine-based organocatalysts via cationic ring-opening polymerization (CROP) of the 2-oxazoline monomer containing a propargyl group followed by subsequent click chemistry strategy (Scheme 1).As a proof of concept,these polymer-supported triazolylpyrrolidines were preliminarily tested in the Michael addition of cyclohexanone to nitrostyrene in water.In the presence of 10-20 mol-% organocatalyst and 5 mol-% trifluoroacetic acid,the addition adducts were obtained in good yields (73-92%) with high enantioselectivities (ee ≤ 88%) and diastereoselectivities (syn/anti ratio ≤ 93∶7).Also,the catalyst can be recovered and reused for several catalytic cycles without significantly diminishing its efficiency.
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