Synthesis of substituted chiral chromans via organocatalytic kinetic resolution of?racemic 3-nitro-2-aryl-2H-chromenes with ketones catalyzed by pyrrolidinyl-camphor-derived organocatalysts

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• 作者：Dhananjay R. Magar ; Kwunmin Chen ; ^{kchen@ntnu.edu.tw}
• 关键词：Kinetic resolution ; Organocatalysis ; Michael addition ; Chromenes ; Chromans
• 刊名：Tetrahedron
• 出版年：2012
• 出版时间：22 July, 2012
• 年：2012
• 卷：68
• 期：29
• 页码：5810-5816
• 全文大小：357 K

文摘

Efficient kinetic resolution of racemic 2-aryl-3-nitro-2H-chromenes (1a-l) has been explored with the pyrrolidinyl-camphor derivative 2b as a bifunctional organocatalyst under neat conditions in the presence of AcOH at 0?¡ãC. In general, the organocatalytic asymmetric Michael addition of ketones proceeded smoothly to give the functionalized Michael adducts (3a-n) with good-to-high diastereo- and enantioselectivities (up to 92:8 dr, 93 % ee, and 47 % yield). The less reactive chromenes (S)-1a-h, k, l and (R)-1i-j were recovered in high chemical yields and moderate optical purity (up to 42 % chemical yield and 72 % ee).