Cinchona Squaramide-Based Chiral Polymers as Highly Efficient Catalysts in Asymmetric Michael Addition Reaction
Cinchona Squaramide-Based Chiral Polymers as Highly Efficient Catalysts in Asymmetric Michael Addition Reaction
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DOI：
10.1021/acsomega.8b00398
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发表时间：
2018-04
期刊：
影响因子：
4.1
通讯作者：
Mohammad Ullah;S. Itsuno
中科院分区：
文献类型：
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作者：
Mohammad Ullah;S. Itsuno
我们合成了一种新型的手性聚合物，其主链中含有一种基于金鸡纳的方酰胺。我们设计了一种新的金鸡纳方酰胺二聚体，它含有两个金鸡纳方酰胺单元连接的二胺。金鸡纳方酰胺二聚体中的烯属双键用于与芳族二碘化物的Mizoroki-Heck（MH）聚合。金鸡纳方酰胺二聚体和芳香族二碘化物的MH聚合进行得很好，以良好的产率得到相应的手性聚合物。研究了手性聚合物对不对称Michael加成反应的催化活性。详细讨论了高分子催化剂的方酰胺结构对催化性能的影响。考察了手性聚合物结构对不对称反应的催化活性和对映选择性的影响。以高分子金鸡纳方酰胺为催化剂，成功地催化了β-酮酯与硝基烯烃的不对称Michael加成反应，得到了相应的Michael加成物，收率高，对映体和非对映体选择性好.聚合物催化剂不溶于常用的有机溶剂，易于从反应混合物中回收并重复使用数次而不损失催化活性。
We have synthesized novel chiral polymers containing a cinchona-based squaramide in the main chain. We designed a novel cinchona squaramide dimer that contains two cinchona squaramide units connected by diamines. The olefinic double bonds in the cinchona squaramide dimer were used for Mizoroki–Heck (MH) polymerization with aromatic diiodides. The MH polymerization of the cinchona squaramide dimer and aromatic diiodide proceeded well to give the corresponding chiral polymers in good yields. The catalytic activity of the chiral polymers was investigated for asymmetric Michael addition reactions. The effect of the squaramide structure of the polymeric catalyst on the catalytic performance is discussed in detail. We have surveyed the influence of the chiral polymer structure on the catalytic activity and enantioselectivity of the asymmetric reaction. The asymmetric Michael addition of β-ketoesters to nitroolefins was successfully catalyzed by polymeric cinchona squaramide organocatalysts to obtain the corresponding Michael adducts in good yields with excellent enantio- and diastereoselectivities. The polymeric catalysts were insoluble in commonly used organic solvents and easily recovered from the reaction mixture and reused several times without the loss of catalytic activity.