Institute of Chemical Research of Catalonia (ICIQ), Av. Països Catalans, 16, 43007 Tarragona, Spain.
Chemistry. 2011 Oct 4;17(41):11585-95. doi: 10.1002/chem.201101730. Epub 2011 Sep 1.
α,α-Diphenylprolinol methyl- and trimethylsilyl ethers anchored onto a polystyrene resin have been prepared by a copper-catalyzed azide-alkyne cycloadditions (CuAAC). The catalytic activity and enantioselectivity displayed by the O-trimethylsilyl derivative are comparable to those exhibited by the best known homogeneous catalysts for the addition of aldehydes to nitroolefins and of malonates or nitromethane to α,β-unsaturated aldehydes. The combination of the catalytic unit, the triazole linker, and the polymeric matrix provides unprecedented substrate selectivity, in favor of linear, short-chain aldehydes, when the organocatalyzed reaction proceeds by an enamine mechanism. High versatility is noted in reactions that proceed via an iminium ion intermediate. The catalytic behavior of polystyrene-supported α,α-diphenylprolinol methyl ether was also evaluated in asymmetric Michael addition reactions. As a general trend, the CuAAC immobilization of diarylprolinol ethers onto insoluble polystyrene resins offers important operational advantages, such as high catalytic activity, easy recovery from the reaction mixture by simple filtration, and the possibility of extended reuse.
已通过铜催化的叠氮化物-炔烃环加成（CuAAC）将α，α-二苯基脯氨醇甲基和三甲硅基醚键合到聚苯乙烯树脂上。O-三甲基硅基衍生物显示出的催化活性和对映选择性与醛与硝基烯烃加成以及丙二酸酯或硝基甲烷与α，β-不饱和醛加成的最知名的均相催化剂相当。催化单元、三唑连接子和聚合物基质的组合提供了前所未有的底物选择性，有利于线性、短链醛，当有机催化反应通过烯胺机理进行时。当反应通过亚胺离子中间体进行时，还注意到高的多功能性。聚苯乙烯负载的α，α-二苯基脯氨醇甲基醚的催化行为也在不对称迈克尔加成反应中进行了评估。一般来说，二芳基脯氨醇醚通过 CuAAC 固定在不溶性聚苯乙烯树脂上提供了重要的操作优势，例如高催化活性、通过简单过滤从反应混合物中容易回收以及可能延长重复使用。
