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'Click' Immobilization of Organometallic Pincer Catalysts for C-C Coupling Reactions

机译：“点击”固定化用于C-C偶联反应的有机金属钳形催化剂

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摘要

Model systems for the simple, high-yielding, efficient "click" immobilization of homogeneous pincer catalysts are demonstrated. We present the synthesis of azide- and isocyanate-functionalized high pore volume, low surface area silica materials. Both para-ethynyl-functionalized palladium and platinum pincer organometallics (pincer = [C6H3(CH2NMe2)(2)-2,6](-)) were coupled with azido-functionalized silica material, yielding the corresponding tethered complexes in high yields with no complex degradation. Analogous para-alcohol-functionalized palladium and platinum pincer complexes were coupled with isocyanate-functionalized silica material to yield immobilized organometallics in high yields. The acquired immobilized organometallic pincer complexes were characterized using various techniques (solid-state IR and NMR, elemental content analysis, surface area measurements). Palladium-containing materials were applied as Lewis acid catalysts in the double Michael addition reaction between ethyl cyanoacetate and methyl vinyl ketone. When measured on a per palladium site basis, the novel materials were found to be as active as the homogeneous forms of the catalyst. This led to the discovery that one of the support materials, with no palladium organometallic units, however, with linker triazole groups present, was also an active catalyst, albeit with slightly diminished activity compared to the palladium-containing material. The palladium-containing materials were also applied in allylic stannylation catalysis and were found to be active catalysts, approximately three times slower than the homogeneous catalysts when measured on a per palladium site basis. The support material was not found to be an active catalyst in this reaction. The immobilized palladium catalysts have been applied sequentially for the two-step conversion of an allyl chloride to an allylic alkylation product.
机译：演示了用于简单，高产，有效的“均一”钳式催化剂固定化的模型系统。我们介绍了叠氮化物和异氰酸酯官能化的高孔体积，低表面积二氧化硅材料的合成。对乙炔基官能化的钯和铂钳形有机金属化合物（钳形[C6H3（CH2NMe2）（2）-2,6]（-））都与叠氮基官能化的二氧化硅材料偶联，可以高产率得到相应的束缚配合物复杂的降解。将类似的对位醇官能化的钯和铂钳夹配合物与异氰酸酯官能化的二氧化硅材料偶联，以高产率获得固定化的有机金属化合物。使用各种技术（固态IR和NMR，元素含量分析，表面积测量）对获得的固定化有机金属钳形复合物进行表征。在氰基乙酸乙酯和甲基乙烯基酮之间的双迈克尔加成反应中，将含钯材料用作路易斯酸催化剂。当以每钯位点为基础进行测量时，发现该新型材料与催化剂的均相形式一样具有活性。这导致发现，尽管与含钯材料相比活性稍有降低，但不存在钯有机金属单元但具有连接基三唑基团的一种载体材料也是活性催化剂。含钯材料也用于烯丙基甲锡烷基化催化，被发现是活性催化剂，当以每个钯位点为基础测量时，其速度比均相催化剂慢约三倍。在该反应中未发现载体材料是活性催化剂。固定的钯催化剂已经被顺序地用于烯丙基氯到烯丙基烷基化产物的两步转化。

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