Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810 (Japan), Fax: (+81) 11-706-3749 http://wwwchem.sci.hokudai.ac.jp/∼orgmet/index.php.
Chemistry. 2014 Jan 20;20(4):1057-65. doi: 10.1002/chem.201304081. Epub 2013 Dec 20.
A silica-supported triphenylphosphane (Silica-3p-TPP) with a Ph3P-type core, immobilized on a silica surface, was synthesized and characterized by nitrogen-absorption measurements and solid-state NMR spectroscopy. The tripodal immobilization constrains the mobility of the phosphane molecule and causes the lone pair on the phosphorus atom to face in the direction perpendicular to the support, resulting in the selective formation of a 1:1 metal-phosphane species that is free from unfavorable steric repulsions caused by the silica surface. Heterogeneous Pd catalysts created in this manner enabled room-temperature Suzuki-Miyaura cross-coupling reactions with unactivated chloroarenes, despite the moderate electronic and steric nature of the Ph3P-based ligands. These catalysts also showed potential in reactions with more challenging substrates under mild conditions. Tripodally immobilized and well-dispersed phosphanes on the silica surface were crucial for high catalytic activity.
一种负载在硅胶表面的三苯基膦（Silica-3p-TPP）被合成出来并通过氮气吸附测量和固态 NMR 光谱进行了表征。该三齿固定化限制了膦分子的迁移性，并导致磷原子上的孤对电子指向垂直于载体的方向，从而选择性地形成了一种 1:1 的金属-膦物种，避免了由于硅胶表面引起的不利的空间位阻。以这种方式制备的非均相 Pd 催化剂能够在室温下实现与未活化的氯代芳烃的 Suzuki-Miyaura 交叉偶联反应，尽管基于三苯基膦的配体具有中等的电子和空间位阻性质。这些催化剂在温和条件下对更具挑战性的底物的反应中也显示出了潜力。硅胶表面上三齿固定化和良好分散的膦对于高催化活性至关重要。
