†Center of Advanced Nanocatalysis (CAN), University of Science and Technology of China, Hefei 230026, China.
‡Department of Chemistry, Tsinghua University, Beijing 100084, China.
J Am Chem Soc. 2015 Mar 25;137(11):3791-4. doi: 10.1021/jacs.5b01391. Epub 2015 Mar 17.
Previous studies have shown that crystal planes of heterogeneous catalysts could display enhanced activity, such that higher turnover or chemoselectivity could be achieved. Here we report an example where the reaction stereoselectivity was significantly affected by the catalyst crystal planes. In copper-catalyzed deoxygenation reaction of aromatic epoxides, copper cubes, wires, and plates gave the olefin products with different cis/trans selectivities, whereas homogeneous copper catalysts showed poor selectivity. Scanning tunneling microscope and density functional theory studies revealed that the different adsorption mode and higher adsorption strength of epoxide oxygen on Cu{100} plane were responsible for the observed variation of selectivity. The copper-catalyzed deoxygenation reaction provided new practical access to cis-olefins from readily available aromatic epoxides. Our work also indicated that nanocrystal catalysts may provide useful stereochemical control in organic reactions.
先前的研究表明，多相催化剂的晶面可以表现出增强的活性，从而可以实现更高的转化率或化学选择性。在这里，我们报告了一个例子，其中反应的立体选择性受到催化剂晶面的显著影响。在铜催化的芳基环氧化物的脱氧反应中，铜立方体、铜丝和铜片给出了具有不同顺/反选择性的烯烃产物，而均相铜催化剂的选择性较差。扫描隧道显微镜和密度泛函理论研究表明，环氧基氧在 Cu{100}面上的不同吸附模式和更高的吸附强度是导致选择性变化的原因。铜催化的脱氧反应为从易得的芳基环氧化物中获得顺式烯烃提供了新的实用途径。我们的工作还表明，纳米晶体催化剂可能为有机反应提供有用的立体化学控制。
