Palladium on Calcium Carbonate Combined to 2-Hydroxypropyl-α/β-cyclodextrins: A Selective Catalytic System for Aqueous Heck Coupling and Hydroarylation
作者:Jaqueline D. Senra、Luiz Fernando B. Malta、Andréa Luzia F. Souza、Lúcia C. S. Aguiar、O. A. C. Antunes
DOI:10.1002/adsc.200800472
日期:2008.11.3
ligand-free aqueous Heck reactions using hydroxypropylated cyclodextrins (HPCDs) and palladium on calcium carbonate (Pd/CaCO3) is highlighted. Remarkably, stereo- and chemoselectivities could be tuned by the cavity size of cyclodextrins, exploiting the relevance of host-guest interactions. UV-Vis experiments have led to strong evidence concerning an interplay between Pd(II) and α-HPCD, possibly ascribed
重点介绍了使用羟丙基化环糊精(HPCD)和碳酸钙钯(Pd / CaCO 3)进行的无配体含水Heck反应的有效,选择性和可回收的催化体系。值得注意的是,利用宿主-客体相互作用的相关性,可以通过环糊精的腔尺寸来调节立体选择性和化学选择性。UV-Vis实验已经得到有关Pd(II)与α-HPCD之间相互作用的有力证据,这可能归因于CD的减少/稳定作用。出乎意料的是,加氢芳基化是丙烯腈的首选途径,丙烯腈无需通常的氢化物供体即可获得3-苯基丙腈衍生物。最后,通过 AAS使得能够定义主要的同质机制,其中观察到TON超过5000。