Imidazole-aryl coupling reaction via C H bond activation catalyzed by palladium supported on modified magnetic reduced graphene oxide in alkaline deep eutectic solvent
By employing reusable heterogeneous catalyst, modified magnetic reduced graphene oxide-supported palladium catalyst (MRGO@ DAP- AO-Pdll), the regioselective C-5 arylation of imidazoles via CH bondactivation pathway for the preparation of C5-arylated imidazoles has been successfully achieved in alkaline deep eutectic solvent made of potassium carbonate and glycerol under aerobic conditions. Compared
Phosphine-free palladium-catalysed direct 5-arylation of imidazole derivatives at low catalyst loading
作者:Julien Roger、Henri Doucet
DOI:10.1016/j.tet.2009.09.084
日期:2009.11
The regioselective 5-arylation of imidazole derivatives with aryl bromides using a low loading of a phosphine-free palladium catalyst gives a simple and economic access to the corresponding 5-arylimidazoles. The choice of the base and of the solvent was found to be crucial to form these products in high yields. Using KOAc as the base, DMAc as the solvent and only 0.5–0.01 mol % Pd(OAc)2 as the catalyst
Sterically Encumbered Tetraarylimidazolium Carbene Pd-PEPPSI Complexes: Highly Efficient Direct Arylation of Imidazoles with Aryl Bromides under Aerobic Conditions
作者:Xu-Xian He、Yinwu Li、Bei-Bei Ma、Zhuofeng Ke、Feng-Shou Liu
DOI:10.1021/acs.organomet.6b00391
日期:2016.8.22
A series of sterically encumbered tetraarylimidazolium carbene Pd-PEPPSI complexes were conveniently prepared and fully characterized. These sterically encumbered Pd-PEPPSI complexes act as active precatalysts for the direct arylation of imidazoles with aryl bromides under aerobic conditions. The catalytic performance of Pd-PEPPSI complexes in cross-coupling processes is investigated. Under the optimal protocols, the cross-coupling reactions regioselectively produced C5-arylation products in moderate to excellent yields, which could tolerate a wide range of functional aryl bromides.