A catalytic system utilizing a chelate carbene ligand containing bulk tert-butyl groups is described for palladium-catalyzed Heck and Suzuki coupling reactions. The Heck reaction focused on the coupling of different aryl bromides with mono- and 1,1-disubstituted olefins while the Suzuki reaction involved the coupling of aryl bromides and phenylboronic acid to afford the corresponding biphenyls. The catalyst system performs well with low Pd(OAc)2 levels (0.025 mol% Pd). In all cases with monosubstituted olefins, the trans-configured products were obtained, while the results of Heck reaction of 1,1-disubstituted olefins exhibited a high selectivity favoring the terminal product.

中文翻译：

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1,1'-亚甲基-3,3'-双[(N-(叔丁基)咪唑-2-ylidene]及其在钯催化C-C偶联中的作用

描述了一种使用包含本体叔丁基的螯合卡宾配体的催化系统，用于钯催化的 Heck 和 Suzuki 偶联反应。Heck 反应侧重于不同的芳基溴化物与单和 1,1-二取代烯烃的偶联，而 Suzuki 反应涉及芳基溴化物和苯基硼酸的偶联以提供相应的联苯。该催化剂体系在 Pd(OAc)2 含量低（0.025 mol% Pd）时表现良好。在所有单取代烯烃的情况下，都获得了反式构型的产物，而 1,1-二取代烯烃的 Heck 反应结果显示出有利于最终产物的高选择性。