Two methods for the one-pot synthesis of 2,5-diarylimidazoles by palladium-catalyzed direct C–H arylation of 1-substituted imidazoles with aryl bromides have been devised. The first method, promoted by copper(I) iodide, is best suited for electron-poor aryl bromides, and also allows the 2,5-diarylation of thiazole and oxazole. The use of xylene instead of DMA is the key for the efficiency of the second method, which gives the best results with electron-rich aryl bromides.

中文翻译：

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根据芳基卤化物的电子特征，通过一锅钯催化的直接芳基化反应改进了对称的2,5-二芳基咪唑的合成

已经设计了两种通过钯催化1-取代的咪唑与芳基溴的直接C–H芳基化反应一锅合成2,5-二芳基咪唑的方法。由碘化铜（I）促进的第一种方法最适合于电子贫乏的芳基溴化物，并且还可以使噻唑和恶唑进行2,5-二芳基化。使用二甲苯代替DMA是提高第二种方法效率的关键，对于富电子的芳基溴化物，该方法可获得最佳结果。