The synthesis of the novel oxazole building block, 4-bromomethyl-2-chlorooxazole, and its palladium-catalysed cross-coupling reactions to make a range of 2,4-disubstituted oxazoles, is described. Selectivity for the 4-bromomethyl position is observed, with Stille coupling effected in good to excellent yields, or Suzuki coupling in moderate yields, to provide a range of 4-substituted-2-chlorooxazoles. Subsequent coupling at the 2-chloro-position can be achieved through either Stille or Suzuki reactions in excellent yields.

中文翻译：

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4-溴甲基-2-氯恶唑–通用的恶唑交叉偶联单元，用于合成2,4-二取代的恶唑

描述了新型恶唑结构单元4-溴甲基-2-氯恶唑的合成及其钯催化的交叉偶联反应，以制得一系列2,4-二取代的恶唑。观察到4-溴甲基位置的选择性，其中斯蒂勒偶联以良好至优异的产率进行，或铃木偶联以中等产率进行，以提供一系列4-取代的2-氯恶唑。可以通过Stille或Suzuki反应以优异的产率实现随后在2-氯位置的偶联。