Oxazoles and pyrazines are fundamental heterocycles that widely found in natural products or drugs. In this work, a selective strategy for oxazoles and pyrazines synthesis using α-bromo-1-phenylethanone and ammonium acetate as starting materials was reported. This methodology features mild reaction conditions, readily accessible starting materials and good chemoselectivity. Mechanistic study indicates that this reaction involves a by-product-promoted (BPP) process for the formation of oxazole, that is, the in-situ formed hydrogen bromide (HBr) during the reaction promotes the whole tandem process.

中文翻译：

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从中选择性合成恶唑和吡嗪 $\mathbf{\alpha }$-溴-1-苯基乙酮使用副产物促进策略

恶唑和吡嗪是在天然产物或药物中广泛发现的基本杂环。在这项工作中，报道了一种以α-溴-1-苯基乙酮和乙酸铵为起始原料合成恶唑和吡嗪的选择性策略。该方法的特点是反应条件温和，原料易得，化学选择性好。机理研究表明，该反应涉及形成恶唑的副产物促进（BPP）过程，即反应过程中原位形成的溴化氢（HBr）促进了整个串联过程。