The microwave-assisted reaction of 2-nitroimidazole with 3-bromophenacyl bromide in the presence of potassium carbonate as a base and dimethylformamide as a solvent afforded 2-(3-bromophenyl)imidazo[2,1-b]oxazole. The formation of this compound was explained via a domino mechanism comprising an initial N-alkylation reaction of the imidazole substrate, followed by the base-promoted deprotonation of the position adjacent to the carbonyl to give an enolate anion that finally cyclizes via an intramolecular SNAr reaction, with the loss of the nitro group as potassium nitrite. Then, the proposed 1-(3-bromophenacyl)-2-nitroimidazole intermediate could be isolated by reducing the reaction time and was shown to be a precursor of the imidazo[2,1-b]oxazole final product.

中文翻译：

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2-(3-溴苯基)咪唑并[2,1-b]恶唑

在碳酸钾作为碱和二甲基甲酰胺作为溶剂存在下，2-硝基咪唑与 3-溴苯甲酰溴的微波辅助反应得到 2-(3-溴苯基)咪唑并[2,1-b]恶唑。这种化合物的形成是通过多米诺骨牌机制解释的，该机制包括咪唑底物的初始 N-烷基化反应，然后是碱促进的与羰基相邻位置的去质子化，得到烯醇根阴离子，最终通过分子内 SNAr 反应环化, 随着硝基的损失成为亚硝酸钾。然后，所提出的 1-(3-bromophenacyl)-2-nitroimidazole 中间体可以通过减少反应时间来分离，并被证明是咪唑并 [2,1-b] 恶唑最终产物的前体。