The 3-(4-(methoxycarbonyl)phenyl)triazapentalene is a highly fluorescent small molecule which is readily accessible via a two-step synthesis. In the search for postfunctionalization methods, a radical CH-arylation with diazonium salts was attempted. However, azo coupling resulted in a ring-degenerate rearrangement toward a 2-aryl-4-azotriazapentalene, which was confirmed via crystallographic analysis. A mechanism involving the generation of a nitrilimine is proposed. In addition, reduction of the azo group led to cleavage of the triazapentalene core. The present results further demonstrate the sensitivity of the triazapentalene fluorophore.

中文翻译：

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3-芳基-1,3a，6a-三氮杂戊烯的偶氮偶合反应导致的环简并重排。

3-（4-（甲氧基羰基）苯基）三氮杂戊烯是高荧光的小分子，可通过两步合成容易地获得。在寻找后功能化方法中，尝试了用重氮盐进行自由基CH-芳基化。然而，偶氮偶合导致朝向2-芳基-4-偶氮三氮杂戊烯的环简并重排，这通过晶体学分析证实。提出了涉及腈亚胺生成的机理。另外，偶氮基团的还原导致三氮杂戊烯核的裂解。本结果进一步证明了三氮杂戊烯荧光团的敏感性。