The development of regiodivergent methods that allow access to different structures from a single substrate through intramolecular processes is crucial for accelerating new molecule discovery, as well as making processes more sustainable and efficient in terms of waste production and economy. In this study, we report a novel regiodivergent cyclization procedure to access two distinct azapolyaromatic regioisomers from 2-alkynylazobenzenes. The key to achieving this regiodivergence lies in the presence or absence of a gold catalyst. The irradiation with visible light of 2-alkynylazobenzenes in the presence of a Ir photocatalyst affords 11H-indolo[1,2-b]indazoles, whereas under similar conditions with AuCl₃, indazolo[2,3-a]quinolines are produced. Control experiments and DFT calculations suggest that both transformations operate through different reaction mechanisms: the formation of 11H-indolo[1,2-b]indazoles involves a radical mechanism, whereas the formation of indazolo[2,3-a]quinolines appears to proceed predominantly through a polar mechanism. This transformation enables the one-step conversion of simple 2-alkynylazobenzenes into diverse azapolyaromatic structures via an intramolecular visible light-promoted process, holding significant potential for new nitrogenated heterocycles.

中文翻译：

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用光塑造循环：四环氮杂芳香族化合物的区域发散方法


开发区域发散方法，允许通过分子内过程从单个底物获得不同的结构，这对于加速新分子的发现以及在废物产生和经济方面使过程更加可持续和高效至关重要。在这项研究中，我们报道了一种新的区域发散环化程序，用于从 2-炔基偶氮苯中获得两种不同的氮杂多环芳族区域异构体。实现这种区域差异的关键在于是否存在金催化剂。在 Ir 光催化剂存在下用可见光照射 2-炔基氮苯得到 11个 H-吲哚[1,2-b]吲哚唑，而在与 AuCl₃ 类似的条件下，产生吲唑并[2,3-a]喹啉。对照实验和 DFT 计算表明，这两种转化都通过不同的反应机制进行：11H-吲哚并[1,2-b]吲哚唑的形成涉及自由基机制，而吲唑并[2,3-a]喹啉的形成似乎主要通过极性机制进行。这种转化能够通过分子内可见光促进过程将简单的 2-炔基偶氮苯一步转化为多种氮杂多环芳烃结构，为新的氮化杂环具有重要潜力。