Dearomatization of two-dimensional planar aromatic feedstocks is an attractive strategy for the introduction of three-dimensional vectors into chemical scaffolds to expand chemical space for drug discovery. Here, we demonstrate the dearomative dimerization and skeletal rearrangement of quinolines under polysulfide anion photocatalysis, in which the additive dictates the reaction courses. In the presence of formate, dearomative dimerization of quinolines is followed by cyclization to form an sp³-rich polyheterocyclic hybrid of a 2,5-methanobenzo[b]azepine and a tetrahydroquinoline in a net-reductive manner. On the other hand, in the presence of triethylamine instead of formate, sequential dimerization and skeletal rearrangement occurs to afford 4-(3-indolylmethyl)quinolines in a redox-neutral manner. These observations enabled the design of a net-reductive skeletal rearrangement of 4-arylquinolines to 3-(arylmethyl)indoles. Detailed mechanistic investigations revealed that this umpolung transformation from electron-deficient quinolines to electron-rich indoles is mediated via a 1,2-aryl migration/ring-contraction sequence, as opposed to the more commonly invoked neophyl-like rearrangement.

中文翻译：

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由单电子转移触发的喹啉的去异构化及其骨骼重排为吲哚


二维平面芳香族原料的脱芳烃是将三维载体引入化学支架以扩大药物发现的化学空间的一种有吸引力的策略。在这里，我们展示了在多硫化物阴离子光催化下喹啉的脱酰胺二聚化和骨架重排，其中添加剂决定了反应过程。在甲酸盐存在下，喹啉的脱酰胺二聚化后进行环化，以净还原方式形成 2,5-甲烷苯并[b]氮杂畴和四氢喹啉的富含 sp³ 的多杂环杂合物。另一方面，在三乙胺而不是甲酸盐存在的情况下，发生连续二聚化和骨架重排，以氧化还原中性方式得到 4-（3-吲哚甲基）喹啉。这些观察结果使 4-芳基喹啉到 3-（芳基甲基）吲哚的净还原骨架重排的设计成为可能。详细的机制研究表明，这种从缺电子喹啉到富电子吲哚的 umpolung 转变是通过 1,2-芳基迁移/环收缩序列介导的，而不是更常见的 neophyl 样重排。