The development of efficient processes for the preparation of structurally diverse axially chiral biaryls has been an important goal in synthetic organic chemistry and asymmetric catalysis. However, in sharp contrast to the well-established open-chain biaryls, the catalytic enantioselective construction of medium-sized bridged biaryls remains underdeveloped. In particular, no enantioselective synthesis of such frameworks possessing a configurationally stable stereogenic C-N axis with step- or pot-economy has been disclosed. Herein, we report a practical synthesis of atropisomeric eight-membered lactam-bridged N-arylindoles through a conceptually intriguing stepwise cut-and-sew strategy. The key to success lies in the development of a silver-catalyzed atroposelective ring-opening/cyclization cascade reaction of N-arylindole lactams with isocyanoacetates to establish C-N axial chirality. This method features operational simplicity, good functional group tolerance, high efficiency, as well as good to high enantiocontrol. It is also noteworthy that these scaffolds exhibit large Stokes shifts, demonstrating their potential applications as fluorescent dyes.

中文翻译：

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通过逐步剪切策略选择性合成八元内酰胺桥N-芳基吲哚

开发制备结构多样的轴向手性联芳基化合物的有效方法一直是合成有机化学和不对称催化的一个重要目标。然而，与成熟的开链联芳基形成鲜明对比的是，中等尺寸桥联联芳基的催化对映选择性结构仍然不发达。特别地，尚未公开具有构型稳定的立体异构CN轴的具有分步或罐式经济的此类框架的对映选择性合成。在此，我们报告了通过概念上有趣的逐步裁剪策略，实际合成了阻转异构八元内酰胺桥N-芳基吲哚。成功的关键在于开发银催化的N-芳基吲哚内酰胺与异氰乙酸酯的间质选择性开环/环化级联反应，以建立CN轴手性。该方法操作简单，官能团耐受性好，效率高，对映体控制良好。还值得注意的是，这些支架表现出大的斯托克斯位移，证明了它们作为荧光染料的潜在应用。