Arylation is a fundamental reaction that can be mostly fulfilled by electrophilic aromatic substitution and transition-metal-catalysed aryl functionalization. Although the azo group has been used as a directing group for many transformations via transition-metal-catalysed aryl carbon–hydrogen (C–H) bond activation, there remain significant unmet challenges in organocatalytic arylation. Here, we show that the azo group can effectively act as both a directing and activating group for organocatalytic asymmetric arylation of indoles via formal nucleophilic aromatic substitution of azobenzene derivatives. Thus, a wide range of axially chiral arylindoles have been achieved in good yields with excellent enantioselectivities by utilizing chiral phosphoric acid as catalyst. Furthermore, highly enantioenriched pyrroloindoles bearing two contiguous quaternary chiral centres have also been obtained via a cascade enantioselective formal nucleophilic aromatic substitution–cyclization process. This strategy should be useful in other related research fields and will open new avenues for organocatalytic asymmetric aryl functionalization.

芳基化是基本的反应，大部分可通过亲电子芳族取代和过渡金属催化的芳基官能化来完成。尽管偶氮基已被用作通过过渡金属催化的芳基碳氢键（C–H）键活化的许多转化的导向基团，但在有机催化芳基化方面仍存在未解决的重大挑战。在这里，我们表明，偶氮基可以通过偶氮苯衍生物的正式亲核芳族取代有效地充当吲哚的有机催化不对称芳基化的导向和活化基团。因此，通过使用手性磷酸作为催化剂，已经以良好的收率和优异的对映选择性获得了多种轴向手性芳基吲哚。此外，通过级联对映选择性正式的亲核芳族取代-环化过程，还获得了带有两个连续的季手性中心的高度对映体富集的吡咯并吲哚。该策略应在其他相关研究领域中有用，并将为有机催化不对称芳基官能化开辟新途径。