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Oxidation of Nonactivated Anilines to Generate N‑Aryl Nitrenoids

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posted on 24.02.2020, 21:44 by Tianning Deng, Wrickban Mazumdar, Russell L. Ford, Navendu Jana, Ragda Izar, Donald J. Wink, Tom G. Driver
A low-temperature, protecting-group-free oxidation of 2-substituted anilines has been developed to generate an electrophilic N-aryl nitrenoid intermediate that can engage in C–NAr bond formation to construct functionalized N-heterocycles. The exposure of 2-substituted anilines to PIFA and trifluoroacetic acid or 10 mol % Sc­(OTf)3 triggers nitrenoid formation, followed by productive and selective C–NAr and C–C bond formation to yield spirocyclic- or bicyclic 3H-indoles or benzazepinones. Our experiments demonstrate the breadth of these oxidative processes, uncover underlying fundamental elements that control selectivity, and demonstrate how the distinct reactivity patterns embedded in N-aryl nitrenoid reactive intermediates can enable access to functionalized 3H-indoles or benzazepinones.