Generation and Control of Electrophilic N–aryl Nitrenoids to construct 3H-indoles and aziridines

N-Heterocycles are an important array of compounds which widely spread in natural products, pharmaceuticals, and materials. The synthesis of N-heterocycles is interesting and challenging, which motivated the research group and enterprises to develop this area. Driver group developed the construction of N-heterocycles, for example, indoles, indolines, and benzazepinones through the transition metal catalyzed C–N bond formation reaction using aryl azides or nitroarenes. To explore new area of the nitrene chemistry, generation of N-aryl nitrenoid intermediates by oxidation of unactivated anilines was discovered. Exposure of 2-substituted unactivated anilines to PIFA and trifluoroacetic acid under mild temperature triggers nitrenoid formation, followed productive and selective C–NAr bond formation to yield spirocyclic- or fused bicyclic 3H-indoles. The usage of hypervalent iodine reagent motivated us to examine if the same reactivity could be achieved using iodoarene or iodoalkane as catalyst pairing with external oxidants. The I(III)-catalyzed process was developed using only 1 mol % iodobenzene as catalyst and 1.3 equivalent of Selectfluor as oxidant to promote the yields of 3H-indoles and to investigate the relationship between the identity of iodine reagent and diastereoselectivity. Computational calculation was introduced into the explore the reaction mechanism during stay-at-home order. Thanks to the cooperation of mechanistic experiments and calculated energy profile, oxidation site selectivity, origin of diastereoselectivity, and driving force of migration aptitude were illustrated. Guided by the mechanistic study, the N-aryl nitrenoid could be used to pursue intermolecular reaction by transmetalation. Rh2(II)-Catalyzed intermolecular N-aryl aziridination reaction of olefin using unactivated anilines as nitrogen source was discovered and developed to fulfill the gap. A wide range of anilines and heterocyclic amines are tolerated to reacted with di-, tri-, tetrasubstituted olefin to afford N-aryl aziridines in stereospecific, chemo- and diastereoselective manner.