Modular Defluorinative Annulation Enabled by a Dearomative Rearrangement: Diversified Synthesis of Azaheterocycles

The development of efficient and rapid construction of diverse N-heterocyclic scaffolds from simple starting materials has stimulated sustained enthusiasm from the chemical community. Herein we report a diversity-oriented defluorinative annulation triggered by Lewis base-promoted hydroalkoxylation/[3, 3]-sigmatropic rearrangement of fluorinated O-alkenyl-N-arylhydroxylamines and activated alkynes with or without amine. This protocol provides an efficient platform to prepare a diverse range of unusual three-dimensional functionalized oxa-aza[4.3.3]propellane- and indoline-related scaffolds in a modular pattern, which can greatly expend the chemical space of [3,3]-sigmatropic rearrangements.