We serendipitously found an unprecedented 5-to-7-membered ringexpansion of 2-alkylspiroindolenines to azepinoindoles mediated by n-tetrabutylammonium fluoride. The starting materials can be easily prepared by the hypoiodite-catalyzed oxidative dearomative spirocyclization of indole derivatives. Mildly basic conditions and electron-deficient protecting groups for the amines were found to be crucial