Redox-triggered dearomative [5 + 1] annulation of indoles with <i>O</i>-alkyl <i>ortho</i>-oxybenzaldehydes for the synthesis of spirochromanes

Abstract

The dearomative [5 + 1] annulation of 2-methylindoles with new five-membered synthon was developed through cascade [1,5]-hydride transfer/dearomative cyclization in HFIP for the synthesis of spirochromanes bearing the 2-methylindolenine skeleton.