Formal nitrogen-to-carbon replacement in isoindolines to form indenes via N-alkyl tetrahydroisoquinolines

Abstract

Herein, we report a Stevens rearrangement ring expansion of isoindolines to N-alkyl-2-aroyl-tetrahydroisoquinolines, followed by a photochemical nitrogen atom extruding ring contraction and elimination to give indene derivatives. By combining the ring expansion and ring contraction in a one-pot procedure, a net single-atom nitrogen-to-carbon replacement was realized. Factors that guide the stability of the immediate amino-indane products that are formed through photochemical ring contraction were studied. Reaction of the amino-indane intermediates with anhydrides yielded stable and isolable functionalized amino indane derivatives in some cases.