A Concise Protocol for the Synthesis of 2-Alkenylindoles through [4+1] Annulation of Aminobenzyl Phosphonium Salts with Acrylaldehydes

A concise and efficient protocol for the synthesis of various 2-alkenylindole derivatives is developed through [4 + 1] annulation starting from aminobenzyl phosphonium salts and cinnamaldehydes.