Potassium t‐Butoxide‐Promoted Metal‐Free Synthesis of Pyrazino[1,2‐a]indoles via Direct Amidation and Intramolecular Hydroamination Reaction

Abstract A library of pyrazino[1,2‐ a ]indoles has been synthesized via direct amidation and alkyne hydroamination reactions of the molecule produced by indole‐2‐carboxylic acid and propargyl bromide. The noteworthy features of the present strategy are short reaction time, excellent yields and a broad substrate scope. This cascade reaction also occurred under transition metal‐free and ambient conditions as well as operational simplicity.