Metal‐Free Cascade Annulation Approach for Modular Assembly of Alkynyl/Benzoyl Functionalized Quinolines

A concise and efficient synthetic method for alkynyl quinolines through TfOH‐promoted cascade 1,4‐conjugate addition/intramolecular annulation/aromatization process is established. By virtue of reactive aza‐o‐AQM (in situ generated from modular propargylamine), this reaction proceeds smoothly to afford a variety of alkynyl quinolines in good to excellent yields. This transition‐metal‐free process features halogen groups tolerance, such as the −Cl, −Br, and −I groups; thus, this protocol circumvents the inherent shortcomings of the existing Sonogashira coupling of halogenated quinolines.