Catalyst- and Additive-Free Annulation of Ynediones and (Iso)Quinoline -Oxides: An Approach to Synthesis of Pyrrolo[2,1-]Isoquinolines and Pyrrolo[1,2-]Quinolines.

A simple and effective annulation of ynediones and (iso)quinoline -oxides was developed to afford various functionalized pyrrolo[2,1-]isoquinolines and pyrrolo[1,2-]quinolines in moderate to excellent yields. This protocol underwent a tandem [3 + 2] cycloaddition/ring-opening/-nucleophilic addition, which exhibited high regioselectivity, broad substrate tolerance, and atom economy under catalyst-, additive-free, and air conditions. Moreover, indolizine was also successfully prepared using pyridine -oxide.