Copper-catalyzed three-component synthesis of pyrrole-substituted 1,2-dihydroisoquinolines

A general approach to the synthesis of 1,3-disubstituted-1,2-dihydroisoquinolines was achieved with pyrrole and various electron withdrawing groups as substituents. CuAAC reaction on enynes yielded the resulting 1,2,3-triazole which spontaneously decomposed to the corresponding ketenimine. Nucleophilic attack by pyrrole and subsequent intramolecular Aza-Michael cyclization generated 1,2-dihydroisoquinolines in moderate to good yields. The optimized conditions allow for a range of substituents with excellent reproducibility.