Synthesis of eight-membered hydroquinolines related to alkaloid skeletons via addition of 4-hydroxycoumarin or 4-hydroxypyran-2-one to quinolinium salts

A new one-pot synthesis of hitherto unknown polyheterocyclic systems via tandem C-alkylation and intramolecular O-alkylation of 4-hydroxycoumarin or 4-hydroxypyran-2-one with quinolinium salts in excellent yields (71–89%) is reported. The present approach provides a powerful route into polycyclic structures containing nitrogen and oxygen related to alkaloids.