Ruthenium-Catalyzed Synthesis of Fused Tricyclic 1H‑2,3-Dihydropyrimido[1,2‑a]quinolines in One Step

A novel ruthenium-catalyzed intramolecular cyclization of a nitrile and an azetidine was developed to achieve a one-step synthesis of the fused tricyclic 1H-2,3-dihydropyrimido­[1,2-a]­quinoline, which is the core skeleton for more than 100 natural pyoverdines and is also responsible for their fluorescence.