Ruthenium-catalyzed synthesis of quinolines from anilines and N-allylic compounds by cascade amine exchange reaction-heteroannulation

Anilines react with N-allylic compounds such as triallylamine and N,N-diallylaniline in dioxane in the presence of a catalytic amount of ruthenium(III) chloride hydrate and bis(diphenylphosphino)methane and tin(II) chloride dihydrate to afford the corresponding quinolines in high yields. Several other phosphorus ligands are also effective, but bis(diphenylphosphino)methane is the ligand of choice. A reaction path way involving cascade amine exchange reaction-heteroannulation is proposed for this catalytic process.