Efficient access to quinolines and quinazolines by ruthenium complexes catalyzed acceptorless dehydrogenative coupling of 2-aminoarylmethanols with ketones and nitriles

Treatment of N,N,O-tridentate pyrazolyl-pyridinyl-alcohol ligands, 2-((CRROH)-R-1-O-2)-6-[3,5-(R-3)(2)C3HN2]C5H3N (R-1 = R-2 = Me, R-3 = H (L1H); R-1 = Me, R-2 = Ph, R-3 = H (L2H); R-1 = R-2 = Ph, R-3 = H (L3H); R-1 = R-2 = R-3 = Me (L4H)) with RuCl3.xH(2)O in refluxing EtOH afforded the corresponding Ru(III) complexes L2RuCl (1a-1d), which were well characterized by IR, HR-MS and X-ray single crystal structural determination. These Ru complexes showed similarly high catalytic performance for both dehydrogenative couplings of 2-aminoarylmethanols with ketones and nitriles, giving the quinolines and quinazolines in good to excellent yields. This protocol provides an atom-economical and sustainable route to access various structurally important quinoline and quinazoline derivatives by using phosphine-free ligand based Ru catalysts.

Automated summary

Treatment of N,N,O-tridentate pyrazolyl-pyridinyl-alcohol ligands with RuCl3.xH(2)O in refluxing EtOH afforded Ru(III) complexes, which showed high catalytic performance for dehydrogenative couplings of 2-aminoarylmethanols with ketones and nitriles, providing a sustainable route to access various structurally important quinoline and quinazoline derivatives.