RHODIUM-CATALYZED SYNTHESIS OF PYRIDINES FROM ALKYNES AND NITRILES

Complexes of general formula left bracket RhCpL//2 right bracket , (I), are excellent long-lived catalyst precursors for the synthesis of pyridine derivatives by cocyclization of alkynes and nitriles, at temperatures between 100 and 170 degree C. The activity of the catalyst precursors (I) depends upon the nature of both Cp and L ligands, being highest when Cp equals C//5H//5 and L equals C//2H//4, and is not depressed by the presence of various functional groups in the substrates. The concurrent formation of benzene derivatives from alkyne self-trimerization can be strongly reduced by using nitrile-to-alkyne molar ratios higher than 5.