An Improved Synthesis of 2-(Pyrid-2΄-Yl)-1,10-Phenanthroline Tridentate Terpyridyl Ligand

An improved multistep synthetic route for preparation of a tridentate terpyridyl ligand, 2-(pyrid-2΄-yl)-1,10-phenanthroline, has been reported. In the first step, a Skraup quinoline synthesis using m-toluidine and glycerol was employed. The mixture of 5- and 7-methylquinoline which was obtained was selectively nitrated at 8-carbon position of the 7- derivative. The methyl group in 7-methyl-8-nitroquinoline was then oxidized to an aldehyde followed by a reduction of the nitro group to an amine group. The last step involved a Friedlander condensation of the amino aldehyde with 2-acetylpyridine to obtain the final product with overall high yield. All products were fully characterized.