Dehydroaromatization of Quinoxalines: One-Step Syntheses of Trinuclear 1,6,7,12,13,18-Hexaazatrinaphthylene Titanium Complexes

We report the spontaneous coupling of N-heterocycles, initiated by C−H bond activation reactions. The reaction of quinoxalines and the titanocene acetylene complex Cp2Ti{η2-C2(SiMe3)2}, as an excellent titanocene source, results in the formation of trinuclear 1,6,7,12,13,18-hexaazatrinaphthylene (HATN) titanium complexes. These HATN titanium complexes are thermally stable but sensitive to air and moisture. A three-fold dehydrogenative C−C coupling is proposed as the main step in the presented synthetic procedure. Particularly using commercial starting materials, an efficient route for the dehydrogenative coupling of N-heterocycles, leading to multidentate ligands, has been established.