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We have synthesized a range of novel cyclometallated organoruthenium(II) complexes through ortho-C-H activation of the aryl group in 2-aryl-substituted quinazolines with [RuX2(p-cymene)]2. The beneficial effect of the carboxylate ligand on both the cyclometallation and further arylation reaction step was demonstrated. Mechanistic studies reveal that bromide and iodide anions decelerates the arylation process via in situ ligand exchange reaction. Additionally, a detailed NMR investigation explains some elementary steps in the arylation of 2-(aryl)quinazoline-halido-ruthenacycles.

A series of coupling products have been prepared by a ruthenium(II)-catalyzed direct ortho-C–H arylation of 2-(aryl/heteroaryl)-substituted quinazolines with (hetero)aryl bromides. Tri(hetero)aryl-substituted alkenes were also prepared by olefinic C–H activation of 2-(2-arylvinyl)quinazoline derivatives. High conversions and selectivities were achieved by choosing the appropriate ruthenium(II) carboxylate catalyst system, solvent, and reaction temperature. The possibility of a C(sp3)–H functionalization by applying an arylation/reduction reaction sequence was also demonstrated.