title: A combined experimental and computational study on the cycloisomerization of 2-ethynylbiaryls catalyzed by dicationic arene ruthenium complexes.
abstract: Ruthenium-catalyzed cycloisomerization of 2-ethynylbiaryls was investigated to identify an optimal ruthenium catalyst system. A combination of [η(6) -(p-cymene)RuCl2 (PR3 )] and two equivalents of AgPF6 effectively converted 2-ethynylbiphenyls into phenanthrenes in chlorobenzene at 120 °C over 20 h. Moreover, 2-ethynylheterobiaryls were found to be favorable substrates for this ruthenium catalysis, thus achieving the cycloisomerization of previously unused heterocyclic substrates. Moreover, several control experiments and DFT calculations of model complexes were performed to propose a plausible reaction mechanism.
authors.affiliation: Department of Basic Medicinal Sciences, Graduate School of Pharmaceutical Sciences, Nagoya University, Chikusa, Nagoya 464-8601 (Japan). yamamoto-yoshi@ps.nagoya-u.ac.jp.
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: Kazuma
authors.initials: K
authors.lastname: Matsui
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Shibuya
mesh_terms: D001713:Biphenyl Compounds / Q000737:chemistry*; D002384:Catalysis; D056831:Coordination Complexes / Q000737:chemistry*; D000081007:Cymenes; D007536:Isomerism; D039821:Monoterpenes / Q000737:chemistry*; D010616:Phenanthrenes / Q000737:chemistry*; D012428:Ruthenium / Q000737:chemistry*
chemical_list: D001713:Biphenyl Compounds; D056831:Coordination Complexes; D000081007:Cymenes; D039821:Monoterpenes; D010616:Phenanthrenes; C007210:4-cymene; C023626:4-ethynylbiphenyl; D012428:Ruthenium
keywords: cycloisomerization; ethynylbiaryls; heterocycles; phenantherenes; ruthenium catalyst