title: Iridium-catalyzed annulative coupling of 2-arylbenzoyl chlorides with alkynes: selective formation of phenanthrene derivatives.
abstract: 2-Arylbenzoyl chlorides undergo annulative coupling with internal alkynes in the presence of a catalyst system of [IrCl(cod)]2/P(t-Bu)3 to selectively afford the corresponding phenanthrene derivatives accompanied by elimination of carbon monoxide and hydrogen chloride. The reaction occurs without addition of any external base. Deuterium-labeling experiments using 2-(d5-phenyl)benzoyl chloride suggest that the rate-determining step does not involve the C2'-H bond cleavage. Formation of a [(t-Bu)3PH][(biphenyl-2,2'-diyl)Ir(CO)Cl2] complex dimer, of which the structure was determined by single-crystal X-ray analysis, from a stoichiometric reaction at 60 °C without addition of alkyne also supports the facile C-H cleavage.
authors.affiliation: Department of Applied Chemistry, Faculty of Engineering, Osaka University , Suita, Osaka 565-0871, Japan.
authors.forename: Tomoya
authors.initials: T
authors.lastname: Nagata
authors.forename: Koji
authors.initials: K
authors.lastname: Hirano
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Satoh
authors.forename: Masahiro
authors.initials: M
authors.lastname: Miura