title: Palladium-catalyzed annulation of 1,2-diborylalkenes and -arenes with 1-bromo-2-[(Z)-2-bromoethenyl]arenes: a modular approach to multisubstituted naphthalenes and fused phenanthrenes.
abstract: (Z)-1,2-Diaryl-1,2-bis(pinacolatoboryl)ethenes underwent double-cross-coupling reactions with 1-bromo-2-[(Z)-2-bromoethenyl]arenes in the presence of [Pd(PPh(3))(4)] as a catalyst and 3 M aqueous Cs(2)CO(3) as a base in THF at 80 °C. The double-coupling reaction gave multisubstituted naphthalenes in good to high yields. Annulation of 1,2-bis(pinacolatoboryl)arenes with bromo(bromoethenyl)arenes in the presence of a catalyst system that consisted of [Pd(2)(dba)(3)] (dba=dibenzylideneacetone) and 2-dicyclohexylphosphino-2',6'-dimethoxybiphenyl (SPhos) under the same conditions produced fused phenanthrenes in good to high yields. The first annulation coupling occurred regiospecifically at the bromoethenyl moiety. This procedure is applicable to the facile synthesis of polysubstituted anthracenes, benzothiophenes, and dibenzoanthracenes through a double annulation pathway by using the corresponding dibromobis[(Z)-2-bromoethenyl]benzenes as diboryl coupling partners.
authors.affiliation: Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto University Katsura, Nishikyo-ku, Kyoto 615-8510, Japan. m.shimizu@hs2.ecs.kyoto-u.ac.jp
authors.forename: Masaki
authors.initials: M
authors.lastname: Shimizu
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Tomioka
authors.forename: Ikuhiro
authors.initials: I
authors.lastname: Nagao
authors.forename: Tsugumi
authors.initials: T
authors.lastname: Kadowaki
authors.forename: Tamejiro
authors.initials: T
authors.lastname: Hiyama
mesh_terms: D000475:Alkenes / Q000737:chemistry*; D001966:Bromine / Q000737:chemistry; D002384:Catalysis; D009281:Naphthalenes / Q000138:chemical synthesis* / Q000737:chemistry; D010165:Palladium / Q000737:chemistry*; D010616:Phenanthrenes / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D000475:Alkenes; D009281:Naphthalenes; D010616:Phenanthrenes; D010165:Palladium; D001966:Bromine