title: Palladium(0)-catalyzed tandem cyclization of allenenes: direct construction of tricyclic heterocycles through aromatic C--H activation.
abstract: Palladium(0)-catalyzed tandem cyclization of allenenes is described. Treatment of allenenes with an aryl halide, potassium carbonate, and catalytic [Pd(PPh(3))(4)] in dioxane afforded tri- or tetracyclic heterocycles in moderate to good yields through insertion of arylpalladium(II) halide into the allenic moiety, intramolecular carbopalladation, and aromatic C--H bond activation. The substituent on the olefin terminus has proven to be essential for the success of the tandem cyclization. The reaction with heterocyclic aryl halides such as iodopyrazine or 4-bromo-1-methylindole afforded tri- or tetracyclic heteroaromatic products in good yields.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Osaka University, Suita, Japan. hohno@phs.osaka-u.ac.jp
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Ohno
authors.forename: Kumiko
authors.initials: K
authors.lastname: Miyamura
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Mizutani
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Kadoh
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Takeoka
authors.forename: Hisao
authors.initials: H
authors.lastname: Hamaguchi
authors.forename: Tetsuaki
authors.initials: T
authors.lastname: Tanaka
mesh_terms: D000475:Alkenes / Q000138:chemical synthesis* / Q000737:chemistry; D002384:Catalysis; D003500:Cyclization; D006846:Hydrocarbons, Halogenated / Q000138:chemical synthesis / Q000737:chemistry*; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D010165:Palladium / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D000475:Alkenes; D006846:Hydrocarbons, Halogenated; D009942:Organometallic Compounds; D010165:Palladium