Palladium(0)-catalyzed tandem cyclization of allenenes: direct construction of tricyclic heterocycles through aromatic C--H activation.
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.
Ohno
Hiroaki
H
Graduate School of Pharmaceutical Sciences, Osaka University, Suita, Japan. hohno@phs.osaka-u.ac.jp
Miyamura
Kumiko
K
Mizutani
Tsuyoshi
T
Kadoh
Yoichi
Y
Takeoka
Yusuke
Y
Hamaguchi
Hisao
H
Tanaka
Tetsuaki
T
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
D000475:Alkenes; D006846:Hydrocarbons, Halogenated; D009942:Organometallic Compounds; D010165:Palladium