title: Mixed Directing-Group Strategy: Oxidative C-H/C-H Bond Arylation of Unactivated Arenes by Cobalt Catalysis.
abstract: A mixed directing-group strategy for inexpensive [Co(acac)3]-catalyzed oxidative C-H/C-H bond arylation of unactivated arenes has been disclosed. This strategy enables the arylation of a wide range of benzamide and arylpyridines effectively to afford novel bifunctionalized biaryls, which are difficult to achieve by common synthetic routes. Two different pathways, namely, a single-electron-transmetalation process (8-aminoquinoline-directed) and a concerted metalation-deprotonation process (pyridine-directed), were involved to activate two different inert aromatic C-H bonds. Moreover, the aryl radicals have been trapped by 2,6-di-tert-butyl-4-methylphenol to form benzylated products. This unique strategy should be useful in the design of other arene C-H/C-H cross-couplings as well.
authors.affiliation: College of Chemistry and Molecular Engineering, Zhengzhou University, Kexue avenue 100, Zhengzhou, P.R. China.
authors.forename: Cong
authors.initials: C
authors.lastname: Du
authors.affiliation: College of Chemistry and Molecular Engineering, Zhengzhou University, Kexue avenue 100, Zhengzhou, P.R. China.
authors.forename: Peng-Xiang
authors.initials: PX
authors.lastname: Li
authors.affiliation: College of Chemistry and Molecular Engineering, Zhengzhou University, Kexue avenue 100, Zhengzhou, P.R. China.
authors.forename: Xinju
authors.initials: X
authors.lastname: Zhu
authors.affiliation: College of Chemistry and Molecular Engineering, Zhengzhou University, Kexue avenue 100, Zhengzhou, P.R. China.
authors.forename: Jian-Feng
authors.initials: JF
authors.lastname: Suo
authors.affiliation: College of Chemistry and Molecular Engineering, Zhengzhou University, Kexue avenue 100, Zhengzhou, P.R. China. niujunlong@zzu.edu.cn.
authors.forename: Jun-Long
authors.initials: JL
authors.lastname: Niu
authors.affiliation: College of Chemistry and Molecular Engineering, Zhengzhou University, Kexue avenue 100, Zhengzhou, P.R. China. mpsong@zzu.edu.cn.
authors.forename: Mao-Ping
authors.initials: MP
authors.lastname: Song
keywords: arylation; biaryls; cobalt; cross-coupling; reaction mechanisms