Mixed Directing-Group Strategy: Oxidative C-H/C-H Bond Arylation of Unactivated Arenes by Cobalt Catalysis
Cong Du1, Peng-Xiang Li1, Xinju Zhu1
1College of Chemistry and Molecular Engineering, Zhengzhou University, Kexue avenue 100, Zhengzhou, P.R. China.
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.
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