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Ruthenium‐Catalyzed meta ‐Selective C−H Mono‐ and Difluoromethylation of Arenes through ortho ‐Metalation Strategy
Author(s) -
Li ZhongYuan,
Li Liang,
Li QiLi,
Jing Kun,
Xu Hui,
Wang GuanWu
Publication year - 2017
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201700354
Subject(s) - ruthenium , catalysis , chemistry , combinatorial chemistry , palladium , metalation , catalytic cycle , ligand (biochemistry) , substrate (aquarium) , functional group , medicinal chemistry , organic chemistry , receptor , biochemistry , oceanography , polymer , geology
The first example for the ruthenium‐catalyzed ligand‐directed meta ‐selective C−H mono‐ and difluoromethylation is developed, affording a variety of new meta ‐mono‐ and difluoromethylated 2‐phenylpyridines, 2‐phenylpyrimidines, and 1‐phenylpyrazoles in moderate‐to‐good yields. This new transformation exhibits broad substrate scope, good functional group tolerance, and high efficiency, and offers a practical approach to synthesize mono‐ and difluoromethylated arenes. Mechanistic studies indicate that a reaction pathway involving palladium‐initiated radical species is involved in the catalytic cycle. The new dual catalytic system consisting of compatible ruthenium(II) and palladium(0) complexes enables the key processes of C−H activation and mono‐/difluoromethyl‐radical formation to occur and achieves the meta ‐selective functionalization efficiently. In addition, the present protocol can also be extended to non‐fluoromethylation.