Regioselective Direct C-H Trifluoromethylation of Pyridine
Xiao Yang1, Rui Sun1, Shun Li1
1Key Laboratory of Green Chemistry & Technology, Ministry of Education College of Chemistry, Sichuan University, Chengdu 610064, P. R. China.
Abstract:
A highly efficient and regioselective direct C-H trifluoromethylation of pyridine based on an N-methylpyridine quaternary ammonium activation strategy has been developed. A variety of trifluoromethylpyridines can be obtained in good yield and excellent regioselectivity by treating the pyridinium iodide salts with trifluoroacetic acid in the presence of silver carbonate in N,N-dimethylformamide. The protocol features good functional group compatibility, easily available starting materials, and operational simplicity. Controlled experiments showed that the reaction may involve a nucleophilic trifluoromethylation mechanism.
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