General procedure for the synthesis of 2-bromo-3-(trifluoromethoxy)pyridine: 2-chloro-3-trifluoromethoxypyridine (8, 4.0 g, 20.2 mmol) was used as a raw material and mixed with bromotrimethylsilane (6.3 g, 5.4 mL, 40.4 mmol, 2 eq.) in propionitrile (20 mL) and heated and refluxed for 24 hours. The reaction process was monitored by gas chromatography (GC) to confirm 100% conversion. Upon completion of the reaction, the mixture was vacuum distilled to afford pure 2-bromo-3-trifluoromethoxypyridine (23, 3.9 g, 16.1 mmol, 80% yield) as a colorless oil. Boiling point: 63-67 °C/13 mbar. The structure of the product was confirmed by nuclear magnetic resonance hydrogen (1H NMR, CDCl3, 300 MHz), fluorine (19F NMR, CDCl3, 282 MHz), and carbon (13C NMR, CDCl3, 75 MHz) spectra, and is consistent with the expected structure. Elemental analysis results: C6H3BrF3NO (molecular weight 241) Calculated values: C 29.78, H 1.25, N 5.79; measured values: C 29.96, H 1.41, N 5.64.
