General procedure for the synthesis of 5-bromomethylpyridine-2-carboxylic acid methyl ester from 5-methylpyridine-2-carboxylic acid: in a 500 mL round bottom flask, N-bromosuccinimide (NBS, 14.13 g, 79.38 mmol, 1.20 eq.) and azobisisobutyronitrile (AIBN, 217 mg, 1.32 mmol, 0.02 eq.) were added to a 5- methyl pyridine-2-carboxylate (10 g, 66.15 mmol, 1.00 equiv) in a solution of carbon tetrachloride (CCl4, 200 mL). The reaction mixture was stirred at 80 °C for 16 hours. After completion of the reaction, the mixture was concentrated under reduced pressure. The residue was purified by silica gel column chromatography using ethyl acetate/petroleum ether (5% to 25% gradient) as eluent to afford methyl 5-bromomethylpyridine-2-carboxylate (9.6 g, 57% yield) as a yellow solid. Mass spectrum (MS): m/z = 229.9 [M + H]+.
