2-Amino-5-bromopyridine (13.8 g, 0.08 mol) and 2,5-hexanedione (14.1 mL, 0.12 mol) were dissolved in toluene (180 mL) and p-toluenesulfonic acid (100 mg) was added as catalyst. The reaction mixture was placed under reflux for 14 hours under a Dean-Stark apparatus. After completion of the reaction, it was cooled to room temperature and the brown reaction solution was poured into water (200 mL) and extracted with toluene (2 x 200 mL). The organic phases were combined, washed with brine (50 mL), dried with anhydrous magnesium sulfate, filtered and concentrated under reduced pressure to obtain the crude product. The crude product was purified by silica gel column chromatography with the eluent of ethyl acetate:pentane (1:3) to afford 5-bromo-2-(2,5-dimethyl-1H-pyrrol-1-yl)pyridine as a brown oil (18.4 g, 0.073 mol, 92% yield). The structure of the product was confirmed by 1H NMR (CDCl3, 400 MHz): δ 2.18 (s, 6H), 5.90 (s, 2H), 7.11 (d, 1H), 7.92 (d, 1H), 8.62 (s, 1H). Low resolution mass spectrometry (LRMS) shows m/z 253 ([M-H]+, Br isotope included).
