反应详情

A mixture of crude 3-bromo-4-cyclopropyl-5-fluoro-4H-pyridine-1-carboxylic acid phenyl ester (A; 7.5 g, 0.022 mol) and sulphur (0.71 g, 0.022 mol) were heated at reflux in DECALIN (25 mL) for a period of 3 h and then cooled to RT. The reaction mixture was purified by silica gel column chromatography, eluting first with hexane and then with a 2-5% ethyl acetate-hexane gradient to afford 3-bromo-4-cyclopropyl-5-fluoro-pyridine. 1H NMR (400 MHz, DMSO-d6) δ 8.54 (s, 1H), 8.42 (s, 1H), 1.98-1.94 (m, 1H), 1.11-1.09 (m, 2H), 0.99-0.98 (m, 2H). MS (M+1): 217.1.

1. customThe reaction mixture was purified by silica gel column chromatography
2. washeluting first with hexane