To a solution of 6-bromoindazole-3-carboxylic acid (4.4 g, 18.25 mmol) in ethanol (100 mL) was slowly added thionyl chloride (666 mL, 91 mmol), followed by heating and refluxing the reaction mixture for 3 hours. Upon completion of the reaction, the reaction mixture was concentrated under reduced pressure and purified by fast column chromatography to afford ethyl 6-bromo-1H-indazole-3-carboxylate (2.1 g, 39% yield) as a tan solid. Mass spectrum (ESI) m/z: 270.9 (M + H). NMR hydrogen spectrum (400MHz, CDCl3) δ 8.08 (d, J = 8.6Hz, 1H), 7.95 (s, 1H), 7.44 (d, J = 8.6Hz, 1H), 4.57 (q, J = 7.0Hz, 2H), 1.51 (t, J = 7.2Hz, 3H).
