5-Bromo-2-methyl-thiophene-3-carboxylic acid synthesis

Yield:1344027-40-2 84%

Reaction Conditions:

with acetic acid;pyridinium hydrobromide perbromide at 40; for 4 h;Inert atmosphere;

Steps:

4.2.7. Synthesis of 5-bromo-2-methylthiophene-3-carboxylic acid (8)

To a solution of 2-methylthiophene-3-carboxylic acid (2.44 g, 17.2 mmol, prepared from commercially available thiophene-3-carboxylic acid according to the known procedure (US 5840917 A1)) was added pyridium tribromide (6.3 g) in AcOH (30 mL) at room temperature. The mixture was stirred at 40 °C for 4 h. The mixture was cooled to room temperature and poured into H₂O (350 mL) with stirring. The product was precipitated and the suspension was stirred at room temperature for 1 h. The precipitated solid was filtered, washed with H₂O (500 mL) and dried under high vacuum at 45 °C. The crude product was used without further purification (3.18 g, 84%). ¹H NMR (400 MHz, CDCl₃) δ 7.38 (s, 1H), 2.70 (s, 3H); MS calcd for C₆H₅BrO₂S (MW 221.07), found [M+H]⁺ 221.

References:

Lee, Suk Ho;Song, Kwang-Seop;Kim, Jong Yup;Kang, Misuk;Lee, Jun Sung;Cho, Seung-Hwan;Park, Hyun-Ju;Kim, Jeongmin;Lee, Jinhwa [Bioorganic and Medicinal Chemistry,2011,vol. 19,# 19,p. 5813 - 5832] Location in patent:experimental part