Benzo[b]thiophene-2-carboxylic acid, 7-bromo-

Synthesis

General procedure for the synthesis of 7-bromobenzo[b]thiophene-2-carboxylic acid from methyl 7-bromobenzo[b]thiophene-2-carboxylate: 7-bromobenzo[b]thiophene-2-carboxylic acid methyl ester (64 mg, 0.22 mmol) was dissolved in methanol (3 mL), followed by addition of 3 N sodium hydroxide solution (240 μL, 0.72 mmol). The reaction mixture was heated to reflux for 2 hours. Upon completion of the reaction, the reaction mixture was acidified with 3 N hydrochloric acid and extracted with ethyl acetate (30 mL). The organic phases were combined, dried over anhydrous sodium sulfate (Na2SO4) and concentrated under reduced pressure. 7-Bromobenzo[b]thiophene-2-carboxylic acid (62 mg, 0.24 mmol, 100% yield) was obtained as a white solid and did not require further purification by silica gel column chromatography.

References

[1] Patent: KR2015/117318, 2015, A. Location in patent: Paragraph 0181; 0192; 0193; 0194
[2] European Journal of Medicinal Chemistry, 2017, vol. 125, p. 538 - 550
[3] Patent: WO2003/104227, 2003, A1. Location in patent: Page 47, 48
[4] Patent: EP2926660, 2015, A1. Location in patent: Paragraph 0262; 0263