5556-20-7

4892-02-8

5556-20-7

The general procedure for the synthesis of ethyl 3-hydroxybenzo[b]thiophene-2-carboxylate from methyl thiosalicylate was as follows: preparation of intermediate 6 (ethyl 3-hydroxybenzo[b]thiophene-2-carboxylate): methyl 2-mercaptobenzoate (1.63 mL, 11.9 mmol) and ethyl bromoacetate (1.32 mL, 11.9 mmol) were dissolved in anhydrous tetrahydrofuran (130 mL) and cooled to 0°C. Potassium tert-butoxide (5.14 g, 71.3 mmol) was slowly added to this solution over 2 min. The reaction mixture was stirred at 0 °C, followed by gradual warming to room temperature over 15 min. Upon completion of the reaction, the pH was adjusted to 2 with 2 M hydrochloric acid and diluted with 75 mL of water. The product was immediately extracted with ethyl acetate (3 x 75 mL). The organic layers were combined, washed with 75 mL of brine, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure to give a yellow solid product (2.32 g, 88% yield). The product was confirmed by nuclear magnetic resonance hydrogen spectroscopy (1H NMR): δ 10.21 (1H, s), 7.94 (1H), 7.74 (1H), 7.50 (1H), 7.41 (1H), 4.43 (2H), 1.43 (3H).