Methanol → Methyl 4-bromo-5-methylthiothiophene-2-carboxylate

To a stirred solution of 4-bromo-5-methylthiothiophene-2-carboxylic acid (87 mmol), prepared according to the procedure of Kleemann, et al., EP 0676395A2, in dry methanol (750 mL) was added thionyl chloride (7 mL, 96 mmol) dropwise. After stirring for 10 min at room temperature, the solution was heated to reflux and stirred 7.5 h. The solution was cooled and the solvents were removed in vacuo. The resulting solid was dissolved in dichloromethane (1500 mL) and washed with saturated sodium bicarbonate (2×300 mL), water (300 mL), saturated brine (300 mL), and dried over anhydrous sodium sulfate. The solvents were removed in vacuo. The resulting solid was recrystallized twice from hexane/ethyl acetate to give methyl 4-bromo-5-methylthiothiophene-2-carboxylate (4.4 g, 19%). 1H-NMR (CDCl3, 400 MHz) δ7.66 (s, 1H), 3.90 (s, 3H), 2.60 (s, 3H).

1. temperaturethe solution was heated
2. temperatureto reflux
3. stirringstirred 7.5 h
4. temperatureThe solution was cooled
5. customthe solvents were removed in vacuo
6. dissolutionThe resulting solid was dissolved in dichloromethane (1500 mL)
7. washwashed with saturated sodium bicarbonate (2×300 mL), water (300 mL), saturated brine (300 mL)
8. dry with materialdried over anhydrous sodium sulfate
9. customThe solvents were removed in vacuo
10. customThe resulting solid was recrystallized twice from hexane/ethyl acetate

ORD record

ord-3739c46741e541eb9dd244d214705f6c

Source dataset

uspto-grants-2002_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06492403B1