Methanol → Methyl 4-bromothiophene-2-carboxylate

Participants

Reaction Steps

To a cooled (−20° C.) solution of 6.02 g (29.1 mmol) of 4-bromothiophene-2-carboxylic acid (as prepared in the previous step) in 100 mL of anhyd MeOH under nitrogen was added 2.55 mL (34.9 mmol) of thionyl chloride dropwise at a rate to keep the temperature below −5° C. (ca. 8-10 min). After stirring for 1 h at room temperature, the mixture was refluxed for 8 h, cooled, and concentrated in vacuo. The resulting 6.7 g of pale amber oil was passed through a 150 g pad of silica gel with ca. 600 mL of CH2Cl2 (discarding the first 120 mL which contained a minor impurity) to afford, after concentration in vacuo, the title compound as a colorless oil (6.11 g, 95%). 1H-NMR (300 MHz, CDCl3) δ7.69 (d, 1H, J=1.5 Hz), 7.45 (d, 1H, J=1.5 Hz), and 3.90 (s, 3H).

Provenance & Evidence