Dimethylformamide → Methyl 5-(chlorocarbonyl)thiophene-2-carboxylate

Participants

Reaction Conditions

Reaction Steps

150 g (749 mmol) of dimethyl thiophene-2,5-dicarboxylate in 1350 mL of toluene was azeotropically distilled at 130° C. to evaporate 150 mL of it. The reaction solution was cooled to an inner temperature of 70° C., then stirred with 300 mL of 2.5 M potassium hydroxide/methanol for 40 minutes and cooled to room temperature, and the precipitated solid was washed with ethyl acetate by filtration and dried under reduced pressure to obtain 160 g of potassium 5-(methoxycarbonyl)-thiophene-2-carboxylate. 100 g (446 mmol) of potassium 5-(methoxycarbonyl)-thiophene-2-carboxylate in 700 mL of 1,2-dichloroethane was mixed with 1.73 mL of N,N-dimethylformamide and heated to 90° C., and 68.9 g (119 mmol) of thionyl chloride was added dropwise. The reaction solution was refluxed for 1 hour and then cooled to room temperature, and the resulting crystals were filtered off with 300 mL of 1,2-dichloroethane. The filtrate was concentrated to dryness to obtain 90.4 g (yield 99%) of methyl 5-(chlorocarbonyl)thiophene-2-carboxylate (TEC).

Provenance & Evidence