Dimethylformamide → 3-Methoxythiophene-2-carbaldehyde

1.03 ml of 3-methoxythiophene were dissolved in 2.3 ml of dimethylformamide. While cooling in ice, 1.06 ml of phosphoryl chloride were added. After 1 h, the reaction solution was added to ice, and the solution was neutralized with 5 molar sodium hydroxide solution. The aqueous phase was extracted 3 times with 25 ml of diethyl ether each time, and the combined organic phases were then washed with 50 ml of saturated sodium chloride solution, dried over sodium sulfate and concentrated. 840 mg of the product with the molecular mass of 142.18 (C6H7O2S) were obtained. MS (ESI): 143.0 (M+H+).