Dimethylformamide → 3,4-Diethyl-2-formylpyrrole

Participants

Reaction Steps

Dimethylformamide (DMF) (11.2 mL, 144.5 mmol) was cooled to 10° C. in an ice bath, and the purified phosphorous oxychloride (18.5 mL, 144.5 mmol) was added over 15 minutes, while maintaining the temperature between 10 and 20° C. The ice bath was removed and the solidified complex was allowed to warm to room temperature. Dichloroethane (10 mL) was added to the solid, which was heated to 30° C. to facilitate dissolution. The mixture was stirred for 10 minutes while additional dichloroethane (23 mL) was added, and the resulting solution was cooled in an ice bath. 3,4-Diethylpyrrole (16.2 g, 131.4 mmol) was dissolved in 33 mL of dichloroethane and added dropwise over the course of 30 minutes to the cooled solution, with vigorous stirring. The ice bath was then removed, and the solution was heated to reflux and stirred at reflux for 10 minutes, after which it was cooled to room temperature. Sodium acetate (64.9 g, 790.9 mmol) dissolved in deionized water (133 mL) was added to the resulting reaction mixture while maintaining the temperature of the reaction below 30° C. The resulting two-part mixture was heated to reflux while maintaining vigorous stirring. The mixture, which had become deep brown upon addition of pyrrole, now turned dark magenta. The mixture was stirred at reflux for 15 minutes. Upon cooling to room temperature, the mixture was separated, and the combined organic layers were washed (3×) with sodium bicarbonate solution (50 mL), dried, and filtered, and the solvent was removed under reduced pressure. The resulting oil was dried overnight under vacuum to give 3,4-diethyl-2-formylpyrrole, the compound of formula (2), in 70.9% yield.

Provenance & Evidence