Carbon Dioxide → thiophene-2,3-dicarboxylic acid

Participants

Reaction Conditions

Reaction Steps

A dry, 2 L, 3-necked, round-bottomed flask was equipped with a mechanical stirrer and addition funnel. To the flask was added 2-thiophenecarboxylic acid (25 g, 195 mmol) in anhydrous THF (500 mL) under argon. The mixture was cooled to −78° C. with a dry ice-isopropanol bath and allowed to stir for 30 min. n-Butyllithium in Hexanes (2.5 M, 172 mL) was added dropwise over 30 min. The reaction was kept at −78° C. for an additional hour with stirring then placed under an atmosphere of dry carbon dioxide. With addition of the carbon dioxide the reaction became thick. The reaction remained at −78° C. for an additional hour before warming to −10° C. The reaction was quenched with 2 N HCl (213 mL) and allowed to reach rt. The layers were separated and the aqueous layer was extracted with EtOAc (3×200 mL). The organic layers were combined, dried (Na2SO4) and concentrated by rotary evaporation. The brown solid was crystallized from hot isopropanol and dried overnight under vacuum. Desired thiophene-2,3-dicarboxylic acid was obtained (27.3 g, 159 mmol; 82% yield); 1H NMR (DMSO-d6) 7.69 (d, J=1.5, 1), 7.38 (d, J=4.8, 1); ES MS (M+H)+=173; TLC (Chloroform-MeOH-water, 6:4:1); Rf=0.74.

Provenance & Evidence