Hydrochloric Acid → Ethyl 3-Methyl-4-methoxy-7-(2-thienoyl)benzofuran-2-carboxylate

Participants

Reaction Steps

To a solution of ethyl 3-methyl-4-methoxy-benzofuran-2-carboxylate (3.48 g, 14.86 mmol) in dry 1,2-dichloroethane (15 mL) was added a solution of thiophene-2-carbonyl chloride (6.54 g, 44.61 mmol) in 1,2-dichloroethane (10 mL) followed by the portionwise addition of aluminum chloride (7.92 g, 59.40 mmol). An exothermic reaction ensued and the mixture was allowed to stir until gas evolution had slowed, then warmed to reflux for 2 hours. Upon cooling the reaction mixture was poured into 2N HCl (100 mL) and extracted with methylene chloride (4×25 mL). The combined organic extracts were washed with 5% NaHCO3, dried (Na2SO4), and concentrated to a brown solid (5.40 g). Recrystallization from ethanol/benzene afforded pure ethyl 3-methyl-4-methoxy-7-(2-thienoyl)benzofuran-2-carboxylate, compound 1. mp 179°-182° C.; 1H NMR d 1.40 (3H, t, J=6 Hz), 2.77 (3H, s), 4.04 (3H, s), 4.42 (2H, q, J=6 Hz), 6.75 (1H, d, J=8 Hz), 7.17 (1H, dd, J=4 Hz), 7.72 (2H, m), 7.86 (1H, d, J=8 Hz).

Provenance & Evidence