Azobisisobutyronitrile → Ethyl 5-(bromomethyl)-1-benzofuran-2-carboxylate

Participants

Reaction Steps

A mixture of the ester 25 (2.26 g, 11.1 mmol), JV-bromosuccinimide (2.37 g, 13.3 mmol) and VAZO (271 mg, 1.11 mmol) was refluxed overnight in CCl4 (50 mL) under nitrogen. The reaction mixture was cooled to the room temperature, diluted with dichloromethane and washed with water. The organic layer was dried over anhydrous MgSO4 and concentrated in vacuum. The residue was purified by flash chromatography (eluent 5% EtOAc in hexane) to give ethyl 5-bromomethyl-benzofuran-2-carboxylate. This compound was dissolved in dioxane (20 ml) and a solution of NaHCO3 (1.76 g, 20.9 mmol) in water (20 ml) was added. The reaction was stirred at 80° C. during 16 h. The solvent was evaporated and the product was dissolved in EtOAc and washed with brine. The organic layer was dried over anhydrous MgSO4 and concentrated in vacuum. The residue was purified by flash chromatography (eluent 20-40% EtOAc in hexane to give the title compound 26 (2.55 g, 61%) as a white solid. 1H-NMR (DMSO) δ: 7.74 (d, J=1.0 Hz, 1H), 7.71-7.70 (m, 1H), 7.65 (d, J=8.6 Hz, 1H), 7.44 (dd, J=8.6, 1.8 Hz, 1H), 5.31 (t, J=5.8 Hz, 1H), 4.59 (d, J=5.7 Hz, 2H), 4.35 (q, J=7.1 Hz, 2H); 1.34 (t, J=7.0, 3H).

Provenance & Evidence