Dimethylformamide → 5-Fluoro-7-benzofurancarboxaldehyde

Participants

Reaction Conditions

Reaction Steps

7-Bromo-5-fluoro-benzofuran (7 g, 32 mmol, Step B) was dissolved in a mixture of tetrahydrofuran (350 mL) and pentane (100 mL), cooled to −95 to −100° C., and treated with n-butyl lithium (14 mL, 35 mmol, 2.5M in hexane, Aldrich). After stirring for 5 minutes, a solution of dimethylformamide (5 mL) in tetrahydrofuran (15 mL) was added dropwise and the reaction temperature raised to −20° C. This was treated with aqueous ammonium chloride (50 mL) and stirred for 0.5 hour at ambient temperature. The reaction mixture was concentrated in vacuo and diluted with hexane. The organic fraction was washed with water and dried (Na2SO4). Removal of solvent afforded crude 5-fluoro-benzofuran-7-carbaldehyde (˜30%) as an oil. Purification was by silica gel chromatography (5-10% ethyl ether/hexane). HRMS, observed: 163.0201; Calcd for (M+H)+: 163.0195

Provenance & Evidence