6386-80-7

17347-32-9

68-12-2

6386-80-7

Magnesium shavings (257 mg, 10.6 mmol) were suspended in anhydrous tetrahydrofuran (THF, 1.7 mL) in a 25 mL three-neck flask and heated to reflux. A solution of 6-bromobenzo[b]thiophene (1.5 g, 7.04 mmol) in anhydrous THF (8.3 mL) was added slowly and dropwise. The reaction mixture was refluxed for 2 h and then cooled to 0°C. Subsequently, N,N-dimethylformamide (1.03 g, 1.09 mL, 14.1 mmol) was slowly added dropwise and the reaction system was allowed to warm up to room temperature naturally. The resulting green suspension was stirred overnight and concentrated. The residue was purified by silica gel column chromatography. The target fraction was collected and dried under vacuum to give benzo[b]thiophene-6-carbaldehyde (821 mg, 72% yield) as a yellow oil.