5-Bromobenzo[b]thiophene

white solid

5-Bromobenzo[b]thiophene is used as a reactant in the preparation of 4-aminoquinolines and tetraoxanes displaying antimalarial activity.

Journal of Heterocyclic Chemistry, 25, p. 1271, 1988 DOI: 10.1002/jhet.5570250445

A mixture of phosphoric acid (218 g) and chlorobenzene (2 L) was heated at 130C and then treated with the product from Example 165A (107.0 g) for 2 hours using a syringe pump. The mixture was heated at 130C for 15 hours. Water was removed from the mixture using a Dean-Stark trap at the start of reflux. The mixture was cooled to room temperature and quenched with 400 mL of water. The bottom aqueous layer was extracted with 200 mL of dichloromethane. The combined organic layers were washed with 200 mL of 10% Na2CO3 and concentrated to a brown oil (129.4 g). The crude oil was dissolved in 1 L of 10:90 EtOAC:hexane, filtered through a short pad of silica gel and concentrated. Further purification by column chromatography (silica gel, 5:95EtOAc:hexane) afforded 5-bromobenzo[b]thiophene yellow oil in yield (85.54 g, 95.8%).