2-Bromobutanoyl chloride → 2-Bromo-1-(5-chlorobenzo[b]thiophen-2-yl)butan-1-one

A solution of 2-bromobutyryl chloride (8 g) in dichloromethane (15 ml) was added dropwise under nitrogen at ambient temperature to a stirred suspension of anhydrous aluminium chloride (12 g) in dichloromethane (100 ml). When the addition was complete, a solution of 5-chlorobenzo[b]thiophene (5 g; prepared in a manner similar to that described in J. Heterocyclic Chem., 1988, 25, 1271) in dichloromethane (30 ml) was added dropwise, then the mixture was stirred at ambient temperature for 1 hour and added to ice-cold water (500 ml). The mixture was stirred at ambient temperature for 30 minutes then the product was extracted into dichloromethane (100 ml). The extract was washed with water (2×30 ml) and saturated aqueous sodium chloride solution (2×30 ml), then it was dried (Na2SO4) and the solvent was removed in vacuo. The residue was purified by repeated (5-fold) flash chromatography over silica using a 19:1 mixture of petroleum ether (b.p. 60-80° C.) and ethyl acetate as eluant. Appropriate fractions were combined and the solvents removed in vacuo to give 2-bromo-1-(5-chlorobenzo[b]thiophen-2-yl)butan-1-one (1.04 g) as an off-white solid which was used without further purification.

1. additionWhen the addition
2. customprepared in a manner similar to
3. stirringThe mixture was stirred at ambient temperature for 30 minutes
4. extractionthe product was extracted into dichloromethane (100 ml)
5. washThe extract was washed with water (2×30 ml) and saturated aqueous sodium chloride solution (2×30 ml)
6. dry with materialit was dried (Na2SO4)
7. customthe solvent was removed in vacuo
8. customThe residue was purified
9. additiona 19:1 mixture of petroleum ether (b.p. 60-80° C.) and ethyl acetate as eluant
10. customthe solvents removed in vacuo

ORD record

ord-d77f16ad07264c6b992c6e4b5b4f6095

Source dataset

uspto-grants-2005_05

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06900216B2