Iodine → 1-(1-Benzothiophen-5-yl)ethan-1-one

Approximately 1 ml of a solution of 5-bromobenzo[b]thiophene (6.6 g; prepared in a manner similar to that described in Example 21) in tetrahydrofuran (35 ml) was added under nitrogen to a mixture of magnesium turnings (0.8 g), tetrahydrofuran (7 ml) and a few small crystals of iodine, heat was applied to initiate the reaction, then the remainder of the bromobenzo[b]thiophene solution was added at reflux temperature over 20 minutes. When the addition was complete, the mixture was heated under reflux for 45 minutes, then a solution of N-methoxy-N-methylacetamide (3.8 g) in tetrahydrofuran (35 ml) was added. The mixture was heated under reflux for 30 minutes, cooled to ambient temperature, then quenched by the addition of 2M hydrochloric acid (90 ml) and stirred at ambient temperature for 30 minutes. The majority of the tetrahydrofuran was removed in vacuo, then water (150 ml) was added to the residue and the product was extracted into ethyl acetate (150 ml). The extract was washed with saturated aqueous sodium chloride solution (100 ml), dried (MgSO4) and the solvent removed in vacuo. The residue was purified by flash chromatography over silica using a 95:5 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 1-(benzo[b]thiophen-5-yl]ethan-1-one (2.35 g) as a white solid which was used without further purification.

1. customprepared in a manner similar to
2. customthe reaction
3. temperatureat reflux temperature over 20 minutes
4. additionWhen the addition
5. temperaturethe mixture was heated
6. temperatureunder reflux for 45 minutes
7. temperatureThe mixture was heated
8. temperatureunder reflux for 30 minutes
9. customquenched by the addition of 2M hydrochloric acid (90 ml)
10. customThe majority of the tetrahydrofuran was removed in vacuo
11. additionwater (150 ml) was added to the residue
12. extractionthe product was extracted into ethyl acetate (150 ml)
13. washThe extract was washed with saturated aqueous sodium chloride solution (100 ml)
14. dry with materialdried (MgSO4)
15. customthe solvent removed in vacuo
16. customThe residue was purified by flash chromatography over silica using
17. additiona 95:5 mixture of petroleum ether (b.p. 60-80° C.) and ethyl acetate as eluant
18. customthe solvents removed in vacuo

ORD record

ord-fb1f5b00ae9e4894be81aacae39a0edc

Source dataset

uspto-grants-2005_05

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06900216B2