4,5,6,7-Tetrahydro-4-oxothionaphthene → Benzo(b)thiophen-4-ol

Phenyltrimethylammonium tribromide (11.4 g) was added in portions under nitrogen at ambient temperature over 35 minutes to a stirred solution of 6,7-dihydrobenzo[b]thiophen-4(5H)-one (4.6 g) in tetrahydrofuran (45 ml), the mixture was stirred for 1 hour and allowed to stand at ambient temperature overnight, then it was filtered and the solvent was removed in vacuo. The residue was dissolved in dimethylformamide (20 ml), the solution was added under nitrogen to a suspension of lithium carbonate (8.2 g) in dimethylformamide (50 ml), the mixture was heated under reflux for 4 hours, then it was cooled to ambient temperature and added to 10% aqueous acetic acid solution (500 ml). The product was extracted into dichloromethane (3×100 ml) and the combined extracts were washed with water (3×100 ml), dried (MgSO4), and the solvent was removed in vacuo. The residue was purified by flash chromatography over silica using dichloromethane as eluant. Appropriate fractions were combined and the solvents removed in vacuo to give benzo[b]thiophen-4-ol (4 g) as a white solid which was used without further purification.

1. waitto stand at ambient temperature overnight
2. filtrationit was filtered
3. customthe solvent was removed in vacuo
4. dissolutionThe residue was dissolved in dimethylformamide (20 ml)
5. additionthe solution was added under nitrogen to a suspension of lithium carbonate (8.2 g) in dimethylformamide (50 ml)
6. temperaturethe mixture was heated
7. temperatureunder reflux for 4 hours
8. additionadded to 10% aqueous acetic acid solution (500 ml)
9. extractionThe product was extracted into dichloromethane (3×100 ml)
10. washthe combined extracts were washed with water (3×100 ml)
11. dry with materialdried (MgSO4)
12. customthe solvent was removed in vacuo
13. customThe residue was purified by flash chromatography over silica
14. customthe solvents removed in vacuo

ORD record

ord-05e31ade46f243a6a73b9f724c6c836a

Source dataset

uspto-grants-2005_05

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06900216B2