Oxygen → 4-Hydroxydibenzothiophene

Temperature

-78 °C

To a cooled (−78° C.) solution of dibenzothiophene (20.8 g, 113 mmol) in anhydrous THF (400 ml) was added tert-butyl lithium (1.7 M in pentane; 100 ml, 170 mmol). The reaction mixture was stirred at −78° C. for 1 hour and then allowed to warm to room temperature and stirred like this for 16 hours. The mixture was then cooled to 0° C. and ethylmagnesium bromide (1M in THF; 170 ml, 170 mmol) added to the amber reaction mixture in a slow stream via cannula. The reaction was again allowed to room temperature whereupon it was stirred like this for 30 minutes. A reflux condenser was attached to the reaction vessel before oxygen was bubbled through the solution for 40 minutes. The mixture was then stirred for a further 1 hour before carefully pouring onto crushed ice and acidifying to pH 3 with concentrated HCl. The mixture was then extracted using ethyl acetate (3×80 ml). The organic extracts were then treated with 3M sodium hydroxide solution until pH 10 was attained. The basic, aqueous layer was separated, acidified to pH 3 with 2M HCl which caused an oily solid to precipitate. This was dissolved in diethylether (150 ml), dried using MgSO4, filtered and concentrated in vacuo and then recrystallised from ethanol:water (1:1) (250 ml) to give a buff coloured solid that corresponded to the title compound (21.6 g, 96%) and required no further purification. m/z (LC-MS, ESP), RT=3.64 min, (M+H)=201.1

1. temperatureto warm to room temperature
2. stirringstirred like this for 16 hours
3. temperatureThe mixture was then cooled to 0° C.
4. customwas again allowed to room temperature whereupon it
5. stirringwas stirred like this for 30 minutes
6. customwas bubbled through the solution for 40 minutes
7. stirringThe mixture was then stirred for a further 1 hour
8. additionbefore carefully pouring
9. customonto crushed ice and acidifying to pH 3 with concentrated HCl
10. extractionThe mixture was then extracted
11. additionThe organic extracts were then treated with 3M sodium hydroxide solution until pH 10
12. customThe basic, aqueous layer was separated
13. customto precipitate
14. dissolutionThis was dissolved in diethylether (150 ml)
15. customdried
16. filtrationfiltered
17. concentrationconcentrated in vacuo
18. customrecrystallised from ethanol:water (1:1) (250 ml)
19. customto give a buff

ORD record

ord-33f19fa137be4af5abf47f0b8cd81b05

Source dataset

uspto-grants-2010_06

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07732483B2