Oxygen → 4-Hydroxydibenzothiophene

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

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

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