反应详情

5-Cholesten-3β-ol-thionobenzoate (100 mg, 0.198 mmol), symdibromo-tetrachloroethane (323 mg, 0.991 mmol), and 4-methoxy-4'-dimethylaminodiphenyltellurium dichloride (8.4 mg, 0.0198 mmole) were stirred in a two phase system of chloroform (2 ml) and aqueous potassium carbonate (2.5 ml, 20%) at room temperature for 4 h. T.l.c. (petroleum ether followed by petroleum ether-ethyl acetate 20:1) showed complete reaction. The two phases were separated, the aqueous phase extracted with chloroform (2×5 ml) and the combined chloroform extracts dried over magnesium sulphate. Filtration, evaporation of the solvent and column chromatography (petroleum ether followed by petroleum ether-ethyl acetate 20:1) of the residue afforded 5-cholesten-3β-ol-benzoate (85 mg, 88%) m.p. 143°-145° (lit; 150°-151°). The i.r. spectrum was identical to that of an authentic sample.

1. customreaction
2. customThe two phases were separated
3. extractionthe aqueous phase extracted with chloroform (2×5 ml)
4. dry with materialthe combined chloroform extracts dried over magnesium sulphate
5. filtrationFiltration, evaporation of the solvent and column chromatography (petroleum ether followed by petroleum ether-ethyl acetate 20:1) of the residue