反应详情

To a solution of 24a (0.26 g, 1.0 mmol) in anhydrous ethyl ether (4 ml) was added dropwise a solution of PBr3 (0.13 g, 0.5 mmol) in anhydrous ethyl ether (1 ml) and the reaction mixture was kept at reflux temperature for 2 hours under nitrogen. Anhydrous ethanol was added (0.2 ml) and the resulting solution was heated to reflux temperature for another hour. Five ml of an aqueous solution of 5% Na2CO3 were then added, the organic phase was separated, anhydrified and evaporated. The crude product was chromatographed (hexane and chloroform 1:1) to give 25a (0.2 g, 64% yield) as colourless prisms: melting point 115-116° C. (cyclohexane); 1H NMR (CDCl3) δ7.46-7.09 (m, 4H); 6.93 (m, 1H), 6.39 (m, 1H), 6.12 (m, 1H), 5.75 (dd, 1H, J=6.9, 2.6 Hz), 5.07 (dd, 1H, J=14.7, 2.6 Hz), 4.61 (dd, 1H, J=14.7, 6.9 Hz). Anal. (C12H10BrNOS): C, H, N.

1. temperatureat reflux temperature for 2 hours under nitrogen
2. temperaturethe resulting solution was heated
3. temperatureto reflux temperature for another hour
4. customthe organic phase was separated
5. customevaporated
6. customThe crude product was chromatographed (hexane and chloroform 1:1)