反应详情

25.5 g (0.17 moles) of compound 12, 3.2 g (0.017 moles) of p-toluenesulfonic acid and 500 ml of hexane were placed in a round-bottomed flask fitted with a Dean-Stark apparatus. This suspension was refluxed for 3 h. After cooling, the hexane fraction was decanted from the insoluble products and the solvent was removed under vacuum to leave an oil, which was then distilled in a short distillation column at 45° C. and 0.03 mbar to give 15 g (yield: 68%) of compound 13. 1H NMR (400 MHz, CDCl3): δ=7.33 (d, J=7.6 Hz. 1H); 7.21 (m, 2H); 7.06 pseudo dt, J=7.2, 1.4 Hz, 1H); 6.45 (bs, 1H); 3.25 (s, 2H); 2.12 (s, 3H).

1. customfitted with a Dean-Stark apparatus
2. temperatureThis suspension was refluxed for 3 h
3. temperatureAfter cooling
4. customthe hexane fraction was decanted from the insoluble products
5. customthe solvent was removed under vacuum
6. customto leave an oil, which
7. distillationwas then distilled in a short distillation column at 45° C.