反应详情

Trifluoroacetic anhydride (28.2 mL, 203 mmol) was added dropwise to an ice cooled solution of the product from preparation 20 (˜135 mmol) in dichloromethane (500 mL), the mixture was allowed to warm to room temperature and stirred overnight. Tic analysis indicated still largely starting material so a further portion of trifluoroacetic anhydride (15 mL, 108 mmol) was added dropwise and the mixture was allowed to stir for a further 27 hours. The reaction was quenched by the cautious addition of methanol (250 mL) and left to stir for 30 minutes before being concentrated in vacuo. 2.5 M sodium hydroxide (100 mL) was then added cautiously and the mixture was extracted with dichloromethane (4×100 mL). The combined organic extracts were dried (MgSO4) and evaporated to give the desired product (12 g, 64%) contaminated with recovered starting material (˜15 mol %). 1H NMR (CDCl3, 400 MHz) δ 3.80 (3H, s), 4.40 (1H, br), 4.66 (2H, s), 7.16 (1H, dd), 7.20 (1H, d), 8.17 (1H, d).

1. additionwas added dropwise
2. stirringto stir for a further 27 hours
3. customThe reaction was quenched by the cautious addition of methanol (250 mL)
4. waitleft
5. stirringto stir for 30 minutes
6. concentrationbefore being concentrated in vacuo
7. addition2.5 M sodium hydroxide (100 mL) was then added cautiously
8. extractionthe mixture was extracted with dichloromethane (4×100 mL)
9. dry with materialThe combined organic extracts were dried (MgSO4)
10. customevaporated