反应详情

The ethyl ester from (a) (343 mg, 2.04 mmol) was dissolved in ethanol (5 ml). A 5M aqueous solution of sodium hydroxide (0.82 ml, 4.04 mmol) was added. The solution was stirred at reflux for 3h whereupon a precipitate was formed, and all starting material had disappeared as indicated by tlc. After cooling, the ethanol was removed by evaporation and water (10 ml) was added. The basic solution was extracted with dichloromethane (10 ml) which was discarded. The aqueous layer was acidified with 2M hydrochloric acid and then extracted with ethyl acetate (2×10 ml). The organic layer was dried, filtered and evaporated to leave the title compound (b) (206 mg, 72%) as a sweet-smelling white solid, m.p. 84°-5° C. from ethanol and diethylether.

1. customwas formed
2. temperatureAfter cooling
3. customthe ethanol was removed by evaporation and water (10 ml)
4. additionwas added
5. extractionThe basic solution was extracted with dichloromethane (10 ml) which
6. extractionextracted with ethyl acetate (2×10 ml)
7. customThe organic layer was dried
8. filtrationfiltered
9. customevaporated