反应详情

1-[3-(Cyclopentyloxy)-2-hydroxy-4-methoxyphenyl]ethanone (4.25 g, 17 mmol) was added portionwise to a mixture of sodium hydride (1.4 g, 60%, 35 mmol) and diethyl carbonate (30 mL) at rt under N2. The reaction was refluxed for 1 h and then cooled to rt. 10% Hydrochloric acid (30 mL) was added, and the mixture was stirred for 1 h. The reaction was diluted with water (100 mL) and extracted with ethyl acetate (200 mL×2). The combined extracts were dried, filtered, concentrated, and redissolved in t-butanol (50 mL). Potassium t-butoxide (4.0 g, 36 mmol) was added, and the reaction was refluxed. After 42 h, additional potassium t-butoxide (2.0 g, 18 mmol) was added. After an additional 2 d, the reaction was allowed to cool to rt, concentrated, diluted with 1N HCl (100 mL), and extracted with ethyl acetate (200 mL×2). The combined extracts were dried, filtered, concentrated, and purified by silica gel chromatography (3:2→0:1; hexanes:ethyl acetate) to give 8-(cyclopentyloxy)-4-hydroxy-7-methoxy-2H-chromen-2-one: MS (ESI): 277.1.

1. temperatureThe reaction was refluxed for 1 h
2. extractionextracted with ethyl acetate (200 mL×2)
3. customThe combined extracts were dried
4. filtrationfiltered
5. concentrationconcentrated
6. dissolutionredissolved in t-butanol (50 mL)
7. temperaturethe reaction was refluxed
8. waitAfter 42 h
9. waitAfter an additional 2 d
10. temperatureto cool to rt
11. concentrationconcentrated
12. additiondiluted with 1N HCl (100 mL)
13. extractionextracted with ethyl acetate (200 mL×2)
14. customThe combined extracts were dried
15. filtrationfiltered
16. concentrationconcentrated
17. custompurified by silica gel chromatography (3:2→0:1; hexanes:ethyl acetate)