反応 #48904

反応方程式

Hydrochloric acid

1-[3-(Cyclopentyloxy)-2-hydroxy-4-methoxyphenyl]ethanone

sodium hydride

diethyl carbonate

potassium t-butoxide

Potassium t-butoxide

→

8-(cyclopentyloxy)-4-hydroxy-7-methoxy-2H-chromen-2-one

溶媒

water

反応条件

後処理

1. 1
   温度The reaction was refluxed for 1 h
2. 2
   抽出extracted with ethyl acetate (200 mL×2)
3. 3
   その他The combined extracts were dried
4. 4
   ろ過filtered
5. 5
   濃縮concentrated
6. 6
   workup.DISSOLUTIONredissolved in t-butanol (50 mL)
7. 7
   温度the reaction was refluxed
8. 8
   workup.WAITAfter 42 h
9. 9
   workup.WAITAfter an additional 2 d
10. 10
    温度to cool to rt
11. 11
    濃縮concentrated
12. 12
    workup.ADDITIONdiluted with 1N HCl (100 mL)
13. 13
    抽出extracted with ethyl acetate (200 mL×2)
14. 14
    その他The combined extracts were dried
15. 15
    ろ過filtered
16. 16
    濃縮concentrated
17. 17
    その他purified by silica gel chromatography (3:2→0:1; hexanes:ethyl acetate)

実験手順

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.

出典