反应详情

4-Hydroxybenzofuran (4.9 g. 0.0366 M), ethyl 5-bromopentanoata (7.64 g, 0.0366 M), anhydrous potassium carbonate (5.44 g), sodium iodide (0.2 g) and 95% ethanol (20 ml) were refluxed with stirring for 4.5 hr. The cooled reaction mixture was filtered and the solid washed well with ethanol. The filtrate was evaporated to dryness and the residue partitioned between ether and water. The organic layer was separated and washed with 2N sodium hydroxide solution, water, dried (sodium sulphate) and evaporated to give ethyl 5-(4-benzofuranyloxy)pentanoata as an oil. To this oil was added 95% ethanol (130 ml) and 0.5N sodium hydroxide solution (130 ml) and the mixture stirred at room temperature (3 hr). The solution was evaporated to half-volume, diluted with water and extracted with ether. The aqueous phase was treated with charcoal, filtered and acidified with concentrated hydrochloric acid. The precipitated solid was filtered off, washed wall with water and recrystallised from ethanol-water to give 5-(4-benzofuranyloxy)pentanoic acid, m.p. 107.5° -108.5° C. (Found: C. 66.51; H, 5.90. C13H14O4 requires C, 66.65; H, 6.02%).

1. customThe cooled reaction mixture
2. filtrationwas filtered
3. washthe solid washed well with ethanol
4. customThe filtrate was evaporated to dryness
5. customthe residue partitioned between ether and water
6. customThe organic layer was separated
7. washwashed with 2N sodium hydroxide solution, water
8. dry with materialdried (sodium sulphate)
9. customevaporated
10. customto give ethyl 5-(4-benzofuranyloxy)pentanoata as an oil
11. stirringthe mixture stirred at room temperature (3 hr)
12. customThe solution was evaporated to half-volume
13. additiondiluted with water
14. extractionextracted with ether
15. additionThe aqueous phase was treated with charcoal
16. filtrationfiltered
17. filtrationThe precipitated solid was filtered off
18. washwashed wall with water
19. customrecrystallised from ethanol-water