Ethyl Acetate → 2,3-Dihydro-1-benzofuran-6-ol

Temperature

0 °C

6-Hydroxy-2H-benzofuran-3-one (3 g) was suspended in anhydrous tetrahydrofuran under an argon atmosphere and cooled to 0° C. Lithium aluminium hydride (20 ml of a 1M solution in tetrahydrofuran) was added dropwise over 10 min and the reaction allowed to reach room temperature over 2 hours. The reaction was cooled to 0° C. and treated dropwise with saturated ammonium chloride solution. Ethyl acetate (200 ml) was added and the mixture filtered through Celite. The ethyl acetate layer was separated, dried (MgSO4) and evaporated to dryness under reduced pressure. The resulting mixture of 2,3-dihydro-benzofuran-3,6-diol and benzofuran-6-ol (approximately 1:1 by 250 MHz 1H NMR) was dissolved in a mixture of hydrochloric acid (200 ml, 5M aqueous solution) and methanol (300 ml) and palladium hydroxide (0.5 g) added. The mixture was stirred under a hydrogen atmosphere for 3 hours then filtered through Celite. The organics were removed by evaporation under reduced pressure and the resulting solution neutralised with concentrated anmmonia solution. The product was extracted into dichloromethane. The dichloromethane solution was dried (MgSO4) and evaporated to dryness under reduced pressure to yield the title compound (2.5 g, 92%). 1H NMR (250 MHz, CDCl3) δ: 3.11 (2H, t, J=8.4 Hz), 4.57 (2H, t, J=8.4 Hz), 6.27-6.34 (2H, m), 6.92-7.02 (1H, m); m/z (API+): 139.1 (M+3H+).

1. temperatureThe reaction was cooled to 0° C.
2. filtrationthe mixture filtered through Celite
3. customThe ethyl acetate layer was separated
4. dry with materialdried (MgSO4)
5. customevaporated to dryness under reduced pressure
6. additionThe resulting mixture of 2,3-dihydro-benzofuran-3,6-diol and benzofuran-6-ol (approximately 1:1 by 250 MHz 1H NMR)
7. dissolutionwas dissolved in a mixture of hydrochloric acid (200 ml, 5M aqueous solution) and methanol (300 ml) and palladium hydroxide (0.5 g)
8. additionadded
9. filtrationthen filtered through Celite
10. customThe organics were removed by evaporation under reduced pressure
11. concentrationwith concentrated anmmonia solution
12. extractionThe product was extracted into dichloromethane
13. dry with materialThe dichloromethane solution was dried (MgSO4)
14. customevaporated to dryness under reduced pressure

ORD record

ord-78e10d4ff96e4836bd6e7d0a7d12433f

Source dataset

uspto-grants-2002_10

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06465493B1