Hydrochloric Acid → 4H-Pyran-4-one, 2-EtOMe-5-hydroxy-

60 ml of water was put in a 100 ml-Erlenmeyer flask, and 10.07 g (0.24 mol) of lithium hydroxide monohydrate and then 11.37 g (0.08 mol) of kojic acid were added thereto and dissolved with stirring. While the temperature of the resulting solution was kept at 40 to 45° C., 14.80 g (0.096 mol) of diethyl sulfate was dropwise added thereto over a period of 20 minutes. Afterwards, the whole was stirred for a further 30 minutes at the same temperature and then overnight at room temperature. The pH of the reaction mixture was adjusted to 6.0 by 1N hydrochloric acid. Water was removed from the reaction mixture using an evaporator by distillation under reduced pressure, and the remaining reddish brown viscous liquid was extracted three times each with 70 ml of a hot benzene. The resulting extract was dewatered by adding anhydrous magnesium sulfate thereto, and then filtered. Benzene was removed from the resulting filtrate using an evaporator by distillation under reduced pressure. The remaining yellowish brown viscous liquid was cooled to solidify (Crude yield: 3.67 g (27%), m.p. 68 to 70° C.). The yellowish brown solid was recrystallized three times from di-isopropyl ether using active carbons to obtain a pure white crystal of 2-ethoxymethyl-5-hydroxy-γ-pyrone.

1. dissolutiondissolved
2. customwas kept at 40 to 45° C.
3. stirringAfterwards, the whole was stirred for a further 30 minutes at the same temperature
4. customovernight
5. customat room temperature
6. customWater was removed from the reaction mixture
7. customan evaporator
8. distillationby distillation under reduced pressure
9. extractionthe remaining reddish brown viscous liquid was extracted three times each with 70 ml of a hot benzene
10. extractionThe resulting extract
11. additionby adding anhydrous magnesium sulfate
12. filtrationfiltered
13. customBenzene was removed from the resulting filtrate
14. customan evaporator
15. distillationby distillation under reduced pressure
16. temperatureThe remaining yellowish brown viscous liquid was cooled
17. customThe yellowish brown solid was recrystallized three times from di-isopropyl ether using active carbons

ORD record

ord-12e573b626544b3b8609846891f5f6f2

Source dataset

uspto-grants-1992_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05102661