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

Temperature

5 °C

Kojic acid, 30 g, as added to 150 ml of water and dissolved at 70° C. To the solution was added 30 g of zinc powders and, 90 ml of conc. hydrochloric acid (12 N) was dropwise added to the mixture over 2 hours. The mixture was stirred at the same temperature for 30 minutes. Insoluble matters (zinc powders) were removed and the reaction liquid was cooled to 5° C. After adjusting its pH to 2 with 50% aqueous sodium hydroxide solution, the mixture was concentrated under reduced pressure and the residue was dissolved in 100 ml of dichloromethane. The solution was washed with water (100 ml, 3 times). After drying over anhydrous magnesium sulfate, the system was separated and purified by flash column chromatography (eluting solution; chloroform: methanol=20:1) using Wako Gel C-300 (200 g) to give 2.4 g of the title compound as crystals. Physical data of this compound were identical with those of the compound obtained in Reference Example 11.

1. dissolutiondissolved at 70° C
2. additionwas dropwise added to the mixture over 2 hours
3. customwere removed
4. customthe reaction liquid
5. concentrationthe mixture was concentrated under reduced pressure
6. dissolutionthe residue was dissolved in 100 ml of dichloromethane
7. washThe solution was washed with water (100 ml, 3 times)
8. dry with materialAfter drying over anhydrous magnesium sulfate
9. customthe system was separated
10. custompurified by flash column chromatography (eluting solution; chloroform: methanol=20:1)

ORD record

ord-b5b71cd2c2064c72b52339a06e0f5876

Source dataset

uspto-grants-1991_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05075299