Hydrochloric Acid → Deferiprone

2-methyl-3-(benzyloxy)-4-pyranone (10.4 g) was dissolved in water (80 mL) and ethanol (80 mL). Methylamine hydrochloride (4.9 g) was dissolved in water (50 mL) and sodium hydroxide was added (2.9 g). This solution was added to the solution of 2-methyl-3-(benzyloxy)-4-pyranone, followed by the addition of 2N sodium hydroxide (4.0 mL). This solution was placed under conditions of reflux for 18 hours. After this time, the pH of the solution was set to 1.1 with hydrochloric acid, and the solution was concentrated. Water was added (80 mL), and the sample was washed with diethyl ether. The resulting precipitate was dissolved in ethanol, and the pH was set to 7.8 with 10N sodium hydroxide. The solution was extracted three times with methylene chloride, and these aliquots were combined and dried over sodium sulfate. After decanting, the solvent was removed by rotary evaporation, resulting in an orange oil. This oil was dissolved in ethanol and hydrochloric acid, and the solvent was removed by rotary evaporation, resulting in a yellow solid. This solid was recrystallized from ethanol and diethyl ether resulting in a white powder. This solid was dissolved in ethanol (70 mL) and water (5 mL) and 5% palladium on charcoal catalyst (0.26 g) was added. The resulting mixture was placed under 1 atm. of hydrogen for 12 hours. Following filtration, the solvent was removed by rotary evaporation resulting in a white solid. This was recrystallized from ethanol and diethyl ether, resulting in a white powder (2.1 g). Proton NMR (D20): 7.79 (d, 1H), 6.89 (d, 1H), 3.79 (s, 3H). 2.38 (s, 3H).

1. temperatureof reflux for 18 hours
2. concentrationthe solution was concentrated
3. additionWater was added (80 mL)
4. washthe sample was washed with diethyl ether
5. dissolutionThe resulting precipitate was dissolved in ethanol
6. extractionThe solution was extracted three times with methylene chloride
7. dry with materialdried over sodium sulfate
8. customAfter decanting
9. customthe solvent was removed by rotary evaporation
10. customresulting in an orange oil
11. customhydrochloric acid, and the solvent was removed by rotary evaporation
12. customresulting in a yellow solid
13. customThis solid was recrystallized from ethanol and diethyl ether resulting in a white powder
14. dissolutionThis solid was dissolved in ethanol (70 mL)
15. additionwater (5 mL) and 5% palladium on charcoal catalyst (0.26 g) was added
16. filtrationfiltration
17. customthe solvent was removed by rotary evaporation
18. customresulting in a white solid
19. customThis was recrystallized from ethanol and diethyl ether

ORD record

ord-40e1410ad2e94c0fb6add2a9cec9e4ab

Source dataset

uspto-grants-2001_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06294152B1