反应详情

In particular, 2-ethyl-3-hydroxy-4-pyrone (24.7 g) in 225 ml of methanol is added to 25 ml of water containing 7.5 g of sodium hydroxide. To this solution is added benzyl chloride (25.5 g) and the mixture is then refluxed for 6 hours. Upon cooling, the solvent is removed under reduced pressure. The residue is treated with 50 ml of water and then extracted three times with 25-ml aliquots of dichloromethane. The combined extracts are washed twice with 5% (w/v) sodium hydroxide, then twice with 25 ml of water and dried over magnesium sulfate. Evaporation of the solvent yields crude 3-benzyloxy-2-ethyl-4-pyrone. This crude pyrone (24.4 g) and 1.56 g of methylamine hydrochloride are then dissolved in 300 ml of aqueous ethanol (100 ml) containing 2 g of sodium hydroxide. The solution is stirred at room temperature for 6 days, acidified to pH 2 with concentrated hydrochloric acid, and then evaporated to dryness. The residue is washed with water and extracted twice into chloroform (50 ml). The combined extracts are dried over anhydrous magnesium sulfate and evaporated to dryness yielding 3-benzyloxy-2-ethyl-1-methylpyrid-4-one. To 2 g of this pyrid-4-one is added concentrated hydrobromic acid (10 ml). The reaction mixture is heated on a steam bath for 30 minutes and the product recrystallized from water to yield 2-ethyl-3-hydroxy-1-methylpyrid-4-one.

1. temperaturethe mixture is then refluxed for 6 hours
2. temperatureUpon cooling
3. customthe solvent is removed under reduced pressure
4. additionThe residue is treated with 50 ml of water
5. extractionextracted three times with 25-ml aliquots of dichloromethane
6. washThe combined extracts are washed twice with 5% (w/v) sodium hydroxide
7. dry with materialtwice with 25 ml of water and dried over magnesium sulfate
8. customEvaporation of the solvent
9. customyields crude 3-benzyloxy-2-ethyl-4-pyrone
10. customevaporated to dryness
11. washThe residue is washed with water
12. extractionextracted twice into chloroform (50 ml)
13. dry with materialThe combined extracts are dried over anhydrous magnesium sulfate
14. customevaporated to dryness