反应详情

温度

141 °C

101.9 g (0.649 mol) of the mixture of 2,3-diacetoxy-4-methyl-piperidine-1-carboxylic acid methyl ester and 3-acetoxy-2-hydroxy-4-methyl-piperidine-1-carboxylic acid, was concentrated under reduced pressure until a solid formed. The solid was then added to a 2 L round bottom flask equipped with a nitrogen outlet, condenser and thermocouple. To this mixture was added acetic anhydride (430 ml) and then refluxed at 141° C. for two hours. The solution was stirred overnight at room temperature. Most of the acetic anhydride was removed under reduced pressure and the remaining amount was removed by adding H2O (400 ml) and a 5% solution of NaHCO3 until the pH>7. The aqueous mixture was extracted with ethyl acetate (3×250 ml), the organic layers were combined and the ethyl acetate was removed under reduced pressure. Approximately 119.0 g of a thick brown oil material 5-acetoxy-4-methyl-3,4-dihydro-2H-pyridine-1-carboxylic acid methyl ester was recovered. The TLC indicates conversion to product 5-acetoxy-4-methyl-3,4-dihydro-2H-pyridine-1-carboxylic acid methyl ester as the major component. The material was split evenly into two portions for separate hydrolysis reactions.

1. customformed
2. additionThe solid was then added to a 2 L round bottom flask
3. customequipped with a nitrogen outlet, condenser
4. customMost of the acetic anhydride was removed under reduced pressure
5. customthe remaining amount was removed
6. additionby adding H2O (400 ml)
7. extractionThe aqueous mixture was extracted with ethyl acetate (3×250 ml)
8. customthe ethyl acetate was removed under reduced pressure
9. customApproximately 119.0 g of a thick brown oil material 5-acetoxy-4-methyl-3,4-dihydro-2H-pyridine-1-carboxylic acid methyl ester was recovered
10. customThe material was split evenly into two portions
11. customfor separate
12. customhydrolysis reactions