反应详情

A solution of methyl N-(p-methoxybenzyl)nipecotate hydrochloride (30.7 g) and 8.4 g of sodium hydroxide in 900 ml of methanol and 45 ml of water is stirred at room temperature for 17 hours. The solution is evaporated to dryness in vacuo, the residue diluted with toluene, and this again evaporated to dryness in vacuo. To the residue is added 1 liter of acetic anhydride and 140 ml of triethylamine, and the resulting mixture is heated under reflux for 4 hours. The reaction mixture is evaporated to dryness in vacuo, the residue taken up in chloroform, washed with water, dried, and concentrated in vacuo. The residual oil is chromatographed on silica gel using 1:1 hexane-ethyl acetate as the eluant, and yields 16.9 g of 1-(p-methoxybenzyl)-3-methylene-2-piperidone as a chromatographically pure yellow oil. Alternatively, the oil can be distilled to give analytically pure 1-(p-methoxybenzyl)-3-methylene-2-piperidone, b.p. 145°-155°/0.05 mm.

1. customThe solution is evaporated to dryness in vacuo
2. additionthe residue diluted with toluene
3. customthis again evaporated to dryness in vacuo
4. additionTo the residue is added 1 liter of acetic anhydride and 140 ml of triethylamine
5. temperaturethe resulting mixture is heated
6. temperatureunder reflux for 4 hours
7. customThe reaction mixture is evaporated to dryness in vacuo
8. washwashed with water
9. customdried
10. concentrationconcentrated in vacuo
11. customThe residual oil is chromatographed on silica gel using 1:1 hexane-ethyl acetate as the eluant