反应详情

p-Toluenesulfonic acid monohydrate (1.5 g) was added to a solution (600 ml) of ethyl 1-benzyl-4-oxo-3-piperidinecarboxylate (CAS Registry No. 1454-53-1, 44.7 g) and ethylene glycol (100 ml) in toluene and the resultant mixture was heated under reflux overnight. After cooling the mixture to room temperature, ice water (500 ml) and a saturated aqueous solution (300 ml) of sodium bicarbonate were added thereto followed by extraction with ethyl acetate (400 ml) for three times. The organic phase was washed successively with water (200 ml) twice and brine (300 ml) and dried over anhydrous magnesium sulfate. The residue was purified by silica gel column chromatography (hexane/ethyl acetate system) to give the title compound (30.4 g) as a yellow oil (yield: 66%).

1. temperatureunder reflux overnight
2. extractionthereto followed by extraction with ethyl acetate (400 ml) for three times
3. washThe organic phase was washed successively with water (200 ml) twice
4. dry with materialbrine (300 ml) and dried over anhydrous magnesium sulfate
5. customThe residue was purified by silica gel column chromatography (hexane/ethyl acetate system)