反应详情

A mixture of 5 g of 4-carbamoyl-4-piperidino-piperidine, 0.5 g of 5% palladium-on-charcoal catalyst and 50 ml of water is boiled under reflux for 50 hours. The reaction mixture is then cooled, and the catalyst is removed by filtration. The filtrate is concentrated and allowed to stand. The precipitated crystals are collected by filtration, dried and recrystallized from chloroform to give 1,2,3,5,6,7,8,8a-octahydro-2-oxo-imidazo[1,2-a]pyridine-3-spiro-4'-piperidine as colorless crystals, m.p. 193° C. 2,3,5,6,7,8-Hexahydro-2-oxo-imidazo[1,2-a]pyridine-3-spiro-4'-piperidine is obtained from the mother liquor. Overall yield is 65%.

1. temperatureunder reflux for 50 hours
2. temperatureThe reaction mixture is then cooled
3. customthe catalyst is removed by filtration
4. concentrationThe filtrate is concentrated
5. filtrationThe precipitated crystals are collected by filtration
6. customdried
7. customrecrystallized from chloroform