反应详情

The above ketal was hydrogenated over a rhodium-on-alumina catalyst as follows: After dissolving 16 g of ethyl 2-(2-cyanoethyl)acetoacetate ethyleneketal in 90 ml of 10% ethanolic ammonia, 2 g of 5% rhodium-on-alumina were added, and the mixture hydrogenated at low pressure. The catalyst was separated by filtration, and the solvent removed from the filtrate to yield, as a residue, ethyl 2-(3-aminopropyl)acetoacetate ethyleneketal formed in the above hydrogenation. NMR indicated a mixture of the expected ketal plus some cyclized product produced by the next reaction step. The crude product from the above reaction was therefore heated in toluene solution for about 2 hours to convert the amino derivative to 3-acetyl-2-piperidone ethyleneketal. NMR showed the reaction being incomplete at this point; heating in toluene was therefore continued for 7 more hours. NMR again showed incomplete reaction; so heating was continued overnight. After a total of 24 hours of heating under reflux, the reaction mixture was cooled, and the solvent was removed in vacuo.

1. additionwere added
2. customThe catalyst was separated by filtration
3. customthe solvent removed from the filtrate
4. customto yield, as a residue