反应详情

In 50 ml of 48% hydrobromic acid was dissolved 5.0 g (14.5 mmol) of 3-(1-ethoxycarbonyl-4-piperidinyl)-1,2,3,4-tetrahydro-1,6-dimethyl-2,4-dioxoquinazoline (Compound g) obtained in Reference Example 7, and the solution was heated under reflux for 1.5 hours. After evaporation of the solvent, ethanol was added to the residue. The precipitated crystals were collected by filtration to give 5.04 g (yield: 99%) of 1,2,3,4-tetrahydro-1,6-dimethyl-2,4-dioxo-3-(4-piperidinyl)quinazoline hydrobromide as white crystals.

1. customobtained in Reference Example 7
2. temperaturethe solution was heated
3. temperatureunder reflux for 1.5 hours
4. customAfter evaporation of the solvent, ethanol
5. additionwas added to the residue
6. filtrationThe precipitated crystals were collected by filtration