Hydrogen Bromide → 1,2,3,4-Tetrahydro-1,6-dimethyl-2,4-dioxo-3-(4-piperidinyl)quinazoline hydrobromide

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Reaction Steps

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.

Provenance & Evidence