5-benzoyl-1,3-dimethyl-1,3-diazinane-2,4,6-trione

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A mixture of 1,3-dimethylbarbituric acid (5 g, 32.02 mmol), 4-dimethylaminopyridine (4.74 g, 38.79 mmol) in dry CH2Cl2 (75 ml) was cooled to 0° C. and benzoyl chloride (4.95 g, 35.22 mmol) added dropwise in 15 min. The reaction mixture was stirred for 3 h at room temperature, diluted with CH2Cl2 (150 ml) and washed with 2 N HCl solution (40 ml). The organic phase was dried over MgSO4 and evaporated. The residue was crystallised from diisopropylether then recrystallised from MeOH, giving 5-benzoyl-1,3-dimethyl-2,4,6(1H,3H,5H)-pyrimidinetrione 3 (5.32 g, 64%). washed with 2 N HCl solution (40 ml) The organic phase was dried over MgSO4 evaporated The residue was crystallised from diisopropylether then recrystallised from MeOH