[CH3:1][O:2][C:3]1[N:8]=[C:7]([O:9][CH3:10])[C:6]([C:11]([OH:13])=[O:12])=[CH:5][N:4]=1.[CH2:14](N(CC)CC)C>CN(C)C=O>[CH3:1][O:2][C:3]1[N:8]=[C:7]([O:9][CH3:10])[C:6]([C:11]([O:13][CH3:14])=[O:12])=[CH:5][N:4]=1To a suspension of 2,4-Bis(methyloxy)-5-pyrimidinecarboxylic acid (Prep31, 1.000 g, 5.43 mmol) in N,N-Dimethylformamide (DMF) (35 mL) at 0° C. N,N′-Carbonyldiimidazole (1.321 g, 8.15 mmol) was added and the mixture was stirred for 1 hour at 0° C., then left stirring at rt. After 4 h Triethylamine (2.271 mL, 16.29 mmol) and N,N′-Carbonyldiimidazole (1.321 g, 8.15 mmol), were added to the white suspension. After other 4 h, N,N′-Carbonyldiimidazole (1.321 g, 8.15 mmol) of another batch was added to the suspension. The reaction was left overnight at rt. The solution was then concentrated in vacuo and methanol was added. The solution was stirred at reflux for 2 h. Then the mixture was evaporated in vacuo, the residue was dissolved in DCM and washed with NaHCO3 sat. sol. and then with H2O. Organic phase was dried with Na2SO4 anhydrous, filtered and evaporated in vacuo to obtain 550 mg of the title compound, which was used in the following step without further purification.
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