[Na].Cl.[NH2:3][C:4]([NH2:6])=[NH:5].[CH3:7][O:8][C:9](=[O:21])[N:10]=[CH:11][CH2:12][C:13](OCCOCC)=[O:14]>CO>[NH2:5][C:4]1[NH:6][C:13](=[O:14])[CH:12]=[C:11]([NH:10][C:9]([O:8][CH3:7])=[O:21])[N:3]=110 g of sodium are dissolved in 200 ml of absolute methanol, whereupon the solution is treated with 30 g of guanidine hydrochloride. While stirring there is added thereto a solution of 50 g of methyl[(1-ethoxy-2-ethoxycarbonyl)ethylidene]carbamate in 150 ml of absolute methanol. The resulting suspension is stirred overnight and thereafter concentrated at 40° in a water-jet vacuum. 600 ml of water are added to the residue and the resulting suspension is adjusted to pH 5 with glacial acetic acid while stirring. The resulting precipitate is filtered off under suction, washed with 250 ml of water and dried at 50° in vacuo. There is obtained methyl 2-amino-1,6-dihydro-6-oxo-4-pyrimidinecarbamate which is uniform according to thin-layer chromatography.
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