| 摘要 |
<p>Process for the preparation of a 4-chloro-5-alkoxycarbonyl-2-methoxy-pyrimidine of the formula: in which R1 is a lower alkyl radical with 1 to 4 carbon atoms, which comprises the following stages: A) condensation of a salt of O-methylisourea and an inorganic or organic acid, with an alkyl alkoxymethylenemalonate in an aqueous medium and in the presence of an excess of an alkali metal hydroxide. to form the corresponding salt. of the 5-alkoxycarbonyl-4-hydroxy-2-methoxy-pyrimidine, and neutralisation of the said salt by the addition of an inorganic or organic acid, in order to liberate this 5-alkoxycarbonyl-4-hydroxy-2-methoxy-pyrimidine, and B) bringing the latter compound, suspended in dimethylformamide, into contact with thionyl chloride, at room temperature, in order to form the corresponding 4-chloro-5-alkoxycarbonyl-2-methoxy-pyrimidine: Application to the preparation of 6-ethoxycarbonyl-8-ethyl-2-methoxy-5-oxo-5,8-dihydro-pyrido¢2,3-d!pyrimidine.</p> |
