Verfahren zur Herstellung von 4-Hydroxy-5-halogen-pyrimidinen

摘要

The invention comprises pyrimidines of the general formula wherein R1 and R2, which may be the same or different, represent hydrogen atoms or straight or branched chain alkyl groups containing 1 to 5 carbon atoms, and Hal represents a halogen atom-particularly fluorine, chlorine or iodine; and the preparation thereof by heating compounds of the general formula wherein Hal has the above significance, R2 has the above significance or represents a carbalkoxy group, R3 represents the methyl or ethyl group, and R4 represents hydrogen, an alkali metal or the methyl or ethyl group with compounds of the general formula wherein Y has the same significance as R1 or represents the group R5S in which R5 represents hydrogen or an alkyl group containing 1 to 4 carbon atoms or an aralkyl group and, when R2 represents a carbalkoxy group, hydrolysing and decarboxylating the product and when Y represents the group R5S desulphurizing the product to replace the R5S group by a hydrogen atom, for example by reaction with Raney nickel or an oxidation reagent such as hydrogen peroxide or nitric acid. The reactant of the third formula above may be thiourea in a tautomeric form. Ethyl a - methoxymethylene - a - fluoroacetate is prepared by reacting ethyl fluoroacetate, methyl formate and sodium enolate and then dimethyl sulphate. Sodium enolate of ethyl ethoxyalyfluoroacetate is prepared by reacting ethyl oxalate, ethyl fluoroacetate and sodium ethylate. Ethyl isovaleroylfluoroacetate is prepared by reacting the sodium salt of ethyl fluoroacetate and isovaleroyl chloride. Ethyl n-valeroyl-fluoroacetate is prepared in a similar manner. Sodium enolate of ethyl formylchloroacetate is prepared by reacting sodium ethylate, ethyl formate and ethylchloroacetate.