Specific Features of Tosylation of 2-Substituted Pyrimidin-4(3H)-ones Containing a Double Bond in the α-Position of the Side Chain

The reaction of 2-(1-hydroxyimino-2-oxo-2-phenylethyl)-6-R-pyrimidin-4(3 H )-ones with an excess of p -toluenesulfochloride proceeds in two stages involving consecutive oxidation of the oxygen atom of the hydroxyimino group and the oxygen atom of the amide fragment of the pyrimidine ring. The reaction of the resulting ditosylates with ethylenediamine proceeds via replacement of the sulfonyl group in the 2-position of the pyrimidine ring. The examples of 2-[1-benzoyl-2-(2-furyl)vinyl]-6-methylpyrimidin-4(3 H )-one, 2-[2-(4-nitrophenyl)vinyl]-6-methylpyrimidine-4(3 H )-one, and 6-methyl-2-(2-oxo-2-phenylethylthio)pyrimidin-4(3 H )-one were used to consider the relationship between the structure of the substrate and the direction of the tosylation reaction.