Ring Transformations in Reactions of Heterocyclic Compounds with Nucleophiles. Conversion of 5-Nitropyrimidine into 2-Substituted 5-Nitropyrimidine and 2-Amino-5-nitropyridines by Amidines

Article abstract of DOI:10.1021/jo00345a036

The reaction of 5-nitropyrimidine (1) with benzamidine, pivalamidine, acetamidine, propionamidine, α-phenylacetamidine, O-methylisourea hydrochlorides, and cyanamide in ethanolic solution in the presence of triethylamine has been investigated.It was found that reaction of 1 with alkyl(aryl) amidines, having no active methylene groups attached to the amidine moiety (pivalamidine, benzamidine), exclusively formed the corresponding 2-substituted 5-nitropyrimidines in good yields.With acetamidine and propionamidine, in addition to the formation of the 2-substituted 5-nitropyrimidines, the formation of 2-amino-5-nitropyridines also was observed; with α-phenylacetamidine a 2-amino-5-nitropyridine derivative exclusively was obtained.The reaction of 1 with both O-methylisourea and cyanamide leads to 2-amino-5-nitropyrimidine.These reactions provide new examples of degenerate ring transformations of the pyrimidine ring system and of the ring transformation of pyrimidines into pyridines.