Vergleich der Produkte aus der Reaktion von Phenylguanidin-Derivaten mit β-Ketoestern bzw. Propiolsäureestern (Synthese von Pyrimidonen)

Comparison of reaction products afforded by phenylguanidine derivatives with β-ketoesters or propiolic esters, respectively (synthesis of pyrimidones). 2-Anilino-imidazolines, when treated with either β-ketoesters or propiolic esters, yield two isomeric groups of pyrimidones. The isomerism is based on different positions of the carbonyl group in the pyrimidone ring. The mass spectra permit an unequivocal assignment of constitution I to the product formed with β-ketoesters and of constitution V to that formed with propiolic esters. Additionally, 2-(2-amino-anilino)-2-imidazoline (XII) when treated with methyl phenylpropiolate yields IX; while treatment with ethyl benzoylacetate yields XIII as an intermediate, which eliminates spontaneously one molecule of water to give the benzimidazole derivative XIV. Phenylguanidines (XV) add propiolic esters in the same way as do imidazoline derivatives. Photochemical cleavage of two carbon atoms with their adherent hydrogen atoms from the imidazole ring of the pyrimidones (V) leads to aminopyrimidine derivatives, e.g. XVI.