Synthesis and fungitoxicity of some pyrimidine derivatives.

A series of 12 pyrimidine derivatives were prepared and tested in vitro against growth, sporulation and nucleic acid content of Fusarium oxysporum f. sp. lycopersici and Helminthosporium oryzae. Introduction of a thiazole ring together with two aryl groups into 2-aminopyrimidine brought about drastic toxicity for both fungi. Pyrimidine derivatives with aryl groups alone were less toxic. Nitro groups were found to enhance the toxicity of the pyrimidine derivatives especially when substituted in the ortho-position of the aryl groups. Inhibition of nucleic acid synthesis of both fungi was attributed mainly to the presence of the thiazole ring.