Synthesis and Fungicidal Activities of 2-Alkylthio-5-phenylmethylene-4H-imidazol-4-ones

2-Alkylthio-5-phenylmethylidene-4H-imidazol-4-ones 4 were synthesized by S-alkylation of 2-thioxo-3-aryl-4-imidazolidinones 3 , which were obtained via cyclization of isothiocyanate 2 with aromatic primary amines. 3 and 4 exhibited good fungicidal activity against Physalospora piricola .