Synthesis And Fungicidal Activities Of 2-Substituted Imidazolones

Imidazolones have been found to show fungicidal, herbicidal, pestcidal and medicinal activities, and have the applied foreground extensively. In this paper, we studied the synthesis of novel imidazolones by utilizing aza-Wittig reaction that has the advantage of easily accessible starting material, mild condition and good yields. The spectral properties, biological activities and the condition for cyclization of imidazolones were also researched and some of them were found to show good fungicidal activities. One hundred and ten unreported imidazolones in four series were synthesized. It may be summarized as follows:1. The cyclization of carbodiimide 2 with 4-methylthiophenol in presence of solid potassium carbonate was studied further. The results show that it is a good method for preparing of 2-(4-methylthiophenyloxy)-5-arylmethylidene-4H-imidazolin-4-ones 4 at room temperature.2. 2-Thio-3-alkyl(aryl)-4-imidazolidinones 10 were firstly synthesized from aza-Wittig reaction in a very mild condition by two methods. Method B is better than method A because it uses easily accessible carbon disulfide and alkyl(aryl) amines instead of high priced and poisonous isocyanates. By using these new methods, we can introduce various alkyl(aryl) to the position 2 of 2-thio-4-imidazolidinones, which is very useful intermediates for preparing various 2-alkylthio-3-alkyl(aryl)-5-arylmethylidene-4H-imidazolin-4-ones 11 and condensed heteroaromatic imidazolones.3. The S-alkylate of 2-thio-3-alkyl(aryl)-4-imidazolidinones 10 withalkylhalides in presence of solid potassium carbonate was studied. The results show that it is a good method for preparing of 2-alkylthio-3-alkyl(aryl)-5-phenylmethylidene-4H-imidazolin-4-ones 11 at 20-60.4. The cyclization of carbodiimide 2 with alcohols in presence of sodium alkoxide was studied firstly. The results show that it is a good method for preparing of 2-alkyloxy-5-arylmethylidene-4H-imidazolin-4-ones 15 at 20-70.5. The biological activities of partial imidazolones were studied. The results showed that they exhibited fungicidal activities. Especially, 2-(4-me-thylthiophenyloxy)-5-arylmethylidene-4H-imidazolin-4-ones 4 and 2-alkylthio-5-phenylmethylidene-4H-imidazolin-4-ones 11 containing alkylthio substituent exhibited good fungicidal activities. Most of them exhibited more than 80%(grade B) inhibition of partial fungi in 50mg/L. The best two were compounds 4r and 4s which exhibited 100% inhibition of Pyricularia oryzae, Pellicularia sasakii, Cercospora asparagagas and Physalospora piricola in 50mg/L.