Discovery of 5-(5,5-Dimethylbutenolide-3-ethylidene)-2-amino-imidazolinone Derivatives as Fungicidal Agents

The novel fungicidal agents 5-(5,5-dimethylbutenolide-3-ethylidene)-2-amino-imidazolinone derivatives, were designed and synthesized in moderate to excellent yields in four steps by αa-hydroxyketone and diketene as raw materials and characterized by HR-ESI-MS and 1H-NMR. The preliminary bioassay showed that some of these compounds, such as 4a, 4e and 5g exhibit 94.9%, 92.8% and 81.4% inhibition rates against Sclerotinia scleotiorum at the concentration of 50 µg/mL, respectively. The EC50 values of compounds 4e and 4i were 4.14 and 3.27 µM against Alternaria Solani, and 5g had EC50 value of 3.23 µM against S. scleotiorum. Compounds 4d and 4g displayed 98.0% and 97.8% control of spore germination against Botrytis cinerea at the concentration of 100 µg/mL, respectively.