Abstract
Derivatives of (RS)-2-[(2-furylmethyl) (imidazol-1-ylcarbonyl) amino] alkanoate were synthesized in large numbers and their fungitoxic activity against Gibberella fujikuroi, Cochliobolus miyabeanus and Pyricularia oryzae was measured in in vitro and in vivo tests. Most of the compounds exhibited strong activity against G. fujikuroi; besides, some of them were also highly fungitoxic against C. miyabeanus and P. oryzae. Their activity varied according to the carbon chain length of substituents R1 at α-position of the alkanoates and R2 at the ester moiety. The result of in vitro evaluation showed that compounds having ethyl or n-propyl groups at R1 and alkyl or alkenyl groups with four to seven carbon numbers, cycloalkylalkyl or aralkyl groups at R2, had good activity. It also suggested that the distance between the furan ring and the nitrogen atom at α-position of alkanoates played a role in determining antifungal activity. In addition, replacement of the furan ring with tetrahydrofuran, or imidazole ring with triazole decreased the activity. Among the compounds tested in the in vitro and in vivo tests, 4-pentenyl (RS)-2-[(2-furylmethyl) (imidazol-1-ylcarbonyl)-amino] butanoate was most promising in activity against the three species of fungi causing no phytotoxicity and was chosen for further evaluation to be put into practical use.
