Structure-activity relationships of the azole fungicide metconazole and its related azolylmethylcycloalkanols

Metconazole, (1RS, 5RS; 1RS, 5SR)-5-(4-chlorobenzyl)-2,2-dimethyl-1-(1H-1, 2, 4-triazol-1-ytmethyl)cyclopentanol, is a novel triazole fungicide contai ning a cyclopentane ring. The related compounds, cyclopentanol, cyclohexano l and cycloheptanol derivatives having none or gem-dimethyl groups at the 2 -position on the cycloalkane ring were synthesized, and their fungicidal ac tivities were compared. The gem-dimethyl groups at the 2-position on the cy clohexane and cycloheptane rings were important for fungicidal activity as well as the case of the cyclopentanols. The cis-isomers of the cyclopentano ls and the cycloheptanols showed higher fungicidal activities than the tran s-isomers of them. On the contrary, the trans-isomers of the cyclohexanols were more active than the cis-isomers of them, but less active than the cis -isomers of the cyclopentanols and the cycloheptanols. Among the cis-cycloa lkanols, the cyclopentanols and the cycloheptanols showed higher activities than the cyclohexanols. The conformational analysis of these cycloalkanols indicated that the relative three-dimensional orientation of the two impor tant aromatic rings, triazole and benzene, of the cycloalkanols affected th eir fungicidal activities.