Antifungal and Plant Growth Inhibitory Activities of Stereo and Optical Isomers of 2-Triazolylcycloalkanol Derivatives

Abstract

The cis- and trans-isomers of l-(4-chlorophenyl)-2-(lH-l,2,4-triazol-l-yl)cycloheptanol (1. 2) were compared in antifungal and plant growth-inhibitory activities. The ci5-isomer of triazolylcycloheptanol had stronger antifungal activity against most fungi than the trans-isomer in vitro. Against Rosellinia nacatrix, however, the trans-isomer showed much stronger antifungal activity than the cis-isomer. In preventive activity against cucumber gray mold, powdery mildew, sclerotinia rot and rice blast, the cis-isomer was much stronger than the trans-isomer. In disease-controlling activity against wheat powdery mildew and oat crown rust, the cis-isomer was slightly stronger than the trans-isomer, whereas against rice sheath blight both isomers were similarly active. On the other hand, the trans-isomer had much stronger inhibitory activity than the cis-isomer on the growth of rice seedlings. Diastereomers of l-substituted-2-(lH-l,2,4-triazol-l-yl)cyclohexanols (3–8) were also compared in biological activity. In disease-controlling activity the cis-isomers were more effective than the corresponding trans-isomers against cucumber gray mold and powdery mildew. In plant growth inhibitory activity the trans-isomers were more effective than the as-isomers on rice seedlings. Between the two enantiomers of cfs-l-(4-chlorophenyl)-2-(lH-l,2,4-triazol-l-yl)cycloheptanol (1), the preventive activity of the (/)-enantiomer was about two times stronger than that of the (d)-enantiomer against cucumber gray mold and powdery mildew. The (/)-enantiomer also had stronger growth inhibitory activity on rice seedlings than the (d)-enantiomer. © 1991, Pesticide Science Society of Japan. All rights reserved.