Synthesis of Stereoisomers of Ipconazole and Their Fungicidal and Plant Growth Inhibitory Activities

Abstract

Two racemic diastereomers 5a and 5b, both of which are active ingredient of a seed treatment fungicide on rice, ipconazole, (1RS, 2SR, 5RS; 1RS, 2SR, 5SR)-2-(4-chlorobenzyl)-5-isopropyl-1-(1H-1, 2, 4-triazol-1-ylmethyl)cyclopentanol, and two other racemic diastereomers (1RS, 2RS, 5RS)-5c and (1RS, 2RS, 5SR)-5d were synthesized, and fungicidal activity and plant growth inhibitory activity were examined. Enantiomers of 5a and 5b were prepared, and their fungicidal activities were also examined. Racemic diastereomers 5a, 5b and 5d were more active than 5c in fungicidal activity (EC₅₀ value) in vitro on Gibberella fujikuroi, Cochliobolus miyabeanus and Pyricularia oryzae. In plant growth inhibitory activity test for seed treatment on rice, only 5d was slightly active in the first sheath growth inhibition. The comparative test of enantiomers in vitro revealed that the fungicidal activities of (-)-5a and (-)-5b were higher than those of corresponding (+)-5a and (+)-5b, respectively.