Synthesis and antimicrobial activities of hexaconazole derivatives

In order to improve broad-spectrum characteristics and antimicrobial activities of hexaconazole on wood-rotting fungi and moulds, valeryl chloride and substituted benzene were used as raw materials and eight compounds were synthesized by Friedel-Crafts acylation, Corey-Chaykovsky reaction and 1,2-epoxide opening reaction based on the chemical structure of hexaconazole. These compounds were confirmed by MS and 1H-NMR. Wood-rotting fungi such as white-rot fungi (Coriolus versicolor and Irpex lacteus), brown-rot fungi (Gloeophyllum trabeum and Postia placenta) and mould (Aspergillus niger) were used to test the antimicrobial activities of the compounds by filtering paper method. The results showed that the compounds had obvious antimicrobial activities on the fungi in the concentration range of 0.5%-2.0% except compounds A4 and A5,and the antimicrobial activities increased with the increase of solution concentration. The antimicroial activities of compound C3 were the best and significantly better than those of hexaconazole. The antimicrobial activities of compound C2 on wood-rotting fungi were superior to hexaconazole; however, such effects on mould were worse than those of hexaconazole. The antimicrobial effects of compounds A1, A2, A3 and C1 were not as good as hexaconazole, and compounds A4 and A5 had little inhibitory activities on wood-rotting fungi. The conclusion was that the introduction of isobutyl group in tertiary alcohol carbon,2,4-dichlorophenyl and 2,4-difluorophenyl was conducive to increasing antimicrobial activities of target compounds.