Synthesis and fungicidal activity of 3,4-dichloroisothiazole based strobilurins as potent fungicide candidates

Abstract

A series of 3,4-dichloroisothiazole based novel strobilurin analogs were designed and synthesized, and their structures were elucidated by NMR and HRMS, and the typical crystal structure was determined by X-ray diffraction for validation. Results from different biological assays suggested that most target compounds displayed very good fungicidal activity against one or multiple plant pathogens in vitro and in vivo. Among them, compounds 6d, 6g and 8d showed a broad spectrum of fungicidal activity. Further field experiments indicated that compound 8d displayed better efficacy against Sphaerotheca fuliginea than commercial standards azoxystrobin and trifloxystrobin, and better efficacy against Pseudoperonospora cubensis than trifloxystrobin. Overall, a new fungicidal candidate for plant disease management was discovered in this study.