Synthesis and antifungal activity of novel piperidinyl thiazole derivatives

As an investigative program around the development of novel oomycetes fungicides, a systematic exploration of piperidinyl thiazole fungicides employing a bioisosteric replacement strategy was planned.

A series of novel piperidinyl thiazole analogues were designed, synthesised, and evaluated as fungicides in vitro and in vivo against three oomycete fungal pathogens: Phytophthora infestans (P. infestans), Plasmopara viticola (P. viticola), and Pseudoperonospora cubensis (P. cubensis). Variation at four different regions of piperidinyl thiazole fungicides like Oxathiapiprolin and Fluoxapiprolin was considered. All variations delivered excellent in vitro and in vivo activity against P. infestans at extremely low concentrations. O-linked heterocyles, bicyclic piperidines, and sulfoximine-substituted aryls demonstrated the most robust transfer of in vitro activity into the greenhouse, while pyridones, acylated sulfoximines, and sultams showed less consistent results concerning the transfer. Specific compounds were selected for deeper evaluation of oomycetes activity. Several of them with representatives of all the series showed an excellent in vivo activity against P. viticola and P. cubensis. Among the most active compounds, P14 and P25 were further profiled in advanced studies and were found to have a robust curative potential. P14, P15, and P25 provided excellent control of P. infestans (in potato), P. viticola (in grapes), and P. cubensis (in cucumber) in field trials at dose rates of 20 and 30 g per hectare.

A bioisosteric replacement strategy was successfully employed to identify novel piperidine thiazole derivatives with robust and commercially interesting control of oomycetes diseases in the greenhouse and under field conditions. A systematic exploration of various modifications of the piperidine thiazole class and their structure activity relationships was described. © 2024 Society of Chemical Industry.