Synthesis and fungicidal activity of 2-pyridinecarboxamide cyclohexylsulfonamides

In order to explore the fungicidal activity and structure-activity relationship of cycloalkylsulfonamides, 15 2-pyridinecarboxamide cyclohexylsulfonamides were synthesized and their activities against Botrytis cinerea were tested by in vitro mycelial growth rate method and in vivo leaf method. The title compounds were designed and synthesized by the reaction between pyridine formyl chloride and 2-amino cyclohexylsulfonamides, which was obtained from the reduction amination reaction using 2-oxocyclohexenylsulfonamides as the starting materials. The bioassay exhibited that all the compounds possessed fungicidal activities against B. cinerea and other five phytopathogenic fungi. Notably, compound V-8 showed good activity with the EC50 value of 1.41 mg/L in vitro and the control efficiency of 79.17% in vivo against B. cinerea. Moreover, some of these compounds exhibited the inhibition rate of more than 60% against Rhizoctonia solani Kühn, Pyricularia grisea, Pythium aphanidermatum, Fusarium oxysporium and Phytophthora capsici. Compound V-7, with the EC50 value of 2.7 mg/L, showed better activity than carbendazim (with the EC50 value of 4.4 mg/L) against Pythium aphanidermatum. These promising compounds had great potentials for further research.