Synthesis and biological activity of 3,4-dichloroisothiazole-5-carboxylic amides

Isothiazole based heterocyclic compounds had various biological activities.In order to enlarge the library of novel elicitor lead with broad spectrum of highly systemic acquired resistance,a series of 3,4-dichloroisothiazole-5-carboxylic amides were synthesized by the reaction of carboxylic acid chlorination and condensation with 3,4-dichloroisothiazole-5-carboxylic acid as starting materials.All the ten novel compounds synthesized were confirmed by 1H NMR,IR and elemental analysis.Biological screening indicated that,compound Ⅲe presented broad-spectrum of fungicidal activity at 50 μg/mL against nine fungi with inhibition above 50%.Most compounds had good anti-tobacco mosaic virus(TMV) activity or systemic acquired resistance for tobacco against TMV at 100 μg/mL,among them,compound Ⅲa and Ⅲi exhibited 41.88% and 42.92% of good systemic acquired resistance for tobacco against TMV respectively.