Synthesis, antifungal activity and SAR of N-substituted and N,N-disubstituted 2,4-dihydroxythiobenzamides

N-Substituted and N,N-disubstituted 2,4-dihydroxythiobenzamides were synthesized and their fungistatic properties were examined. The compounds were prepared by reacting sulfinyl-bis-(2,4-dihydroxythiobenzoyl) with primary or secondary amines. The activities of the derivatives against five phytopathogenic fungi were measured in vitro. The growth-inhibitory activity of these compounds depends mainly on their lipophilicity. Parabolic relationships between growth-inhibitory activity and lipophilicity (calculated n-octanol-water partition coefficient and log k(w) from reversed phase chromatography) were found. The influence of the type of N-substitution on the character of the thioamide bond was analyzed based on H-1 NMR, MS and IR spectra. (c) Pesticide Science Society of Japan.