Studies On Synthesis And Biological Activities Of Benzothiadiazoles Induced-Resistance Compounds

This paper summarys plant inducer's mechanism and application on plant disease protection. S-methyl benzo[d][l,2,3]thiadiazole-7-carbothioate ( BTH ) as one of a new plant inducer has been widely studied rencently, and has been already used as pesticide in agriculture.In this study, new benzo[d][l,2,3]thiadiazole derivatives were designed according to relationship of structure and efficacy. The 9 novel compounds were synsthesized with following reactions.The chlorine atom in 2-chloro-3,5-dinitro-benzoic acid as beginning raw material was substituted by 2-methylpropane-2-thiol, esterified then with bromoethane, reduced by iron powder and cyclized to obtain ethyl benzo[d][l,2,3]thiadiazole-7 (intermediate I) after diazonation reation. Intermediate I was reduced at -78℃ by DIBAL-H to obtain benzo[d][l,2,3]thiadiazole-7-carbaldehyde, and benzo[d][l,2,3]thiadiazole-7-carbaldehyde treated via Wittig-Horner reaction to (E)-3-(benzo[d][l,2,3]thiadiazol-7-yl)acrylic acid esters as target compounds. All compounds were confirmed by 'HNMR, IR and elemental analysis.(E)-methyl 3-(benzo[d][l,2,3]thiadiazol-7-yl)acrylate estersBioassy results showed all novel compounds exhibit certain fungicidal activity in vitro, but no fungicidal activity in vivo.