CHEMISTRY OF SYNTHETIC PYRETHROID INSECTICIDES - SOME RECENT ADVANCES

Developments in the chemistry of synthetic pyrethroids made a signific ant impact in the fields of crop protection and disease vector control . A brief survey of the structural modifications in pyrethroid insecti cides originating from natural pyrethrin is presented. The classificat ion of the synthetic pyrethroids into cyclopropane and non-cyclopropan e pyrethroid esters and non-ester pyrethroids is described. Substituti ons in the acid as well as the alcohol moieties resulting into the est ers with either enhanced, reduced or retained insecticidal activity co mpared to the parent compound, are discussed. Studies on the modificat ions of the alcohol moiety resulting into a variety of compounds are d escribed in details. It is pointed out that the modifications in the c entral ester linkage with ether and oxime ether linkages are promising with reduced fish toxicity. Stereochemical requirement for biological activity, synthetic routes for some of the acid and alcohol moieties and role of pyrethroids in insect control are also dealt with. It is c oncluded that pyrethroid insecticides can serve the agricultural as we ll as the public health sectors if used with proper planning.