Synthesis and biological activity of new aminosulfenyl derivatives of the methylcarbamate insecticide, carbofuran

A number of new aminosulfenyl derivatives of Carbofuran, linking different N-substituted amino acid esters and its analogs to the carbamyl nitrogen atom of Carbofuran (2, 3-dihydro-2, 2-dimethyl-7-benzofuranyl N-methylcarbamate) through a sulfur bridge, were synthesized, and their insecticidal activity and toxicity to mice were examined. Derivatization generally resulted in substantial improvement in mouse toxicity. All of the derivatized carbamates, with few exceptions, showed good insecticidal activity against houseflies, green rice leafhoppers and aphids in laboratory tests, though they were inferior to the parent methylcarbamate, carbofuran, on a weight basis. However, some derivatives were equally or more effective against these pests on a molar basis. Pot tests in greenhouse or field trials demonstrated that some of the derivatives were as effective as carbofuran even on a weight basis. Virtually all the derivatives tested were less effective inhibitors of acetylcholinesterase than carbofuran.