The selective condensation of a-dicarbonyl comlane-2-carboxaldehyde 0-(methylcarbamoy1)oxime pounds with one equivalent of a dithiol followed by has exhibited especially outstanding greenhouse and oxime formation and subsequent carbamoylation field control of nematodes with no phytotoxicity. has afforded a series of novel a-mercaptol 0-Structure us. activity relationships appear to be (carbamoyl)oximes, some of which possess good consistent with previously studied cholinesteraseto excellent insecticidal, acaricidal, and nematicidal inhibiting carbamates. Toxicological aspects are activity. The compound 2,4-dimethyl-1,3-dithiodiscussed.he continuing search for improved carbamate insecticides has led, in the last decade, to a class of potent T acetylcholinesterase inhibitors derived from a variety of oxime precursors. For example, significant pesticidal activity has been reported for 0-(carbamoy1)oximes of cycloaliphatic and bicyclic ketones (Kilsheimer and Manning, 1963;Weiden, 1968), 2-keto-1,3-dithiolanes (Addor, 1965), 5-keto-l,3-dithianes (Addor, 1968), alkoxy and alkylthio esters (Felton, 1968), and trisubstituted acetaldehydes (Payne et al., 1966;Weiden, 1968). Detailed structure ES. activity studies of the latter class of compounds, exemplified by 2-methyl-2-(methylthio)propionaldehyde 0-(methylcarbamoy1)-oxime (aldicarb, Temik, UC 21149), have defined certain important criteria for high or optimum acetylcholinesterase inhibition. These include a conformational similarity to acetylcholine, the presence of an a-alkylthio (or electronegative) substituent, and monomethylation of the carbamate nitrogen. The special role of sulfide sulfur is also apparent in other 0-(methylcarbamoy1)oximes ; for example, Smethyl N-[(methylcarbamoyl)oxy]thioacetimidate (methomyl, Lannate, DuPont 1179), in substituted thiophenyl carbamates (Mahfouz ef a/., 1969), and in the case of certain (methylcarbamoy1oxy)benzaldehyde mercaptals (Durden and Weiden, 1969;Nikles, 1969). The present work describes a new series of insecticidalnematicidal a-mercaptol 0-(carbamoy1)oximes of general structure I. The compound 2,4-dimethyl-1,3-dithiolane-2-carboxaldehyde 0-(methylcarbamoy1)oxime (MBR 6168, Tirpate) has demonstrated especially outstanding greenhouse and field nematode control with no phytotoxicity, and is currently under development by 3M Company. 0 0 II RIS -C I -CR3 II R,S NOCNReRs ii CH 3 < ? \OCNHCH3
