Proinsecticide candidates N-(5-methyl-2-oxo-1,3-dioxol-4-yl)methyl derivatives of imidacloprid and 1-chlorothiazolylmethyl-2-nitroimino-imidazolidine

Prodrugs of imidacloprid and the thiazolylmethyl analog masked with oxodioxolylmethyl group on the N3 site were prepared. The prodrugs decomposed in a buffer solution of pH 8.3 and in a physiological salt solution with half-lives of 10–15 h, releasing the parent insecticides. Being consistent with this, an inward current was evoked in dissociated cockroach neurons treated with the masked compound solutions, which were maintained for 24 h after preparation, as measured using patch–clamp electrophysiology, whereas no response was observed in neurons when the solutions were challenged immediately after preparation. The insecticidal test on the American cockroach showed that the minimum lethal dose for each compound at 24 h after injection was 6.4 × 10−8 mol, which was similar to that for imidacloprid and the thiazolyl derivative. This result strongly suggested a regeneration of the active ingredients in vivo.