Synthesis of Alkylene-Tethered Bis-Imidacloprid Derivatives as Highly Insecticidal and Nerve-Exciting Agents with Potent Affinity to [3H] Imidacloprid-Binding Sites on Nicotinic Acetylcholine Receptor

Bivalent molecules of bis-imidacloprid with 2-10 alkylene tethers as well as tethers containing an ethenylene, ethynylene, phenylene and oxide joint were prepared. These dimeric chloronicotinyl molecules were highly insecticidal against American cockroaches on injection at 2-30 nanomolar doses. The minimum lethal dose of the most potent hexamethylene derivative was close to that of imidacloprid, and the potency was augmented up to about thirty-five-fold following pretreatment with metabolic inhibitors, while the binding affinity to [ 3 H]imidacloprid-binding sites on the nicotinic acetylcholine receptor was weaker than that of imidacloprid by a factor of 160. The hexamethylene derivative elicited impulses in cockroach central nerves with an initial excitation and subsequent block at a potency comparable to imidacloprid.