activity against the insect species D. melanogaster, Plutella xylostella and Heliothis virescens at 1000 mg.ml21. Intrigued by a possible extension of the privileged nature of this structural scaffold to crop protection research, we embarked on an optimization program around this initial lead which resulted in the identification of highly potent and selective insecticides such as SYN351 and SYN876. The Fischer-Indole reaction was found to be a reliable route for the synthesis of spiro compounds as previously described, and this methodology was improved and applied to the convergent functionalization of the indoline or the piperidine nitrogen. We also devised a novel route based on an intramolecular Heck reaction for the synthesis of spiroindolines with electron-poor aromatic rings as well as the further functionalization of the piperidine ring . The latter route was used for the synthesis of the radioligand SYN876 after tritiation of the piperidine double bond. The biological activity of a selected set of compounds against Spodoptera littoralis, H. virescens and P. xylostella is shown in 3 Spiroindoline Insecticides Act by Inhibiting VAChT these two compounds were selected for further biological evaluation and mode of action studies. As a representative member of the family, the lead Spiroindoline SYN876 is slightly basic, displays high lipophilicity, low water solubility, ” and exhibits moderate photostability. Its efficacy in the field against representative lepidopteran pests is shown in 4 Spiroindoline Insecticides Act by Inhibiting VAChT 5 Spiroindoline Insecticides Act by Inhibiting VAChT of insecticidal activity, SYN876 presents a favourable acute oral toxicity in rats. The Effects of Insecticidal Spiroindolines on “9580632
“1235481-90-9 web Caenorhabditis Elegans and Characterization of Resistant Mutants Spiroindolines are toxic to C. elegans, in which they induce an uncoordinated “loopy”, coiling locomotion and reduced frequency of pharyngeal pumping, symptoms that are similar to the phenotypes of mutants in which neuromuscular cholinergic signalling is reduced. Animals bearing a partial loss of function mutation in choline acetyltransferase, which produce reduced levels of acetylcholine, are hypersensitive to Spiroindolines. One simple explanation for these observations is that the Spiroindolines somehow act to reduce the availability of acetylcholine at the synapse. To test this hypothesis more directly, we examined the interaction of SYN876 with the cholinesterase inhibitor aldicarb. Exposure to aldicarb leads to muscle hypercontraction and eventual ” nematode death, and mutants such as cha-1 that produce reduced levels of acetylcholine are resistant to aldicarb since they are more able to tolerate some increase in synaptic acetylcholine levels than wild-type nematodes. Furthermore, low levels of aldicarb suppress the movement and growth defects of these mutants. We therefore reasoned that if the Spiroindolines act to reduce synaptic acetylcholine levels, they would be able to suppress the effects of aldicarb. Consistent with this hypothesis, sub-lethal doses of SYN876 ameliorated the 
effects of aldicarb exposure. Chemical mutagenesis generated C. elegans mutants resistant to Spiroindolines. The low frequency of recovery and genetic dominance of the mutations indicated that resistance was due to gain of function. Mutations conferring resistance mapped to a 5 map unit interval on Chromosome IV that contains the genes for VAChT and ChAT . The apparent req
