The insecticidal effects of ω‐hexatoxin‐Hv1a, κ‐hexatoxin‐Hv1c and ω/κ‐hexatoxin‐Hv1h are currently attributed to action at calcium and potassium channels. By characterizing the binding of these toxins to neuronal membranes, we show that they have more potent effects as positive allosteric modulators (PAMs) of insect nicotinic acetylcholine receptors (nAChRs), consistent with their neuroexcitatory toxicology. Alanine scanning analysis of ω‐hexatoxin‐Hv1a reveals a structure–activity relationship for binding that mirrors that for insecticidal activity. Spinosyn A does not compete with ω‐hexatoxin‐Hv‐1a for binding, and we show that these two PAMs have distinct pharmacology of binding indicating that they act at different receptor populations. These toxins represent valuable tools for the characterization of insect nAChRs and for the development of more selective agrochemicals.

The design of a new potent nonsteroidal ecdysone agonist led to the discovery of a diethylaminosulfur trifluoride (DAST)-mediated cyclization of α,α-disubstituted-α-acylaminoketones. The resulting fluorooxazolines can be ring-opened or selectively substituted by a range of nucleophiles to provide in high yields a diverse array of unprecedented heterocyclic frameworks.

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DAST-Mediated Cyclization of α,α-Disubstituted-α-acylaminoketones: Efficient and Divergent Synthesis of Unprecedented Heterocycles. -The title reaction affords a broad spectrum of fluorooxazoline products. As is shown for derivative (IVa), they can be used for further transformation to different types of heterocyclic frameworks. -(BIGOT, A.; BLYTHE, J.; PANDYA, C.; WAGNER, T.; LOISELEUR*, O.; Org. Lett. 13 (2011) 2, 192-195, http://dx.doi.org/10.1021/ol102454e ; Res. Chem., Syngenta Crop Prot. Muenchwilen AG, CH-4332 Stein, Switz.; Eng.) -R. Simon 16-122

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