Tandem one-pot five-component reaction involving saccharin, propargyl bromide, aldehyde, hydroxylamine hydrochloride, and non-conjugated primary amine has been explored for a rapid and an efficient synthesis of isoxazole-secondary sulfonamides. This novel multicomponent reaction involves one pot Npropargylation of saccharin, oximation, and 1,3-dipolar cycloaddition, followed by an intermolecular ring-opening reaction by N-nucleophilic amine. This transformation is catalyzed by CaCl 2 /K 2 CO 3 and activated under ultrasonic cavitation. The CaCl 2 salt is reported for the first time as a new precatalyst and a chlorine source. We showed that ultrasound, using sonotrode, significantly improved the reaction compared to ultrasonic bath and magnetic stirring. The isoxazole-secondary sulfonamides 6 a-r were obtained in good to excellent yields (75-96 %) and withing shorter reaction times (13-17 min). All the synthesized compounds were fully characterized by IR, MS-ESI, 1 H NMR, 13 C NMR spectroscopy, X-ray crystallography and HPLC analysis.

In this work, a novel compound N-(3-(4-methoxyphenyl)isoxazolin-5-yl)methylsaccharin has been synthesized. The molecular structure of the compound was determined using various spectroscopic techniques and confirmed by a single-crystal X-ray diffraction analysis. In the single crystal, C–H…O hydrogen bonds between neighboring molecules form chains along the a-axis direction. Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H…H (35.7%), H…O/O…H (33.7%), and H…C/C…H (13%) interactions. The optimized structure calculated using density functional theory at the B3LYP/6–311 G(d,p) level is compared with the experimentally determined structure in the solid state. The calculated highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy gap is 4.9266 eV.

BACKGROUNDSphodroxia maroccana Ley is a pest of cork oak crops that damages the roots of seedlings and can severely impair cork oak regeneration. Since the banning of carbosulfan and chlorpyriphos, which were widely used against the larvae of Sphodroxia maroccana because of their harmful impact on the environment, until now there has been no pesticide against these pests. Therefore, it is particularly urgent to develop highly effective insecticidal molecules with novel scaffolds. Isoxazolines are a class of insecticides that act on γ‐aminobutyric acid (GABA)‐gated chloride channel allosteric modulators. In this work, a green synthesis of novel 3,5‐disubstituted isoxazoline‐sulfonamide derivatives was achieved in water via ultrasound‐assisted four‐component reactions, and their insecticidal activities against fourth‐instar larvae of S. maroccana were evaluated.RESULTSMost of the tested compounds showed insecticidal activity compared to fluralaner as positive control and commercially available insecticide. Especially, the isoxazoline‐secondary sulfonamides containing halogens (Br and Cl) on the phenyl group attached to the isoxazoline, 6g (LC50 = 0.31 mg/mL), 6j (LC50 = 0.38 mg/mL), 6k (LC50 = 0.18 mg/mL), 6L (LC50 = 0.49 mg/mL), 6m (LC50 = 0.24 mg/mL), 6q (LC50 = 0.46 mg/mL), exhibited much higher larvicidal activity than fluralaner (LC50 = 0.99 mg/mL).CONCLUSIONNovel isoxazolines containing sulfonamide moieties were designed, synthesized and confirmed by two single‐crystal structures of 4e and 6q. Their bioassay results showed significant larvicidal activity with significant morphological changes in vivo. These results will lay the foundation for the further discovery and development of isoxazoline‐sulfonamide derivatives as novel crop protection larvicides of cork oak. © 2023 Society of Chemical Industry.

In this work, we present an efficient one-pot method for the synthesis of three new azo-isoxazoline derivatives (4a–c) from aromatic aldehydes, hydroxylamine hydrochloride and 4-(allyloxy)azobenzene. Thus, the azo-isoxazoline derivatives (4a–c) were synthesized via 1,3-dipolar cycloaddition using sodium dichloroisocyanurate (SDIC) as an eco-friendly and inexpensive oxidizing agent under ultrasound cavitation in water as a green solvent. The desired compounds 4a–c were obtained in high to excellent yields of 75–90%.

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