The aza–ene or the Michael addition? Examination of an unusual substituent effect on the reaction of heterocyclic ketene aminals with ethyl propiolate

Synthesis of Functionalized Bicyclic Pyridones Containing the Dithiocarbamate Group Using Thioazlactones, Diamines, and Nitroketene Dithioacetal

An efficient method for the synthesis of highly substituted bicyclic pyridone derivatives containing the dithiocarbamate group is reported via a one-pot three-component reaction of 2-(alkylthio)thio­azlactones, diamines, and nitroketene dithioacetal in EtOH under catalyst-free conditions. The reaction proceeds via a domino amidation–­intramolecular 1,4-addition-type Friedel–Crafts alkylation reaction to afford the corresponding fused bicyclic pyridones with high yields and diastereoselectivity.

Synthesis of bicyclic 2-pyridones by regioselective annulations of heterocyclic ketene aminals with anhydrides

An efficient strategy for the synthesis of substituted bicyclic 2-pyridones is developed. The proposed approach is based on the regioselective N-acylation of heterocyclic ketene aminals (HKAs) with methacrylic anhydride or crotonic anhydride.

Pyrrole- and dihydropyrrole-fused neonicotinoids: design, synthesis, and insecticidal evaluation

Versatile pyrrole- and dihydropyrrole-fused neonicotinoids were obtained from cyclic and non-cyclic nitroeneamines. Anhydrous aluminum chloride (AlCl₃) exhibited high catalytic selectivity for the synthesis of the titled etherified compounds at room temperature and the eliminated products under reflux conditions. The target molecules have been identified on the basis of satisfactory analytical and spectral [¹H and ¹³C nuclear magnetic resonance (NMR), high-resolution mass spectrometry (HRMS), and X-ray] data. All synthesized compounds have been screened for insecticidal activity. The preliminary insecticidal activity results showed that some of the aimed compounds displayed excellent insecticidal activity against cowpea aphids (Aphis craccivora).

Design, synthesis, crystal structure analysis, and insecticidal evaluation of phenylazoneonicotinoids

On the basis of research of the proposed modes of action between neonicotinoids and insect nicotinic acetylcholine receptor (nAChR), a series of phenylazoneonicotinoids were designed and synthesized to further promote the π-π interaction between molecule and amino acid residues. The target compounds have been identified on the basis of satisfactory analytical and spectral ((1)H NMR, (13)C NMR, HRMS, and X-ray) data. The preliminary results revealed that tiny differences in substitutes resulted in different configurations and great bioactivity variations. Some compounds with electron-donating groups on positions 2 and 6 of the phenyl ring presented higher insecticidal activity than imidacloprid against cowpea aphids ( Aphis craccivora ). The impressive crystal structure of the excellent insecticidal activity compound 9q clearly proved that the functional electronegative pharmacophore was approximately vertical to the methyleneimidazolidine plane. The differences in the mode of interaction on nAChR of typical compounds 9h and 9q remain unclear.