Pyridine Derivatives as Insecticides─Part 4: Synthesis, Crystal Structure, and Insecticidal Activity of Some New Thienylpyridines, Thienylthieno[2,3-]pyridines, and Related Heterocyclic Derivatives.

The reaction of ethyl 5-cyano-2-methyl-4-(thiophen-2-yl)-6-thioxo-1,6-dihydropyridine-3-carboxylate () with 2-chloroacetamide or its -aryl derivatives gave ethyl 6-((2-amino-2-oxoethyl)thio)-5-cyano-2-methyl-4-(thiophen-2-yl) nicotinate () or its -aryl derivatives -, respectively. Cyclization of - into their isomers - was carried out by heating in absolute ethanol in the presence of a catalytic amount of sodium ethoxide. The -aminoamide was reacted with some aryl aldehydes in refluxing ethanol containing a few drops of conc. HCl to afford the corresponding tetrahydropyrimidinones -. The cyclocondensation reaction of with some cycloalkanones such as cyclopentanone and cyclohexanone gave the corresponding spiro compounds The crystal structures of compounds and were determined by single-crystal X-ray diffraction techniques. All new compounds were evaluated for their insecticidal activity toward nymphs and adults of .