Pyridine Derivatives
as InsecticidesPart 4:
Synthesis, Crystal Structure, and Insecticidal Activity of Some New
Thienylpyridines, Thienylthieno[2,3‑b]pyridines,
and Related Heterocyclic Derivatives
posted on 2023-11-09, 07:07authored byEtify A. Bakhite, Suzan Abuelhassan, Mohamed A. Gad, Abdu E. Abdel-Rahman, Omaima F. Ibrahim, Islam S. Marae, Shaaban K. Mohamed, Joel T. Mague, Ayman Nafady
The reaction of ethyl 5-cyano-2-methyl-4-(thiophen-2-yl)-6-thioxo-1,6-dihydropyridine-3-carboxylate
(1) with 2-chloroacetamide or its N-aryl
derivatives gave ethyl 6-((2-amino-2-oxoethyl)thio)-5-cyano-2-methyl-4-(thiophen-2-yl)
nicotinate (2a) or its N-aryl derivatives 2b–f, respectively. Cyclization of 2a–f into their isomers 3a–f was carried out by heating in absolute ethanol
in the presence of a catalytic amount of sodium ethoxide. The o-aminoamide 3a was reacted with some aryl
aldehydes in refluxing ethanol containing a few drops of conc. HCl
to afford the corresponding tetrahydropyrimidinones 4a–d. The cyclocondensation reaction of 3a with some cycloalkanones such as cyclopentanone and cyclohexanone
gave the corresponding spiro compounds 5a,b. The crystal
structures of compounds 2a and 2d were determined
by single-crystal X–ray diffraction techniques. All new compounds
were evaluated for their insecticidal activity toward nymphs and adults
of Aphis gossypi.