Pyridine Derivatives as Insecticides. Part 5. New Thieno[2,3-]pyridines and Pyrazolo[3,4-]pyridines Containing Mainly Ethyl Nicotinate Scaffold and Their Insecticidal Activity toward (Glover,1887).

Ethyl 5-cyano-1,6-dihydro-2-methyl-4-(2'-thienyl)-6-thioxonicotinate () was synthesized and reacted with ethyl chloroacetate in the presence of sodium acetate or sodium carbonate to give ethyl 5-cyano-6-((2-ethoxy-2-oxoethyl)thio)-2-methyl-4-(2'-thienyl)nicotinate () or its isomeric thieno[2,3-]pyridine . 3-Aminothieno[2,3-]pyridine-2-carboxamide was also synthesized by the reaction of with 2-chloroacetamide. The reaction of with hydrazine hydrate in boiling ethanol gave acethydrazide . Heating ester with hydrazine hydrate under neat conditions afforded 3-amino-1-pyrazolo[3,4-]pyridine . Compounds , and were used as precursors for synthesizing other new thieno[2,3-]pyridines and pyrazolo[3,4-]pyridines containing mainly the ethyl nicotinate scaffold. Structures of all new compounds were confirmed by elemental and spectral analyses. Most of the obtained compounds were evaluated for their insecticidal activity toward the nymphs and adults of (Glover,1887). Some compounds such as , and showed promising results. The effect of some sublethal concentrations, less than LC, of compounds , and on the examined was subjected to a further study. The results demonstrated that exposure of nymphs to sublethal concentrations of compounds , and had noticeable effects on their biological parameters, i.e., nymphal instar duration, generation time, and adult longevity. The highest concentration C1 of all three compounds increased the nymphal instar duration and generation time and decreased adult longevity and vice versa.