Ethyl 5-cyano-1,6-dihydro-2-methyl-4-(2′-thienyl)-6-thioxonicotinate (A) 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 (1a) or its isomeric thieno[2,3-b]pyridine 2a. 3-Aminothieno[2,3-b]pyridine-2-carboxamide 2b was also synthesized by the reaction of A with 2-chloroacetamide. The reaction of 1a with hydrazine hydrate in boiling ethanol gave acethydrazide 3. Heating ester 1a with hydrazine hydrate under neat conditions afforded 3-amino-1H-pyrazolo[3,4-b]pyridine 10. Compounds 2b, 3, and 10 were used as precursors for synthesizing other new thieno[2,3-b]pyridines and pyrazolo[3,4-b]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 Aphis gossypii (Glover,1887). Some compounds such as 4, 9b, and 9c showed promising results. The effect of some sublethal concentrations, less than LC₅₀, of compounds 4, 9b, and 9c on the examined Aphis was subjected to a further study. The results demonstrated that exposure of A. gossypii nymphs to sublethal concentrations of compounds 4, 9b, and 9c 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.

中文翻译：

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作为杀虫剂的吡啶衍生物。第五部分. 主要含有烟酸乙酯支架的新型噻吩并[2,3-b]吡啶和吡唑并[3,4-b]吡啶及其对棉蚜的杀虫活性（Glover，1887）


合成5-氰基-1,6-二氢-2-甲基-4-(2'-噻吩基)-6-硫代烟酸乙酯(A)，在乙酸钠或碳酸钠存在下与氯乙酸乙酯反应，得到5-氰基-1,6-二氢-2-甲基-4-(2'-噻吩基)-6-硫代烟酸乙酯(A)。 -氰基-6-((2-乙氧基-2-氧代乙基)硫基)-2-甲基-4-(2'-噻吩基)烟酸酯(1a)或其异构体噻吩并[2,3-b]吡啶2a。 3-氨基噻吩[2,3-b]吡啶-2-甲酰胺2b也通过A与2-氯乙酰胺的反应合成。 1a与水合肼在沸腾的乙醇中反应得到乙酰肼3。在纯净条件下将酯1a与水合肼加热得到3-氨基-1H-吡唑并[3,4-b]吡啶10。使用化合物2b、3和10作为合成其他主要含有烟酸乙酯支架的新噻吩并[2,3-b]吡啶和吡唑并[3,4-b]吡啶的前体。所有新化合物的结构均通过元素和光谱分析得到确认。评估了大多数获得的化合物对棉蚜若虫和成虫的杀虫活性（Glover，1887）。 4、9b 和 9c 等一些化合物显示出有希望的结果。化合物 4、9b 和 9c 的某些亚致死浓度（低于 LC ₅₀ ）对所检测的蚜虫的影响有待进一步研究。结果表明，将棉蝇若虫暴露于亚致死浓度的化合物 4、9b 和 9c 对其生物学参数（即若虫龄期持续时间、世代时间和成虫寿命）有显着影响。所有三种化合物的最高浓度 C1 都会增加若虫的龄期和世代时间，并缩短成虫的寿命，反之亦然。