Abstract Starting from the ethyl 1-aminothieno(furo)[2,3-b]pyridine-2-carboxylates 1 by alkaline hydrolysis the corresponding potassium salts of thieno(furo)[2,3-b]pyridines 2 were obtained. Ongoing to the relevant acids (by treatment with hydrochloric acid), we have observed that while thieno[2,3-b]pyridines were converted into the 1-aminothieno[2,3-b]pyridine-2-carboxylic acids 3a–h in good yields (71−80%), in contrast, the derivatives of furo[2,3-b]pyridines gave the furo[2,3-b]pyridine-1-ones 5 (70−75%). Further, starting from the potassium salts or from amino acids of thieno(furo)[2,3-b]pyridines derivatives by refluxing in acetic anhydride a new heterocyclic system were obtained: 9(10)-methylpyrido[3',2':4,5]thieno(furo)[3,2-d][1,3]oxazin-7(8)-ones (65−89%). Finally the reaction of these latter compounds with benzyl amine or with hydrazine hydrate led to the formation of pyrimidine derivatives: 8(9)-benzyl-9(10)-methylpyrido[3',2':4,5]thieno(furo)[3,2-d]pyrimidin-7(8)-ones 7 (70−81%) and 8(9)-amino-9(10)-methylpyrido[3',2':4,5]thieno(furo)[3,2-d]pyrimidin-7(8)-ones 8 ones (72−81%). The structures of all synthesized compounds were confirmed by NMR, infrared, mass spectrometry data, and by elemental analysis. GRAPHICAL ABSTRACT The reactivity of some ethyl 1-aminothieno(furo)[2,3-b]pyridine-2-carboxylates 1 has been deeply investigated. By treatment with potassium hydroxide and then with hydrochloric acid they can give the relevant acids 3 or the 7,8-dihydro-2H-cyclopenta[d]furo(thieno)[2,3-b]pyridin-1(6H)-ones 5 (by decarboxylation and deamination). The acids 3 or their potassium salts react with acetic anhydride giving a new class of compounds (9(10)-methylpyrido[3',2':4,5]thieno(furo)[3,2-d][1,3]oxazin-7(8)-ones 6, which by reaction with benzylamine or hydrazine hydrate gave the new polyheterocyclic compounds: 8(9)-benzyl-9(10)-methylpyrido[3',2':4,5]thieno(furo)[3,2-d]pyrimidin-7(8)-ones 7 and 8(9)-amino-9(10)-methylpyrido[3',2':4,5]thieno[3,2-d]pyrimidin-7(8)-ones 8.

中文翻译：

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新的杂环系统：吡啶并[2',3':5,4]噻吩并(呋喃)[3,2-d]恶嗪作为合成取代吡啶并[3',2':4,5]噻吩(呋喃)[3,2-d]嘧啶

摘要 以1-氨基噻吩并(呋喃)[2,3-b]吡啶-2-羧酸乙酯1为原料，通过碱水解得到相应的噻吩并(呋喃)[2,3-b]吡啶钾盐2。继续研究相关酸（通过用盐酸处理），我们观察到虽然噻吩并 [2,3-b] 吡啶转化为 1-氨基噻吩并 [2,3-b] 吡啶-2-羧酸 3a-h相比之下，呋喃[2,3-b]吡啶的衍生物以良好的产率（71-80%）得到呋喃[2,3-b]吡啶-1-酮5（70-75%）。此外，从噻吩并（呋喃）[2,3-b]吡啶衍生物的钾盐或氨基酸开始，通过在乙酸酐中回流，获得了新的杂环系统：9（10）-甲基吡啶并[3',2'： 4,5]噻吩（呋喃）[3,2-d][1,3]oxazin-7(8)-ones (65-89%)。最后这些化合物与苄胺或水合肼的反应导致嘧啶衍生物的形成：8(9)-苄基-9(10)-甲基吡啶并[3',2':4,5]噻吩并(呋喃) [3,2-d]pyrimidin-7(8)-ones 7 (70−81%) 和 8(9)-amino-9(10)-methylpyrido[3',2':4,5]thieno(furo) )[3,2-d]pyrimidin-7(8)-ones 8 个 (72−81%)。所有合成化合物的结构均通过核磁共振、红外、质谱数据和元素分析确认。图形摘要已深入研究了一些 1-氨基噻吩并（呋喃）[2,3-b] 吡啶-2-羧酸乙酯 1 的反应性。通过用氢氧化钾和盐酸处理，他们可以得到相关的酸 3 或 7,8-二氢-2H-环戊二烯[d]呋喃（噻吩并）[2,3-b]吡啶-1（6H）-酮5（通过脱羧和脱氨基）。