A theoretical investigation of the model diazotization/dediazotization of N-aminopiperidine and N-aminomorpholine at the DFT (B3LYP/6-31+G(d)) level indicated that the corresponding cycloimines can be generated transiently, which can be trapped with dimethyl acetylenedicarboxylate (DMAD) to form a 1,4-dipole followed by cycloaddition of the latter with a second molecule of DMAD to give the corresponding pyrido-annelated products. All steps have low activation free energy barriers and are thermodynamically favoured. Based on the theoretical results, we carried out successfully diazotization of N-amino cyclic amines, namely N-aminopiperidine, 4-aminomorpholine and 1-amino-4-methylpiperazine with tert. -butyl nitrite followed by dediazotization to generate transiently the corresponding cycloimines, which could be trapped with dimethyl acetylenedicarboxylate. to afford new annelated pyridine derivatives, namely tetramethyl 9H -5,6,7,8-tetrahydroquinolizine-1,2,3,4-tetracarboxylate, tetramethyl 5,6,8,9-tetrahydropyrido[2,1-c][1,4]oxazine-1,2,3,4-tetracarboxylate and tetramethyl 9H -5,6,7,8-tetrahydro-7-methylpyrido[1,2-a]pyrazine-1,2,3,4-tetracarboxylate which were duly characterized.

中文翻译：

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通过 N-氨基环胺的重氮化/去重氮化生成和捕获非芳香族环亚胺：理论和实验结果

在 DFT (B3LYP/6-31+G(d)) 水平对 N-氨基哌啶和 N-氨基吗啉的模型重氮化/去重氮化的理论研究表明，相应的环亚胺可以瞬时生成，可以用乙炔二甲酸二甲酯捕获（DMAD），以形成1,4-偶极接着后者的环加成与DMAD的第二分子，得到相应的吡啶并 - 稠合的产品。所有步骤都具有低活化自由能垒，并且在热力学上是有利的。基于理论结果，我们成功地进行了N-氨基环胺的重氮化，即N-氨基哌啶、4-氨基吗啉和1-氨基-4-甲基哌嗪与叔。-亚硝酸丁酯，然后去重氮化以瞬时生成相应的环亚胺，它可以被乙炔二羧酸二甲酯捕获。提供新的退火吡啶衍生物，即四甲基 9H -5,6,7,8-四氢喹啉-1,2,3,4-四羧酸酯，四甲基 5,6,8,9-四氢吡啶并[2,1-c][1 ,4]恶嗪-1,2,3,4-四羧酸酯和四甲基 9H -5,6,7,8-四氢-7-甲基吡啶并[1,2-a]吡嗪-1,2,3,4-四羧酸酯，其中被适当地表征。