Abstract

Efficient gram-scale, one-pot approaches to azidocyanobutyrates and their amidated or decarboxylated derivatives have been developed, starting from commercially available aldehydes and cyanoacetates. These techniques combine (1) Knoevenagel condensation, (2) Corey–Chaykovsky cyclopropanation and (3) nucleophilic ring opening of donor-acceptor cyclopropanes with the azide ion, as well as (4) Krapcho decarboxylation or (4′) amidation. The synthetic utility of the resulting γ-azidonitriles was demonstrated by their transformation into tetrazoles via intramolecular (3+2)-cycloaddition. A condition-dependent activation effect of the α-substituent was revealed in that case. Thermally activated azide–nitrile interaction did not differentiate the presence of an α-electron-withdrawing substituent in γ-azidonitriles, whereas the Lewis acid mediated (SnCl₄ or TiCl₄) reaction proceeded much easier for azidocyanobutyrates. This allowed us to develop an efficient procedure for converting azidocyanobutyrates into the corresponding tetrazoles.

中文翻译：

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γ-叠氮基丁腈的一锅合成及其分子内环加成

摘要

从市场上可买到的醛和氰基乙酸酯开始，已经开发了有效的克级一锅法制备叠氮基氰基丁酸酯及其酰胺化或脱羧衍生物。这些技术将（1）Knoevenagel缩合，（2）Corey-Chaykovsky环丙烷化和（3）供体-受体环丙烷与叠氮化物离子的亲核开环，以及（4）Krapcho脱羧或（4'）酰胺化。通过分子内（3 + 2）-环加成将它们转化为四唑，证明了所得γ-叠氮腈的合成效用。在这种情况下，揭示了α-取代基的条件依赖性激活作用。热活化的叠氮化物-腈相互作用无法区分γ-叠氮腈中存在α电子吸电子取代基，而路易斯酸介导的（SnCl对于叠氮基氰基丁酸酯，₄或TiCl ₄）反应更容易进行。这使我们能够开发一种将叠氮基氰基丁酸酯转化为相应的四唑的有效方法。