Successive Protonation of an N‐Heterocyclic Imine Derived Carbonyl: Superelectrophilic Dication Versus Masked Acylium Ion,Angewandte Chemie International Edition

当前位置： X-MOL 学术 › Angew. Chem. Int. Ed. › 论文详情

Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)

Successive Protonation of an N‐Heterocyclic Imine Derived Carbonyl: Superelectrophilic Dication Versus Masked Acylium Ion
Angewandte Chemie International Edition ( IF 16.1 ) Pub Date : 2018-11-15 , DOI: 10.1002/anie.201810709
Ying Kai Loh ₁ , M. Ángeles Fuentes ₁ , Petra Vasko ₁ , Simon Aldridge ₁

Affiliation

Carbonyl cations are among the most commonly invoked reactive intermediates in organic synthesis. While Olah pioneered superacids to provide a “stable ion” environment for their study in situ, isolated examples are rare. Here, we disclose successive protonation of an N‐heterocyclic imine (NHI) derived carbonyl compound (IDippN)₂CO, 2, to the monocation [(IDippN)(IDippNH) CO]⁺, [3]⁺, and the doubly protonated dication [(IDippNH)₂CO]²⁺, [4]²⁺. [3]⁺ represents a rare example of an N‐protonated carbonyl cation and [4]²⁺ the first example of a superelectrophilic carbonyl dication. All three compounds have been characterized by X‐ray crystallography and IR spectroscopy, revealing stepwise strengthening of the C=O bond on protonation. The unique stability of these systems is attributed to the enhanced basicity and steric profile provided by the NHI substituents. In addition, we report the related singly NHI‐stabilized cation [IDippNCO]⁺, [5]⁺. Crystallographic and DFT analyses provide insight into the interaction between the carbonyl fragment and the NHI, which reveals that the [CNCO]⁺ unit (isoelectronic to CCCO) can be described as an acylium cation “masked” as a cumulene.

中文翻译：

N杂环亚胺衍生的羰基的连续质子化：超亲电子阳离子与掩盖A离子

羰基阳离子是有机合成中最常用的反应性中间体。尽管Olah率先提出了超强酸，可为他们的原位研究提供“稳定的离子”环境，但很少有孤立的例子。在这里，我们公开了N-杂环亚胺（NHI）衍生的羰基化合物（IDippN）₂ CO，2连续质子化为单阳离子[（IDippN）（IDippNH）CO] ⁺，[ 3 ] ⁺以及双质子化指示[（IDippNH）₂ CO] ₂⁺，[ 4 ] ²⁺。[ 3 ] ⁺代表N-质子化的羰基阳离子和[ 4 ] ²⁺的罕见例子超亲电羰基阳离子的第一个例子。这三种化合物均已通过X射线晶体学和红外光谱进行了表征，揭示了质子化过程中C = O键的逐步增强。这些系统的独特稳定性归因于NHI取代基提供的增强的碱性和空间分布。此外，我们报告了单独的NHI稳定阳离子[IDippNCO] ⁺，[ 5 ] ⁺。晶体学和DFT分析提供了对羰基片段与NHI之间相互作用的深入了解，这揭示了[CNCO] ⁺单元（与CCCO等电子化）可被描述为被掩盖为异丙苯的”鎓阳离子。

更新日期：2018-11-15

点击分享查看原文

点击收藏

阅读更多本刊新发论文本刊介绍/投稿指南