Breaking C–C (sp3–sp3) σ bonds in 1,4-diazabicyclo[2.2.2]octane (DABCO) by oxidation with antimony pentachloride

Organic chemistry frontiers : an international journal of organic chemistry Pub Date : 2026-07-01 Epub Date: 2026-04-13 DOI:10.1039/d5qo01513h

Lilia M. Baldauf, David G. Villarreal, Guodong Rao, Nathan Yoshino, Heejune Park, James C. Fettinger, Lee-Ping Wang, R. David Britt, Alan L. Balch

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Abstract

Evidence for the oxidative cleavage of the C–C (sp³–sp³) σ bond of DABCO (1,4-diazabicyclo[2.2.2]octane) is reported. Two crystalline salts have been characterized by XRD analysis, which provides insight into the possible mechanism of bond scission that occurred. EPR and ENDOR spectra of the reaction solutions show the existence of two radical species: the delocalized DABCO˙⁺ cation, where the electron is delocalized between the two nitrogen nuclei, and a localized DABCO˙⁺ radical cation with two different hyperfine couplings to the two nitrogen atoms. Computations suggest that the latter radical is DABCO˙⁺ complexed with SbCl₅. DFT and mechanistic analysis provides possible mechanisms for the C–C bond scission, including a newly proposed intermediate: the methylenevinylpiperazine (MVP) radical cation.

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五氯化锑氧化破坏1,4-重氮杂环[2.2.2]辛烷（DABCO）中C-C (sp 3 -sp 3) σ键

报道了DABCO（1,4-重氮双环[2.2.2]辛烷）的C-C (sp 3 -sp 3) σ键氧化断裂的证据。通过x射线衍射分析对两种结晶盐进行了表征，为键断裂发生的可能机制提供了线索。反应溶液的EPR和ENDOR谱显示了两种自由基的存在：电子在两个氮原子之间离域的DABCO•+阳离子和与两个氮原子具有不同超细耦合的局部DABCO•+阳离子自由基。计算表明后一种自由基为DABCO•+与SbCl5络合。DFT和机理分析提供了C-C键断裂的可能机制，包括一种新的中间体：甲基乙烯基哌嗪（MVP）自由基阳离子。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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Organic chemistry frontiers : an international journal of organic chemistry

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7.80

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0.00%

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