文献类型：期刊文献

英文题名：Concurrent Radical Addition and [3+2] Cycloaddition between Nitrones and Maleimide-Based Acyclic Enediynes

作者：Li, Jing[1];Zhang, Mengsi[1];Huang, Shuai[1];Ding, Yun[1];Hu, Aiguo[1]

机构：[1]East China Univ Sci & Technol, Sch Mat Sci & Engn, Shanghai Key Lab Adv Polymer Mat, Shanghai 200237, Peoples R China

年份：2018

卷号：7

期号：10

起止页码：2076

外文期刊名：ASIAN JOURNAL OF ORGANIC CHEMISTRY

收录：;WOS:【SCI-EXPANDED(收录号:WOS:000447542200017)】；

基金：The finacial supports from National Natural Science Foundation of China (21474027, 21503078), Shanghai Leading Academic Discipline Project (B502) are greatly acknowledged. AH thanks the "Eastern Scholar Professorship" support from Shanghai Local Government.

语种：英文

外文关键词：Bergman cyclization; cycloaddition; radicals; X-ray diffraction; density functional calculations

摘要：Enediyne compounds undergo Bergman cyclization while being activated with thermal or UV-light triggers, and generate benzyne diradical intermediates, endowing their great potential as antitumor agents. The radical nature of the Bergman cyclization is generally confirmed through radical trapping experiments. While using phenyl tert-butyl nitrone (PBN) as a radical trapping agent to study the Bergman cyclization of maleimide-based enediyne compounds, we uncovered concurrent radical addition and [3+2] cycloaddition reactions between nitrones and enediyne compounds. The radical addition between the diradical intermediates and PBN was revealed through EPR analysis, while the [3+2] cycloaddition products were separated out and their structures were confirmed by NMR, HRMS and single crystal XRD analysis. Computational investigations showed that the energy barrier of the [3+2] cycloaddition was much lower than that of the Bergman reaction, corroborating the dominance of [3+2] cycloaddition between nitrone and enediyne compounds.