Santiago João V, Orłowska Katarzyna, Ociepa Michał, Gryko Dorota
Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44, 5201-224 Warsaw, Poland.
Org Lett. 2023 Sep 1;25(34):6267-6271. doi: 10.1021/acs.orglett.3c02055. Epub 2023 Aug 22.
Diazo compounds with redox-active leaving groups are versatile reagents for orthogonal functionalizations, previously utilized in the Rh-catalyzed synthesis of highly substituted cyclopropanes. Photochemical activation of aryl-substituted diazoacetates generates carbenes, whereas redox-active esters can furnish C-radicals via the photoexcitation of EDA complexes. However, the photochemical behavior of these two functionalities, while present in one molecule, remains to be defined. We demonstrate that under light irradiation, reactions occur only on the diazo moiety, leaving the NHPI functionality intact. Not only aryl- but also alkyl-substituted NHPI diazoacetates are activated by blue light; either C-H insertion or the hydrogen/carbon 1,2-rearrangement occurs depending on the aryl/alkyl group.
带有氧化还原活性离去基团的重氮化合物是用于正交官能化的多功能试剂，此前已用于铑催化的高取代环丙烷的合成。芳基取代的重氮乙酸酯的光化学活化产生卡宾，而氧化还原活性酯可通过电子给体-受体（EDA）配合物的光激发提供碳自由基。然而，这两种官能团在一个分子中时的光化学行为仍有待确定。我们证明，在光照下，反应仅发生在重氮部分，而NHPI官能团保持完整。不仅芳基取代的NHPI重氮乙酸酯，而且烷基取代的NHPI重氮乙酸酯都能被蓝光活化；根据芳基/烷基的不同，会发生C-H插入或氢/碳1,2-重排。
