Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200062, China.
Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200062, China.
J Am Chem Soc. 2023 Mar 8;145(9):4934-4939. doi: 10.1021/jacs.2c12155. Epub 2023 Feb 22.
Iron porphyrin carbenes (IPCs) have been extensively recognized as the reactive intermediates in various iron porphyrin-catalyzed carbene transfer reactions. While donor-acceptor diazo compounds have been frequently used for such transformations, the structures and reactivities of donor-acceptor IPCs are less explored. To date, no crystal structures of donor-acceptor IPC complexes have been reported, and therefore, the involvement of IPC intermediacy for such transformations lacks direct evidence. Here we report the synthesis and NMR characterization of several donor-acceptor IPC complexes from iron porphyrin and corresponding donor-acceptor diazo compounds. The X-ray crystal structure of an IPC complex derived from a morpholine-substituted diazo amide was obtained. The carbene transfer reactivities of those IPCs were tested by the N-H insertion reactions with aniline or morpholine as well as the three-component reaction with aniline and γ,δ-unsaturated α-keto ester based on electrophilic trapping of an ammonium ylide intermediate. Based on these results, IPCs were identified as the real intermediates for iron porphyrin-catalyzed carbene transfer reactions from donor-acceptor diazo compounds.
铁卟啉碳烯（IPCs）已被广泛认为是各种铁卟啉催化碳烯转移反应中的反应中间体。虽然供体-受体重氮化合物经常用于此类转化，但供体-受体 IPC 的结构和反应性研究较少。迄今为止，尚未报道供体-受体 IPC 配合物的晶体结构，因此，此类转化中涉及 IPC 中间体缺乏直接证据。在这里，我们报告了几种铁卟啉和相应的供体-受体重氮化合物衍生的供体-受体 IPC 配合物的合成和 NMR 表征。获得了衍生自吗啉取代的重氮酰胺的 IPC 配合物的 X 射线晶体结构。通过苯胺或吗啉的 N-H 插入反应以及基于铵叶立德中间体的亲电捕获的苯胺和γ，δ-不饱和α-酮酯的三组分反应测试了这些 IPC 的碳烯转移反应活性。基于这些结果，IPC 被鉴定为铁卟啉催化的碳烯转移反应从供体-受体重氮化合物中产生的真实中间体。
