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Updated: Aug 9, 2025

Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
Published on: April 19, 2019
Synthesis and Characterization of Donor-Acceptor Iron Porphyrin Carbenes and Their Reactivities in N-H Insertion and
Chaoqun Ma1, Shang Wang1, Yuan Sheng1
1Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200062, China.
Abstract:
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.
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