Application of [Co(Corrole)]– Complexes in Ring‐Closing C–H Amination of Aliphatic Azides via Nitrene Radical Intermediates. Issue 5 (25th January 2018)

• Record Type: Journal Article
• Authors: Goswami, Monalisa; Geuijen, Paul; Reek, Joost. N. H.; de Bruin, Bas
• Is Part Of: European journal of inorganic chemistry. Issue 5(2018)
• Page Start: 617
• Page End: 626
• Publication Date: 2018-01-25
• Subjects: Radicals -- Nitrogen heterocycles -- Macrocyclic ligands -- Cobalt -- Amination; Chemistry, Inorganic -- Periodicals; Organometallic chemistry -- Periodicals; Bioinorganic chemistry -- Periodicals; Solid state chemistry -- Periodicals; 546
• DOI: 10.1002/ejic.201701343
• Languages: English
• ISSNs: 1434-1948

Abstract

Abstract : The synthesis, characterisation and application of anionic [Co II (Cor)] – (Cor = corrole) metalloradicals in the ring‐closing C–H amination of an aliphatic azide in the presence of Boc2 O (Boc = tert ‐butyloxycarbonyl) to give the corresponding Boc‐protected N‐heterocyclic product tert ‐butyl 2‐phenylpyrrolidine‐1‐carboxylate are reported. This is the first example of the use of metalloradical cobalt(II) corrole complexes in nitrene‐transfer reactions. On the basis of DFT calculations, the reaction is proposed to proceed via discrete open‐shell nitrene radical intermediates bearing most of their spin density at the nitrene nitrogen atom. The [Co II (Cor)] – complexes are substantially faster catalysts than the corresponding neutral [Co II (porphyrin)] complexes when applied in the same ring‐closing C–H amination reaction under identical reaction conditions. Increasing the electron density at cobalt(II) therefore has a positive influence on the reaction rate. Abstract : Compared to porphyrins (Por), corroles (Cor) have one fewer carbon atom in the ring, and this leads to a smaller ring size and a trianionic ligand. This first study on [Co II (Cor)] – metalloradicals in the ring‐closing C–H amination of an aliphatic azide shows that they are substantially more active catalysts than the corresponding neutral [Co II (Por)] complexes.