Cytochrome P450s and Galactose Oxidases exploit redox active ligands to form reactive high valent intermediates for oxidation reactions. This strategy works well for the late 3d metals where accessing high valent states is rather challenging. Herein, we report the oxidation of Ni II (salenwith mCPBA (meta-chloroperoxybenzoic acid) to form a fleeting Ni III bisphenoxyl diradical species, in CH 3 CN and CH 2 Cl 2 at À 40 °C. Electrochemical and spectroscopic analyses using UV/Vis, EPR, and resonance Raman spectroscopies revealed oxidation events both on the ligand and the metal centre to yield a Ni III bisphenoxyl diradical species. DFT calculations found the electronic structure of the ligand and the dconfiguration of the metal center to be consistent with a Ni III bisphenoxyl diradical species. This three electron oxidized species can perform hydrogen atom abstraction and oxygen atom transfer reactions.
Haloperoxidase enzymes utilize metal hypohalite species to halogenate aliphatic and aromatic C–H bonds to C–X (X = Cl, Br, I) in nature. In this work, we report the synthesis and...
Cytochrome P450s and Galactose Oxidases exploit redox active ligands to form reactive high valent intermediates for oxidation reactions. This strategy works well for the late 3d metals where accessing high valent states is rather challenging. Herein, we report the oxidation of Ni II (salenwith mCPBA (meta-chloroperoxybenzoic acid) to form a fleeting Ni III bisphenoxyl diradical species, in CH 3 CN and CH 2 Cl 2 at À 40 °C. Electrochemical and spectroscopic analyses using UV/Vis, EPR, and resonance Raman spectroscopies revealed oxidation events both on the ligand and the metal centre to yield a Ni III bisphenoxyl diradical species. DFT calculations found the electronic structure of the ligand and the dconfiguration of the metal center to be consistent with a Ni III bisphenoxyl diradical species. This three electron oxidized species can perform hydrogen atom abstraction and oxygen atom transfer reactions.
The synthetic utility of proline‐catalyzed asymmetric α‐hydroxylation and subsequent reductive amination of aldehydes to afford chiral β‐amino alcohols is explored for the first time. Stereoselective synthesis of orthogonally protected 5‐hydroxylysine, 4‐hydroxyornithine and 2,4‐diamino‐3‐hydroxybutanoic acid was achieved. (2S,5S)‐5‐Hydroxylysine synthesized in this way was converted into the aminocaprolactam ring system of bengamide A.
Inspired by copper-based metalloenzymes, we aim to incorporate amino acids into our ligands to facilitate active copper intermediates that serve as functional and structural models for these enzymes. Herein, we...
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