Electrochemical Transformations of Chiral Ni(II) Schiff Base Derivative of Serine: A Route to Novel Structures

Abstract Electrochemical oxidative functionalization of ( R )‐ and ( S )‐SerNi complexes performed in a biphasic H 2 O, NaBr, NaHCO 3 /CH 2 Cl 2 system using TEMPO as a mediator results in the formation of a new glycine derivative brominated at the α‐amino acid carbon as well as at the para ‐position of the aminophenylene ring in 70 % yield. The reaction is stereoselective; only the ( S )‐diastereomer is formed, regardless of the stereo configuration of the starting complex, which can be either ( S )‐ or ( R )‐SerNi. The lability of the C α ‐−C β bond in SerNi precludes targeted oxidation of the hydroxy group in the carbonyl derivative even under the mild conditions. Meanwhile, a new dibrominated complex with a labile C α ‐Br bond (BDE is 27 kcal/mol) is a convenient precursor for further modification of the amino acid fragment, for example via nucleophilic reactions. The new α‐sulfanyl complex was obtained in 63 % yield. The mechanism of the electrochemical processes is discussed.