Axially chiral Ni(II) complexes of α‐amino acids: Separation of enantiomers and kinetics of racemization |
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| Authors: | Wenzhong Zhang Romuald Eto Ekomo Christian Roussel Hiroki Moriwaki Hidenori Abe Jianlin Han Vadim A Soloshonok |
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| Institution: | 1. School of Chemistry and Chemical Engineering, State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing, China;2. Aix Marseille Univ, CNRS, Centrale Marseille iSm2, Marseille, France;3. Hamari Chemicals Ltd, Osaka, Japan;4. Department of Organic Chemistry I, Faculty of Chemistry, University of the Basque Country UPV/EHU, San Sebastián, Spain;5. IKERBASQUE, Basque Foundation for Science, Bilbao, Spain |
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| Abstract: | Herein we present design, synthesis, chiral HPLC resolution, and kinetics of racemization of axially chiral Ni(II) complexes of glycine and di‐(benzyl)glycine Schiff bases. We found that while the ortho‐fluoro derivatives are configurationally unstable, the pure enantiomers of corresponding axially chiral ortho‐chloro‐containing complexes can be isolated by preparative HPLC and show exceptional configurational stability (t1/2 from 4 to 216 centuries) at ambient conditions. Synthetic implications of this discovery for the development of new generation of axially chiral auxiliaries, useful for general asymmetric synthesis of α‐amino acids, are discussed. |
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| Keywords: | amino acids axial chirality chiral HPLC kinetic of racemization rotational energy barriers |
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