Expanding the Family of Octahedral Chiral-at-Metal Cobalt(III) Catalysts by Introducing Tertiary Amine Moiety Into the Ligand

• Main Authors: Tat’yana F. Savel’yeva, Olga V. Khromova, Vladimir A. Larionov, Alexander F. Smol’yakov, Ivan V. Fedyanin, Yuri N. Belokon, Victor I. Maleev
• Format: Article
• Language: English
• Published: MDPI AG 2021-01-01
• Series: Catalysts
• Subjects: metal-templated complex; chirality; chiral-at-metal; cobalt(III); hydrogen bond donor; Schiff base
• Online Access: https://www.mdpi.com/2073-4344/11/2/152

Chiral metal-templated complexes are attractive catalysts for organic synthetic transformations. Herein, we introduce a novel chiral cobalt(III)-templated complex based on chiral <i>trans</i>-3,4-diamino-1-benzylpyrrolidine and 3,5-di-<i>tert</i>-butyl-salicylaldehyde which features both hydrogen bond donor and Brønsted base functionalities. The obtained complexes were fully characterized by ¹H, ¹³C NMR, IR-, UV-vis, CD-spectroscopy and by a single X-ray diffraction analysis. It was shown that chlorine anion is connected with amino groups of the complex via a hydrogen bonding. DFT calculations of charges and molecular electrostatic potential of the cobalt(III) complex showed that the basicity of the complex is certainly diminished as compared with the routine tertiary amines but the acidity of the conjugated acid of the complex should be increased. Thus, the catalytic potential of the complex may be much greater as a chiral acid than a chiral base. We believe that this work opens a new way in chiral bifunctional catalyst design.