Effect of substituents on the configurational stability of the stereogenic nitrogen in metal(II) complexes of α‐amino acid Schiff bases
Résumé
Herein, we report a general method for quantitative measurement of the con-figurational stability of the stereogenic nitrogen coordinated to M (II) in the corresponding square planar complexes. This stereochemical approach is quite sensitive to steric and electronic effects of the substituents and shown to work well for Ni(II), Pd(II), and Cu(II) complexes. Structural simplicity of the compounds used, coupled with high sensitivity and reliability of experimental procedures, bodes well for application of this approach in evaluation of chemical stability and stereochemical properties of newly designed chiral ligands for general asymmetric synthesis of tailor-made amino acids. KEYWORDS amino acids, chiral HPLC, kinetic of racemization, metal(II) complexes, Schiff bases, stereogenic nitrogen 1 | INTRODUCTION Tailor-made amino acids (AAs), 1 are essential structural features of numerous modern pharmaceuticals. 2 Application of AA residues in drug design allows for fairly accurate 3-D positioning of pharmacophoric moieties and mimicking the targeted biogenic peptide−receptor interactions. 3 Thus, over the past decade, about 20% of newly introduced drugs contained at least one tailor-made AA residue. 2 Consequently, the development of synthetic methodology for preparation of tailor-made AAs is currently in very high demand. 4 Following our long-standing interest in synthesis of sterically constrained 5 and fluorine-containing AAs, 6 we were actively contributing to the general asymmetric synthesis of α-AAs via Ni(II) complexes of AA Schiff bases (Scheme 1). 7
Domaines
Chimie de coordination
Origine : Fichiers produits par l'(les) auteur(s)
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