title: Chiral discrimination of α-hydroxy acids and N-Ts-α-amino acids induced by tetraaza macrocyclic chiral solvating agents by using1H NMR spectroscopy.
abstract: In the field of chiral recognition, reported chiral discrimination by1H NMR spectroscopy has mainly focused on various chiral analytes with a single chiral center, regarded as standard chiral substrates to evaluate the chiral discriminating abilities of a chiral auxiliary. Among them, chiral α-hydroxy acids, α-amino acids and their derivatives are chiral organic molecules involved in a wide variety of biological processes, and also play an important role in the area of preparation of pharmaceuticals, as they are part of the synthetic process in the production of chiral drug intermediates and protein-based drugs. In this paper, several α-hydroxy acids and N-Ts-α-amino acids were used to evaluate the chiral discriminating abilities of tetraaza macrocyclic chiral solvating agents (TAMCSAs) 1a-1d by1H NMR spectroscopy. The results indicate that α-hydroxy acids and N-Ts-α-amino acids were successfully discriminated in the presence of TAMCSAs 1a-1d by1H NMR spectroscopy in most cases. The enantiomers of the α-hydroxy acids and N-Ts-α-amino acids were assigned based on the change of integration of the1H NMR signals of the corresponding protons. The enantiomeric excesses (ee) of N-Ts-α-amino acids 11 with different optical compositions were calculated based on the integration of the1H NMR signals of the CH3protons (Ts group) of the enantiomers of (R)- and (S)-11 in the presence of TAMCSA 1b. At the same time, the possible chiral discriminating behaviors have been discussed by means of the Job plots of (±)-2 with TAMCSAs 1b and proposed theoretical models of the enantiomers of 2 and 6 with TAMCSA 1a, respectively.
authors.affiliation: College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China. linai@bnu.edu.cn.
authors.forename: Caixia
authors.initials: C
authors.lastname: Lv
authors.forename: Lei
authors.initials: L
authors.lastname: Feng
authors.forename: Hongmei
authors.initials: H
authors.lastname: Zhao
authors.forename: Guo
authors.initials: G
authors.lastname: Wang
authors.forename: Pericles
authors.initials: P
authors.lastname: Stavropoulos
authors.forename: Lin
authors.initials: L
authors.lastname: Ai
mesh_terms: D000596:Amino Acids / Q000138:chemical synthesis / Q000737:chemistry*; D006880:Hydroxy Acids / Q000138:chemical synthesis / Q000737:chemistry*; D047028:Macrocyclic Compounds; D015394:Molecular Structure; D066244:Proton Magnetic Resonance Spectroscopy; D012995:Solubility
chemical_list: D000596:Amino Acids; D006880:Hydroxy Acids; D047028:Macrocyclic Compounds