Simple Resolution of Enantiomeric NMR Signals of α‐Amino Acids by Using Samarium(III) Nitrate With L‐Tartarate

Abstract

Readily available L-tartaric acid, which is a bidentate ligand with two chiral centers forming a seven-membered chelate ring, was applied to the chiral ligand for the chiral nuclear magnetic resonance (NMR) shift reagent of samarium(III) formed in situ. This simple method does not cause serious signal broadening in the high magnetic field. Enantiomeric (13)C and (1)H NMR signals and enantiotopic (1)H NMR signals of α-amino acids were successfully resolved at pH 8.0 and the 1:3 molar ratio of Sm(NO3)3:L-tartaric acid. It is elucidated that the enantiomeric signal resolution is attributed to the anisotropic magnetic environment for the enantiomers induced by the chiral L-tartarato samarium(III) complex rather than differences in stability of the diastereomeric substrate adducts. The present (13)C NMR signal resolution was also effective for the practical simultaneous analysis of plural kinds of DL-amino acids.

A universal strategy for visual chiral recognition of α-amino acids with l-tartaric acid-capped gold nanoparticles as colorimetric probes

“…As a readily available and cheap chiral molecule, L-TA is often regarded as a chiral selector to separate various enantiomers, [21][22][23] including many amino acids. 24,25 Very recently, we easily modified L-TA on the surface of AuNPs to obtain L-TA-capped AuNPs, and L-TA-capped AuNPs exhibited good capability of chiral recognition for mandelic acid in aqueous solution. 26 Based on these findings, [24][25][26] we hypothesize that L-TA-capped AuNPs can be used as colorimetric probes for chiral recognition of α-amino acids.…”

Significance and challenges of stereoselectivity assessing methods in drug metabolism

“…The first applies chiral derivatizing agents (CDAs), which can transform enantiomers into stable diastereomeric derivatives [111] . The second uses the chiral lanthanide shift reagent (LSRs), which can interact with enantiomers and form coordination compounds [112] . The third employs certain chiral solvating agents (CSAs), which can transform enantiomers into diamagnetic and instable diastereomers [113] .…”

Enantiomeric NMR signal separation behavior and mechanism of samarium(III) and neodymium(III) complexes with (S,S)‐ethylenediamine‐N,N'‐disuccinate

“…Whitesides and Lewis introduced the tris(camphorato) europium(III) complex as the first chiral lanthanide shift reagent. 20 On the other hand, more elaborate lanthanide complexes with chiral crown ether derivatives, 21,22 a chiral macrocyclic nitrogendonor ligand, 23 and pendant aminocyclodextrin hosts 24,25 were devised. Aqueous lanthanide(III) shift reagents were also extensively developed by using multidentate amine derivative ligands [7][8][9][10][11][12][13][14][15][16][17][18] and simple bidentate α-hydroxycarboxylates 19 and L-tartarate.…”

“…Aqueous lanthanide(III) shift reagents were also extensively developed by using multidentate amine derivative ligands [7][8][9][10][11][12][13][14][15][16][17][18] and simple bidentate α-hydroxycarboxylates 19 and L-tartarate. 20 On the other hand, more elaborate lanthanide complexes with chiral crown ether derivatives, 21,22 a chiral macrocyclic nitrogendonor ligand, 23 and pendant aminocyclodextrin hosts 24,25 were devised. Although correlation between relative magnitude of lanthanide-induced shifts for enantiomers and their absolute configurations is limited to closely related substrates, some absolute configurational assignments have been accomplished.…”