O‐nitromandelic acid: A chiral solvating agent for the NMR determination of chiral diamine enantiomeric purity

Abstract

O-Nitromandelic acid, easily prepared from either enantiomer of mandelic acid, has been used as a chiral solvating agent for the determination of enantiomeric purity of several diamine derivatives and other compounds using 1 H NMR spectroscopy. Chirality 9: 556-562, 1997.

Microwave‐Assisted Synthesis of (±)‐Mandelic Acid‐d5, Optical Resolution, and Absolute Configuration Determination

“…Generally, the so-called "mandelic acid effect" [11] induces nonequivalence in 1 H NMR signals of the aliphatic protons of the analytes. In several cases, however, also the aromatic protons of the chiral species under observation display good enantiodiscrimination [10,12,13]. us, it may be hypothesized that MA and derivatives perdeuterated on the phenyl rings could be useful CSAs for bad cases where ee values have to be determined for compounds devoid of singlets or doublets in a free high �eld region of their 1 H NMR spectra, and when the aromatic proton resonances of the CSA overlap the aromatic proton signals of the compound under study.…”

Determination of the enantiomeric composition of chiral delta‐2‐thiazolines‐1,3 by 1H and 19F NMR spectroscopy using chiral solvating agents

“…If the basic principles for use of CSAs have previously been intensively discussed in reviews compiling also their numerous applications in enantiomeric purity determination [19][20][21][22], considerable effort is still dedicated to the study of labile diastereomers and the preparation of more general and/or stronger CSAs [23][24][25][26][27].…”