Chiral discrimination of secondary alcohols and carboxylic acids by NMR spectroscopy

Abstract

The manuscript reports two novel ternary ion-pair complexes, which serve as chiral solvating agents, for enantiodiscrimination of secondary alcohols and carboxylic acids. The protocol for discrimination of secondary alcohols is designed by using one equivalent mixture each of enantiopure mandelic acid, 4-dimethylaminopyridine (DMAP) and a chiral alcohol. For discrimination of carboxylic acids, the ternary complex is obtained by one equivalent mixture each of enantiopure chiral alcohol, DMAP and a carboxylic acid. The designed protocols also permit accurate measurement of enantiomeric composition.

NMR chiral discrimination of chalcogen containing secondary alcohols

“…By combining 1.0 equivalent of ( + )‐MTPA, ( + )‐MPA, ( + )‐mandelic acid, ( + )‐BINOL, or ( + )‐Naproxen with chalcogen alcohol 1a in CDCl 3 , the desired anisotropic effect was not observed in the 1 H and 125 Te‐{ 1 H} NMR spectra. Based on the formation of a ternary complex and to improve the intermolecular interactions, 1.0 equivalent of 4‐(dimethylamino) pyridine (DMAP) base was added to the medium with the CSA. In this protocol, the split signals in the 1 H NMR spectrum was observed only with ( + )‐BINOL/DMAP ternary complex.…”

“…Inversely, the ∆ δ RS value of the CH 3 group in deuterated benzene of the 1 H NMR increased. This type of result is difficult to predict and is caused by the anisotropic effect of the solvent . When deuterated pyridine was employed, the split signal decreased for the 125 Te‐{ 1 H} NMR spectrum and vanished for the 1 H NMR spectrum (Table , entries 3 and 4).…”

“…This type of result is difficult to predict and is caused by the anisotropic effect of the solvent. 21 When deuterated pyridine was employed, the split signal decreased for the 125 Te-{ 1 H} NMR spectrum and vanished for the 1 H NMR spectrum ( Table 3, entries 3 and 4). These results exalt the advantages of multinuclear NMR spectroscopy because of the substantial Δδ RS values and no overlapping of the signals.…”

Investigation of New Dihydropyridine Derivative Solutions by Using of 2d Dosy NMR

“…As well, NMR has important role at investigations of the formation of intermolecular complexes, association, self-organization, molecular recognition, reorientation and rearrangements of supramolecular structures under the action of various factors [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29]. Beside, NMR spectroscopy and its experimental equipment enable measurements of the self-diffusion coefficients (SDC) in the high-resolution mode, which in this case DOSY an important experimental method suitable for separation of the spectral contributions of different components of a system under study based on different sizes of the components.…”

Synthesis of a new 1,2,3,4,5-pentasubstituted cyclohexanol and determining its stereochemistry by NMR spectroscopy and quantum-chemical calculations

“…The NMR is a very important analytical method for identifying the structure of organic molecules and studies of dynamic processes in different solutions . We have applied NMR and quantum‐chemical calculations methods to the cyclohexane derivative of the chalcone 1 to obtain insight into the three‐dimensional structure of this system.…”