R-VAPOL-phosphoric acid based¹H and¹³C-NMR for sensing of chiral amines and acids

Abstract

R-VAPOL-chiral solvating agent for discrimination of chiral amines and acids using 1H and 13C NMR.

Argentivorous Molecules Exhibiting Highly Selective Silver(I) Chiral Enhancement

“…In the 1 H NMR spectra of silver­(I) complexes with chiral L ligands, two sets of doublets for methyl protons from the two diastereomers were observed. , By contrast, ( S )- L 1 showed one doublet for the methyl protons, which indicated that diastereomers did not form.…”

Enantioselective Recognition of Racemic Amino Alcohols in Aqueous Solution by Chiral Metal‐Oxide Keplerate {Mo132} Cluster Capsules

“…Enantiopurity of amino alcohols is important in this context as (S)-propranolol is an active beta-blocker, whereas the (R)-isomer is ineffective in this application but has utility as a potential contraceptive. [24] A universal noncovalent chiral shift reagent for the determination of relative configuration by NMR spectroscopy does not exist and the chiral recognition of amino alcohols has been achieved using several chiral shift reagents, including arylcarboxylic acids, [25][26][27] atropisomers, [28] calixarenes/ resorcinarenes, [29][30][31][32][33][34][35][36] cyclodextrins, [37] crown ethers, [38][39][40] phosphorous-containing reagents, [41][42][43][44] and metallocomplexes, [45,46] amongst others. [47][48][49][50] The separation of amino alcohols has been almost exclusively limited to organic solvents except for resorcinarene and cyclodextrin hosts which have displayed separation in aqueous media.…”

A simple protocol for determination of enantiopurity of amines using BINOL derivatives as chiral solvating agentsvia1H- and19F-NMR spectroscopic analysis

“…The determination of enantiopurity via NMR spectroscopy required the presence of a chiral auxiliary to convert the enantiomers into diastereomers. The most commonly used chiral auxiliaries are chiral solvating agents {CSAs like tyrosine-modied pillar [5] arenes, R-VAPOL-phosphoric acid, organic-soluble acids, benzene tricarboxamide-based hydrogelators, BINOL phosphoric acid, Kagan's amides, roof-shape amines, BINOL and its derivatives}, [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] chiral derivatizing agents {CDAs like D-[Ir(ppy) 2 (MeCN) 2 ](PF 6 ) (ppy is 2-phenylpyridine), a-methoxy-aphenylacetic acid (MPA), a-methoxy-a-triuoromethylphenylacetic acid (MTPA) and BINOL}, [31][32][33][34][35][36] chiral lanthanide shi reagents {CLSRs like [Eu(tfc) 3 ], [Eu(hfc) 3 ], [Sm(tfc) 3 ], and [(R)-Pr(tfc) 3 ]}. [37][38][39] Among all the chiral auxiliaries reported for NMR chiral recognition, BINOL and its derivatives represent a useful auxiliary because of their direct utilization as a CSA.…”