Measurement of the optical purity of fluorinated compounds using proton decoupled 19F NMR spectroscopy in a chiral liquid crystal solvent

Resolution enhancement in spectra of natural products dissolved in weakly orienting media with the help of 1H homonuclear dipolar decoupling during acquisition: Application to 1H–13C dipolar couplings measurements

“…The concentration of menthol was chosen so high to have excellent signal to noise while optimizing FF-HSQC. Details on the method and sample preparation can be found in literature [25]. All 5 mm O.D.…”

Improvements to selective refocusing phased (SERFph) experiments

“…It has been shown how this may be achieved by using a chiral liquid crystal as a solvent, and the most efficient solvents for this purpose are lyotropic liquid crystals obtained by dissolving a synthetic homopolypeptide such as poly-(c-benzyl)-L-glutamate (PBLG) or poly-(e-carbobenzoxy)-L-lysin (PCBLL) in a non-denaturing organic co-solvent (CHCl 3 , CH 2 Cl 2 , 1,4-dioxane, N,N-dimethylformamide etc.) [2][3][4][5][6][7][8]. In these chiral anisotropic solvents there is a difference in the diastereomeric interactions between the chiral solute and the oriented polypeptide fibers, which produces a difference in their orientational order [9].…”

“…In these chiral anisotropic solvents there is a difference in the diastereomeric interactions between the chiral solute and the oriented polypeptide fibers, which produces a difference in their orientational order [9]. Consequently, any anisotropic NMR interaction, such as the dipolar coupling, the chemical shift or the quadrupolar splitting for nuclear spins I > 1/2, are different for enantiomers [2][3][4][5][6][7]. Deuterium NMR has proved to be particularly effective in measuring enantiomeric excess by this method because of the simplicity of the spectra, which are dominated by the large quadrupolar interaction.…”

Chemical shift anisotropy edited complete unraveling of overlapped 1H NMR spectra of enantiomers: Application to small chiral molecules

“…The recent study also discusses the use of homo and heteronuclear two-dimensional methods to analyse a mixture of deuterated unlike and like stereo isomers [12]. There are also studies using 13 C [13,14] and 19 F [15,16]. In spite of severe overlap of the transitions, the proton detection is advantageous because of; (a) its high magnetic moment, (b) high natural abundance and (c) abundant presence in all the chiral organic molecules.…”