Ephedrine enantiomeric purity

Limits of detection for many amino acids were enhanced considerably by pre-column derivatization with the achiral reagent dansyl chloride whose function it was to increase their specific rotation [17]. Determinations of the enantiomeric purities for mixtures of D-and L-tryptophan [18] and of isomeric ratios for mixtures of pseudoephedrine and its diastereomer ephedrine [19], were effected using diode-laser polarimetry and using OR detection in series with UV absorbance detection respectively. 

The reaction of racemic A-phthalimido-S-p-tolyl-S-vinylsulfoximine with a deficiency (0.5 molar equiv) of enantiomerically pure (-)-ephedrine resulted in a kinetic resolution of the vinyl sulfoximine.113 When the reaction was conducted at -30 °C the unreacted vinyl sulfoximine could be recovered with an enantiomeric purity of 46%. (-)-Amphetamine and (+)-l-phenylethylamine were not effective for kinetic resolution. The analogous (Z)-propenyl sulfoximine also underwent kinetic resolution with (-)-ephedrine, but the extent of kinetic resolution was not determined. 

Diastereoselective Alkylation and Reduction of Chiral Hydrazones Derived from Ephedrine. Methylmagnesium Bromide adds to the chiral hydrazone derived from V-aminoephedrine and benzaldehyde to afford the optically active chiral hydrazine in almost 100% de. Hydrogenolysis of the chiral hydrazine gives (/ )-a-phenylethylamine with more than 97% ee (eq 1). Ephedrine is recovered in good yield and without any loss of enantiomeric purity. 

Other Applications. Chiral oxazaborolidines derived from ephedrine have also been used in asymmetric hydroborations, and as reagents to determine the enantiomeric purity of secondary alcohols. Chiral l,3,2-oxazaborolidin-5-ones derived from amino acids have been used as asymmetric catalysts for the Diels-Alder reaction,and the aldol reaction. ... 

A new n.m.r. shift reagent, tris-[3-(t-butylhydroxymethylene)-d-camphorato]-europium(m), should prove to be useful for the determination of enantiomeric purity of chiral / -phen ethyl amines.2 For example, it was found that the CHNH2 resonances of (R)- and (S)-amphetamines were separated by 0.7 p.p.m. in a carbon tetrachloride solution of the europium reagent ( 0.15 mol 1 l. In comparison to the use of optically active solvents for the same purpose, this technique has the advantage of showing very large shifts between resonances of enantiomers. Mass spectrometry has been used in the detection of mescaline and tetrahydro-isoquinoline precursors as biochemical intermediates.3 Spectral differences of 4-chloro-2-nitrobenzenesulphonyl derivatives of ephedrine and related compounds have been used for identification purposes.4... 

Octylation of a- and 0-cyclodextrins has led to products carrying the alkyl groups at 0-2 and 6 and 2, 3 and 6. These were used in potentiometric electrodes to measure the enantiomeric purity of ephedrine in the presence of senun cations. A symposium has been held on related alkyl and alkylacyl cyclodextrin derivatives. ... 

Compounds such as methamphetamine 34, methcathi-none, and the precursor ephedrine are important in forensic analysis. Knowledge of the enantiomeric purity of these drugs can help in identifying their source. The enantiomeric purity of these drugs has been analyzed using BINOL as a... 

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