Norephedrine, determination

A-trityl-(l/ ,2S)-norephedrine (58), the corresponding allyl phosphonates 62a,b were obtained via the Arbusov rearrangement of 2-ethoxy-1,3,2-oxazaphospholidine 60. The absolute configuration of the major diastereomer, 62a was determined by X-ray as (2S1,45,51 ).The reaction of the major diastereomer of allyl phosphonates 61a and 62a with DBU afforded the corresponding vinylphosphonates 63a,b (Scheme 21) [48], Nucleophilic addition to these resulted in induction of chirality at the [1-position of the stereogenic phosphorus atom in the initially produced diastereomeric phosphonates 64 or 65 (Scheme 21) [48],... 

NMR probe75. It is derived from d-norephedrine and may be used to derivatize chiral acids and determine optical purities of asymmetric centers as far away as nine atoms from the selenium atom12. 

Silicon Gum SE-30 on Chromosorb-G Helium Thermal conducting Applied for simultaneous determination of dextromethorphan, chlorpheniramine norephedrine and salicylamide. (61)... 

F. T. Noggle, J. De Ruiter, and C. R. Clark, Liquid chromatographic determination of the enantiomeric composition of amphetamine prepared from norephedrine and norpseudoephedrine, J. Chromatogr. Sci., 25 38 (1987). 

As the boron enolate from dicyclohexylboron triflate and triethylamine at -78° C was determined to be an -isomer, the predominant formation of anti -aldol product can be explained via the classic Zimmerman-Traxler six-membered chairlike transition state3 (Scheme 2.2d). In transition state A, the norephedrine unit of the boron enolate presumably arranges itself in such a way that the phenyl group directs the approach of the aldehyde.4... 

Sagara K, Oshima T, Misaki T. A simultaneous determination of norephedrine, pseudoephedrine, ephedrine and methylephedrine in Ephedrae Herba and oriental pharmaceutical preparations by ion-pair high-performance liquid chromatography. Chem Pharm Bull (Tokyo) 1983 31(7) 2359-2365. 

Ephedrine and pseudoephedrine have been measured in guinea pig plasma using HPLC with fluorescence detection, following precolumn derivatization with 5-dimethylamino-napthalene-1-sulfonyl chloride in acetonitrile. The mobile phase was 0.6% phosphate buffer (pH 6.5)-methanol (3 8 v/v). Jacob et al. developed an LC-atmospheric pressure chemical ionization MS-MS method for the quantitaion of various alkaloids found in ephedra-containing dietary supplements and also in plasma and urine from subjects using these supplements. Using this method, the concentrations of ephedrine, pseudoephedrine, norephedrine, norpseudoephedrine, methylephedrine, methylpseudoephedrine and caffeine were determined in low nanogram quantities in plasma and urine. The analytical cycle time for this method was 12 min. 

Chicharro M, Zapardiel A, et al. Direct determination of ephedrine and norephedrine in human urine by capillary zone electrophoresis. J Chromatogr 1993 8,622 103-108. 

The bicyclic 1,3,2-dioxaphosphorinanes have lost their popularity and have been replaced, both for mechanistic studies and for synthetic purposes, by the monocyclic and yet diastereoisomeric 3,4-dimethyl-5-phenyl-l,3,2-oxazaphospholidines . The most widely employed of these compounds have been those derived from (-)-ephedrine and of 4S,5R geometry (79), from (+)-ephedrine, and so of 4R,5S geometry, and from (+)-pseudoephedrine, which are of structure 83 with 4S,5R stereochemistry. Their syntheses with a dichloride RP(Z)Cl2 in the presence of an appropriate HCl acceptor yield mixtures of products, epimeric at phosphorus, and generally separable. A few other compounds have been derived from norephedrine. The stereochemistries of several such compounds have been determined by X-ray crystallography, and reference has just been made to some... 

The biotransformation of ephedrine proceeds via demethylation to norephedrine and via oxidative deamination followed by conjugation, in analogy to the metabolism of amphetamine. Over 90% is eliminated via the kidneys within 24 h, up to 75% unchanged, 8-20% as norephedrine and the rest after oxidative deamination. Methylephedrine is 33% unchanged and is 8% excreted as ephedrine. The excretion rate also depends on the pH of the urine. Desmethylpropylhexedrine and 4-hydroxypropylhexedrine, metabolites of propylhexedrine, can be determined in the urine [44]. Prolintane, a benzylbutylpyrrolidine product, is to some extent changed oxidatively in the liver. This mainly produces hydroxylated metabolites, but also produces... 

In the meantime, [2,3- C2] pyruvic acid was fed to the stems of E. gerardiana for 5 days, and after cultivation for a further 2 days the aboveground parts were harvested. Ephedrine and related alkaloids were extracted, and it was determined by nuclear magnetic resonance that the proportions of ephedrine, norephedrine, pseudoephedrine, and norpseudoephed-rine were 35 3 52 10, respectively. 

Sporkert, E, et al. "Determination of Cathinone, Cathine and Norephedrine in Hair of Yemenite Khat Cheweis." Forensic Science International, 133 2003,39-46. 

Kaddoumi, A. Kubota, A. Nakashima, M.N. Takahashi, M. Nakashima, K. High performance liquid chromatography with UV detection for the simultaneous determination of sympathomimetic amines using 4-(4,5-diphenyl-lH-imidazole-2-yl)benzoyl chloride as a label, Biomed.Chromatogr., 2001, 15, 379-388. [human rat plasma derivatization LOD 50-100 nM ephedrine norephedrine 2-phenylethylamine fenfluramine phentermine cyclohexylamine fluoxetine is internal standard pharmacokinetics]... 

Kaddoumi, A. Nakashima, M.N. Nakashima, K. Fluorometric determination of DL-fenfluramine, DL-norfenfluramine and phentermine in plasma by achiral and chiral high-performance liquid chromatography, J.Chromatogr.B, 2001, 763, 79-90. [fluorescence detection derivatization human rat LOD 10 nM ephedrine norephedrine]... 

Fresh leaves of the khat bush Catha edulis Forssk.), found for example in several Afiican countries and the Arabian Peninsula, are chewed for their psychostimulant properties and evidence suggests that khat use may predate coffee drinking. The consumption of fresh leaves is based on the fact that potency diminishes drastically within two days. Correspondingly, khat use has remained endemic, but modem transportation allows for daily shipments to a variety of European countries and the United States. A large number of P-phenylethylamine derivatives have been detected but the main constituents are (S)-cathinone, (lS,2S)-cathine and (lR,2S)-norephedrine. Psychoactivity is, however, predominantly determined by cathinone and cathine (Fig. 18.6). The plant material is legally available in some countries, whereas both cathinone and cathine are controlled. (R)-cathinone has yet to be detected in leaves. 

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