Y-Ephedrine

Salts of 2-carboxyphenoxatellurin with nor- /-y -ephedrine, strychnine, cinchonidine, quinine, and J-a-phenylethylamine were prepared with the hope of resolving 2-carboxyphenoxatellurin into optically active isomers. 2-Carboxyphenoxatellurin samples regenerated from these salts did not have optical activity1. 

Propiophenone. Propiophenone [93-55-0] (ethyl phenyl ketone) is a colorless Hquid with a flowery odor. It can be prepared by the Friedel-Crafts reaction of benzene and propionyl chloride in the presence of aluminum chloride (346), or by the catalytic reaction of benzoic acid and propionic acid in the presence of water (347). Propiophenone is commercially available (348), and is sold in Japan at 2700 Y/kg (349). It is used in the production of ephedrine, as a fragrance enhancer, and as a polymerization sensitizer. 

An alternative approach to hydroboration has utilized a chiral B-H source with either achiral or chiral rhodium complexes.58 The enantiomerically pure reagent (21) is derived from ephedrine. Notably in the reactions with BINAP, a higher enantiomeric excess is produced from (R)-BINAP (6) compared to the Y-form (Scheme 13). 

Starting from the Pt-cinchona modified system, more recently an interesting concept has been developed by Feast and coworkers [144], A chiral acidic zeolite was created by loading one molecule of iM,3-dithianc-l-oxide per supercage of zeolite Y, either during or after the zeolite synthesis. Other chiral zeolites were formed by adsorbing ephedrine as a modifier on zeolites X and Y for the Norrish-Yang reaction [145],... 

High degrees of enantioselectivity have been observed when alkylzinc reagents react with aldehydes in the presence of chiral ligands.120 Among several compounds that have been used as ligands are exo - (dime th y I a m i no )no rb o rn c o I (A)121 122 123 124 and diphenyl(l-methyl-pyrrolin-2-yl)methanol (B) as well as ephedrine derivatives C and D. 

Pig liver esterase (PLE, E.C. 3.1.1.1) is one of the most successful enzymes for the enantiotopos-differentiating hydrolysis of dicarboxylic diesters and diacetates of diols as exemplified by the two examples, dimethyl cv. y-4-cydohexene-l,2-dicaiboxylate (I)100 - " 2 and (l/ ,2.S,3S)-l,3-di-acetoxy-2-nitrocyclohexane (3)113. The monoester 2 is obtained with the same results when prepared on a 100 mol scale114. The ee values of the monoester 2 may be determined conveniently by H-NMR spectroscopy in the presence of (+)- or ( )-ephedrine and that of the monoacetate 4, after conversion to the corresponding Mosher ester, by 19F-NMR spectroscopy. 

Alkylated /V- (l/ , 2.y )-2-Hydroxy-l-methyl-2-phenylethyl -/V-niethylalkananiides (Alkylated /V-Acyl-ephedrines, 3/4) General Procedure2 ... 

D. J. McConnell. 1998. Ephedra species in vitro culture, micropropagation, and the production ephedrine and other alkaloids. In Bajaj, Y. P. S. (ed.). Biotechnology in Agriculture and Forestry 41. Medicinal and Aromatic Plants X. Springer-Verlag. New York. p. 154-193. 

Another type of chiral Michael acceptor, the oxazepine derivatives (47), is prepared by condensation of the (-)-ephedrine-derived malonic acid derivative (46) with aldehydes (Scheme 18).51 52 Treatment of (47) with a variety of Grignard reagents in the presence of NiCh affords, after hydrolysis and decarboxylation, the 3-substituted carboxylic acids (48), in most cases with more than 90% ee. Diastereoselective Michael additions to (47) were also used for the preparation of optically active cyclopropane derivatives (49)53 and P-substituted-y-butyrolactones (50 Scheme 18).54 A total synthesis of indolmycin is based on this methodology.55... 

Ephedrine is the pharmacologically active enantiomers of ephe-drine. The enantiopurity tests for (-)-ephedrine can be performed using a peroctylated y-cyclodextrin based plastic membrane electrode [26], Bis (l-butylpentyl)adipate (BBPAP) was used as plasticizer and 10 3 mol/L NH4C1 as inner solution. The slope of the electrode is 60 mV/decade of concentration, and the potentiometric enantioselectivity coefficient is less than 10 4 The limit of detection is of 10 7 mol/L magnitude order. 

Upon irradiation of alkene 103 in a dye-exchanged zeolite Na-Y in the presence of a chiral media [(+)-ephedrin] and molecular oxygen, a small enantioselectiv-ity of 15% enantiomeric excess (ee) was found. This first experiment of an asymmetric ene photo-oxygenation reaction within the zeolite cavity is interesting, promising, and merits further investigation. 

Figure 9.1 Chromatogram of chiral separation of (1) norephedrine, (2) ephedrine, (3) cathinone, (4) amphetamine, (5) pseudoephedrine, (6) methcathinone, and (7) methamphetamine on S-folded separation channel (160 mm length) using 50 mM phosphate buffer (pH 7.35) with 10 mM HS-y-cyclodextrin and 5mM SDS at 8 kV/cm potential [18].

A combination of ( ) -/V- ben zy loxycarbon y I am i no acid (Z-amino acid) and ( )-ephedrine is a good example of one method of affording four diastereomers efficiently if seed crystals of less-soluble salt are obtained in advance (Figure 13). 

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