- Chiral separations of some β-adrenergic agonists and antagonists on AmyCoat column by HPLC
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Sixteen β-adrenergic antagonists namely acebutalol, alprenolol, atenolol, bisoprolol, bopindolol, bufurolol, carazolol, celiprolol, indenolol, metaprolol, nebivolol, oxprenolol, practolol, propranolol, tertalol, and timolol, and two β-adrenergic agonists namely cimeterol and clenbuterol were resolved on AmyCoat (150 x 46 mm, 3 μm size of silica particle) by using (85:15:0.1, v/v/v), (90:10:0.1, v/v/v), and (95:05:0.1, v/v/v) combinations of η-heptane, ethanol, and diethylamine solvents, respectively. The flow rates used were 0.5, 1.0, 2.0, and 3.0 ml/min with detection at 225 nm. The values of capacity, separation, and resolution factors ranged from 0.38 to 19.70, 1.08-2.33, and 1.0 and 4.50, respectively. The maximum and minimum resolutions were achieved for celiprolol and bufurolol, respectively. The chiral recognition mechanisms were also discussed. The values of validation parameters were calculated.
- Ali, Imran,Saleem, Kishwar,Gaitonde, Vinay D.,Aboul-Enein, Hassan Y.,Hussain, Iqbal
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experimental part
p. 24 - 28
(2010/09/14)
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- Asymmetric synthesis of aryloxypropanolamines via OsO4-catalyzed asymmetric dihydroxylation
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A simple and effective procedure for the enantioselective synthesis of several β-adrenergic blocking agents incorporating the first asymmetric synthesis of celiprolol, is described. The key steps are (i) sharpless asymmetric dihydroxylation of aryl allyl ethers to introduce chirality into the molecules and (ii) conversion of cyclic sulfates into the corresponding epoxides using a three-step procedure.
- Sayyed, Iliyas A.,Thakur, Vinay V.,Nikalje, Milind D.,Dewkar, Gajanan K.,Kotkar,Sudalai
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p. 2831 - 2838
(2007/10/03)
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- Determination of the enantiomeric purity and the configuration of β- aminoalcohols using (R)-2-fluorophenylacetic acid (AFPA) and fluorine-19 NMR: Application to β-blockers
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A method has been developed for determining the enantiomeric purity and the absolute configuration of β-aminoalcohols of type ArOCH2CH(OH)CH2NHR (R = iPr, tBu). To determine enantiomeric purity, the amine function was first protected by a benzyl group, then the compound formed was esterified using the acid chloride of (R)-2-fluorophenylacetic acid (AFPA). The 19F NMR analysis of the derivative obtained revealed the presence of two distinctly separate signals (~2.5 ppm), the one for the RS-SR pair being the most deshielded. The configuration was determined directly on the aminoalcohol by using the acid. In stoichiometric conditions, when R = iPr, the amide function was obtained very preponderantly. The 19F NMR spectrum of the amide presented four distinct signals when derivatization was carried out by means of a reaction between the (±)-β-aminoalcohol and the (R)-AFPA. The extreme signals, which were over 3.5 ppm apart, did not belong to the same diastereomer. With R = tBu essentially the ester function was obtained. The first studies revealed the presence of two signals, though not as clearly separated as in the previous cases. Each experiment was simple to perform, and purification was not necessary. Mosher's acid gave unsatisfactory results in each case. (C) 2000 Elsevier Science Ltd.
- Apparu, Marcel,Ben Tiba, Younes,Leo, Pierre-Marc,Hamman, Sylvain,Coulombeau, Christian
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p. 2885 - 2898
(2007/10/03)
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- Enantioselective ring opening of epoxides with trimethylsilyl azide (TMSN3) in the presence of β-cyclodextrin: An efficient route to 1,2-azido alcohols
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The ring opening of epoxides with nucleophiles such as TMSN3 and isopropylamine takes place enantioselectively in the presence of β- cyclodextrin under extremely mild conditions and the azido alcohols and amino alcohols are formed as (S)-isomers. (C) 1999 Published by Elsevier Science Ltd.
- Kamal, Ahmed,Arifuddin,Rao, Maddamsetty V.
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p. 4261 - 4264
(2007/10/03)
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- Enzyme Catalyzed Stereoselective Synthesis of (S)-Propanolamines
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Stereoselective synthesis of (S)-propanolamines has been carried out by the ring opening of racemic epoxides with 2-propylamine in presence of lipases and subtilisin.The effect of solvent towards selectivity has also been studied.
- Kamal. Ahmed,Rao, Maddamsetty V.
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p. 1881 - 1882
(2007/10/02)
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- Enzyme Assisted Preparation of Enantiomerically Pure β-Adrenergic Blockers III. Optically Active Chlorohydrin Derivatives and Their Conversion
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Optical active chlorohydrin derivatives 2a-m and 3a-m of both enantiomeric series were prepared via both enzymatic hydrolyses and acyltransfer reactions catalysed by a highly selective lipase from Pseudomonas sp..The resulting building blocks were further transformed into the corresponding β-blockers of high enantiomeric purity.
- Ader, Ulrich,Schneider, Manfred P.
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p. 521 - 524
(2007/10/02)
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- STEREOSELECTIVE SYNTHESIS OF (S)-PROPANOL AMINES: LIPASE CATALYZED OPENING OF EPOXIDES WITH 2-PROPYLAMINE
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The ring opening of epoxides with 2-propylamine in presence of lipase in organic solvents affords selectively (S)-propanol amines.The effect of solvents towards selectivity has also been examined.
- Kamal, Ahmed,Damayanthi, Yalamati,Rao, Maddamsetty V.
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p. 1361 - 1364
(2007/10/02)
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- Synthesis and β-Adrenergic Antagonist Activity of Stereoisomeric Practolol and Propranolol Derivatives
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A series of stereoisomeric practolol and propranolol derivatives has been synthesized in which the N-isopropyl group of the drug was replaced by an asymmetric heptanoic acid terminated by a substituted p-toluidide of p-(tri-fluoromethyl)anilide.The asymmetric epoxide, 3-(p-acetamidophenoxy)-1,2-epoxypropane, was allowed to react with a preformed enantiomeric 6-aminoheptanoic acid amide to yield the stereoisomeric practolol congener derivatives.An asymmetric drug precursor epoxide was prepared from p-acetamidophenol and enantiomeric 3-(tosyloxy)-1,2-epoxypropane (the Sharpless epoxide).For the propranolol congener derivatives, the preformed asymmetric 6-aminoheptanoic acid amides were allowed to react with one of the enantiomers of 3-(1-naphthyloxy)-1,2-epoxypropane.This drug precursor epoxide was prepared either by combining 1-naphthol with enantiomeric 3-(tosyloxy)-1,2-epoxypropane (the Sharpless epoxide) or by combining 1-naphthol with enantiomeric 3-(tosyloxy)-1,2-propanediol followed by epoxidation.Pharmacological studies carried out for the practolol derivatives demonstrated a significant dependence of enhanced potency and tissue/subreceptor specificity on both the configuration of the drug asymmetric carbon and the configuration of the spacer asymmetric carbon.The compounds containing the S configuration at the drug asymmetric center and the R configuration at the spacer asymmetric carbon exhibited an increase in potency over the other stereoisomeric congener derivatives and the progenitor drug.For the propranolol congener derivatives, a large decrease in potency was observed for all of the stereoisomers over the progenitor drug.The propranolol stereoisomers containing the S configuration at the drug asymmetric center were more active than those containing the R configuration at that center.
- Leftheris, Katerina,Goodman, Murray
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p. 216 - 223
(2007/10/02)
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