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Quantum chemistry of cocaine and its isomers II: spectroscopy. COMPUT THEOR CHEM 2022. [DOI: 10.1016/j.comptc.2022.113952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Kohnen-Johannsen KL, Kayser O. Tropane Alkaloids: Chemistry, Pharmacology, Biosynthesis and Production. Molecules 2019; 24:E796. [PMID: 30813289 PMCID: PMC6412926 DOI: 10.3390/molecules24040796] [Citation(s) in RCA: 113] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 02/15/2019] [Accepted: 02/18/2019] [Indexed: 12/18/2022] Open
Abstract
Tropane alkaloids (TA) are valuable secondary plant metabolites which are mostly found in high concentrations in the Solanaceae and Erythroxylaceae families. The TAs, which are characterized by their unique bicyclic tropane ring system, can be divided into three major groups: hyoscyamine and scopolamine, cocaine and calystegines. Although all TAs have the same basic structure, they differ immensely in their biological, chemical and pharmacological properties. Scopolamine, also known as hyoscine, has the largest legitimate market as a pharmacological agent due to its treatment of nausea, vomiting, motion sickness, as well as smooth muscle spasms while cocaine is the 2nd most frequently consumed illicit drug globally. This review provides a comprehensive overview of TAs, highlighting their structural diversity, use in pharmaceutical therapy from both historical and modern perspectives, natural biosynthesis in planta and emerging production possibilities using tissue culture and microbial biosynthesis of these compounds.
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Affiliation(s)
- Kathrin Laura Kohnen-Johannsen
- Technical Biochemistry, Department of Biochemical and Chemical Engineering, Technical University Dortmund, D-44227 Dortmund, Germany.
| | - Oliver Kayser
- Technical Biochemistry, Department of Biochemical and Chemical Engineering, Technical University Dortmund, D-44227 Dortmund, Germany.
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Basler B, Brandes S, Spiegel A, Bach T. Total Syntheses of Kelsoene and Preussin. Top Curr Chem (Cham) 2017. [DOI: 10.1007/b96880] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Fagan P, Kocourková L, Tatarkovič M, Králík F, Kuchař M, Setnička V, Bouř P. Cocaine Hydrochloride Structure in Solution Revealed by Three Chiroptical Methods. Chemphyschem 2017; 18:2258-2265. [DOI: 10.1002/cphc.201700452] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Revised: 05/31/2017] [Indexed: 11/11/2022]
Affiliation(s)
- Patrik Fagan
- Departments of Analytical Chemistry and Chemistry of Natural Compounds and Forensic Laboratory of Biologically Active Substances; University of Chemistry and Technology; Technická 5 16628 Prague Czech Republic
| | - Lucie Kocourková
- Departments of Analytical Chemistry and Chemistry of Natural Compounds and Forensic Laboratory of Biologically Active Substances; University of Chemistry and Technology; Technická 5 16628 Prague Czech Republic
| | - Michal Tatarkovič
- Departments of Analytical Chemistry and Chemistry of Natural Compounds and Forensic Laboratory of Biologically Active Substances; University of Chemistry and Technology; Technická 5 16628 Prague Czech Republic
| | - František Králík
- Departments of Analytical Chemistry and Chemistry of Natural Compounds and Forensic Laboratory of Biologically Active Substances; University of Chemistry and Technology; Technická 5 16628 Prague Czech Republic
| | - Martin Kuchař
- Departments of Analytical Chemistry and Chemistry of Natural Compounds and Forensic Laboratory of Biologically Active Substances; University of Chemistry and Technology; Technická 5 16628 Prague Czech Republic
| | - Vladimír Setnička
- Departments of Analytical Chemistry and Chemistry of Natural Compounds and Forensic Laboratory of Biologically Active Substances; University of Chemistry and Technology; Technická 5 16628 Prague Czech Republic
| | - Petr Bouř
- Institute of Organic Chemistry and Biochemistry; Academy of Sciences; Flemingovo náměstí 2 16610 Prague Czech Republic
- Departments of Analytical Chemistry and Chemistry of Natural Compounds and Forensic Laboratory of Biologically Active Substances; University of Chemistry and Technology; Technická 5 16628 Prague Czech Republic
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Activation of dormant secondary metabolite production by introducing neomycin resistance into the deep-sea fungus, Aspergillus versicolor ZBY-3. Mar Drugs 2014; 12:4326-52. [PMID: 25076061 PMCID: PMC4145319 DOI: 10.3390/md12084326] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2014] [Revised: 06/20/2014] [Accepted: 07/08/2014] [Indexed: 12/02/2022] Open
Abstract
A new ultrasound-mediated approach has been developed to introduce neomycin-resistance to activate silent pathways for secondary metabolite production in a bio-inactive, deep-sea fungus, Aspergillus versicolor ZBY-3. Upon treatment of the ZBY-3 spores with a high concentration of neomycin by proper ultrasound irradiation, a total of 30 mutants were obtained by single colony isolation. The acquired resistance of the mutants to neomycin was confirmed by a resistance test. In contrast to the ZBY-3 strain, the EtOAc extracts of 22 of the 30 mutants inhibited the human cancer K562 cells, indicating that these mutants acquired a capability to produce antitumor metabolites. HPLC-photodiode array detector (PDAD)-UV and HPLC-electron spray ionization (ESI)-MS analyses of the EtOAc extracts of seven bioactive mutants and the ZBY-3 strain indicated that diverse secondary metabolites have been newly produced in the mutant extracts in contrast to the ZBY-3 extract. The followed isolation and characterization demonstrated that six metabolites, cyclo(d-Pro-d-Phe) (1), cyclo(d-Tyr-d-Pro) (2), phenethyl 5-oxo-l-prolinate (3), cyclo(l-Ile-l-Pro) (4), cyclo(l-Leu-l-Pro) (5) and 3β,5α,9α-trihydroxy-(22E,24R)-ergosta-7,22-dien-6-one (6), were newly produced by the mutant u2n2h3-3 compared to the parent ZBY-3 strain. Compound 3 was a new compound; 2 was isolated from a natural source for the first time, and all of these compounds were also not yet found in the metabolites of other A. versicolor strains. Compounds 1–6 inhibited the K562 cells, with inhibition rates of 54.6% (1), 72.9% (2), 23.5% (3), 29.6% (4), 30.9% (5) and 51.1% (6) at 100 μg/mL, and inhibited also other human cancer HL-60, BGC-823 and HeLa cells, to some extent. The present study demonstrated the effectiveness of the ultrasound-mediated approach to activate silent metabolite production in fungi by introducing acquired resistance to aminoglycosides and its potential for discovering new compounds from silent fungal metabolic pathways. This approach could be applied to elicit the metabolic potentials of other fungal isolates to discover new compounds from cryptic secondary metabolites.
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Sinnema A, Maat L, van der Gugten AJ, Beyerman HC. Configuration and conformation of all four cocaines from nmr spectra. ACTA ACUST UNITED AC 2010. [DOI: 10.1002/recl.19680870909] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Pfaltz A, Bühler N, Neier R, Hirai K, Eschenmoser A. Photochemische und nicht-photochemische A/D-Secocorrin→Corrin-Cyclisierungen bei 19-Carboxy- und 19-Formyl-1-methyliden-1,19-secocorrinaten. Decarboxylierbarkeit und Deformylierbarkeit von Nickel (II)-19-carboxy- bzw. 19-formyl-corrinaten. Vorläufige Mitt. Helv Chim Acta 2004. [DOI: 10.1002/hlca.19770600817] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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10
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Ding YS, Fowler JS. Highlights of PET studies on chiral radiotracers and drugs at Brookhaven. Drug Dev Res 2003. [DOI: 10.1002/ddr.10221] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Bach T, Brummerhop H. Ungewöhnliche faciale Diastereoselektivität in der Paternò-Büchi-Reaktion eines chiralen Dihydropyrrols – eine kurze Totalsynthese von (+)-Preussin. Angew Chem Int Ed Engl 1998. [DOI: 10.1002/(sici)1521-3757(19981217)110:24<3577::aid-ange3577>3.0.co;2-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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12
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Clive DL, Yeh VS. Formal synthesis of natural epibatidine and of its enantiomer: Use of radical cyclization in an enantiospecific route. Tetrahedron Lett 1998. [DOI: 10.1016/s0040-4039(98)00958-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Pyroglutamate as a Chiral Template for the Synthesis of Alkaloids. ACTA ACUST UNITED AC 1998. [DOI: 10.1016/s0735-8210(98)80006-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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14
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Rigo B, Gautret P, Legrand A, Ghammarti SE, Couturier D. Studies on Pyrrolidinones. An Improved One Pot Synthesis of 1,2,3,5,10,10a-Hexahydrobenz[f]indolizine-3,10-dione. SYNTHETIC COMMUN 1994. [DOI: 10.1080/00397919408010573] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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15
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A short synthesis of C-2 symmetric (2S, 5S) pyrrolidine-2,5 dicarboxylic acid, a constituent of red alga Schizymenia dubyi. Tetrahedron 1993. [DOI: 10.1016/s0040-4020(01)80507-x] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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16
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Melchert RB, Göldlin C, Zweifel U, Welder AA, Boelsterli UA. Differential toxicity of cocaine and its isomers, (+)-cocaine and (-)-psi-cocaine, is associated with stereoselective hydrolysis by hepatic carboxylesterases in cultured rat hepatocytes. Chem Biol Interact 1992; 84:243-58. [PMID: 1423743 DOI: 10.1016/0009-2797(92)90127-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Cocaine induces acute lethal cell injury in rat hepatocytes following N-oxidative metabolic activation by cytochrome P450-dependent and flavin-dependent monooxygenases. Beside this oxidative bioactivation pathway, hepatic carboxylesterases may cleave the carboxymethylester or the benzoylester linkage which leads to molecules found to be non-toxic in vivo. To elucidate the structural requirements of the cocaine molecule for its bioactivation and inactivation, the cytotoxic potential of the natural (-)-cocaine relative to two isomeric forms, (+)-cocaine* (the unnatural enantiomer) and (-)-psi-cocaine (the C2 epimer of the unnatural cocaine) were investigated. Primary short-term cultures of rat hepatocytes obtained from phenobarbital (PB)-pretreated rats were exposed to the drugs for up to 24 h. (-)-Cocaine produced marked time- and concentration-dependent release of lactate dehydrogenase (LDH) into the extracellular medium, whereas the other forms were not cytotoxic (0-1 mM). Furthermore, depletion of cellular glutathione (GSH) with diethylmaleate enhanced LDH release in (-)-cocaine-treated cells and caused marginal cytotoxicity in hepatocytes exposed to the other isomers. To investigate the mechanisms that could be responsible for these isomer-specific effects, the time-dependent metabolic degradation was determined both in cultured hepatocytes and in hepatic microsomes in the presence or absence of the serine carboxylesterase inhibitors, phenylmethylsulfonylfluoride (PMSF) or NaF. All three cocaine analogs were enzymatically degraded, but the rates of ester cleavage greatly varied among the stereoisomers. (-)-Cocaine was primarily N-oxidized via SKF-525A-sensitive pathways, whereas (+)-cocaine was predominantly hydrolyzed by PMSF-sensitive carboxylesterases. In contrast, (-)-psi-cocaine, which is very stable in the absence of cells at 37 degrees C and pH 7.4, was subject to extremely fast enzymatic ester cleavage. In conclusion, these results indicate that the isomer-specific differential cytotoxicity of (-)-cocaine, (+)-cocaine and (-)-psi-cocaine in hepatocytes may be related to stereoselective differences in the rates of hydrolytic inactivation by hepatic carboxylesterases and that the N-oxidative pathway, resulting in hepatocyte injury, may thus be relevant only for (-)-cocaine.
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Affiliation(s)
- R B Melchert
- Institute of Toxicology, ETH, Schwerzenbach, Switzerland
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Cauliez P, Rigo B, Fasseur D, Couturier D. Studies on pyrrolidones. Convenient syntheses of methyl, methylN-methyl- and methylN-methoxymethylpyroglutamate. J Heterocycl Chem 1991. [DOI: 10.1002/jhet.5570280452] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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18
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Gatley SJ. Activities of the enantiomers of cocaine and some related compounds as substrates and inhibitors of plasma butyrylcholinesterase. Biochem Pharmacol 1991; 41:1249-54. [PMID: 2009099 DOI: 10.1016/0006-2952(91)90665-r] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The behaviors of the enantiomers of cocaine (benzoylecgonine methyl ester) and related compounds with butyrylcholinesterase (BChE; EC 3.1.1.8) were investigated spectrophotometrically at 235 nm. The unnatural enantiomer, (+)-cocaine, was hydrolyzed by BChE (extinction coefficient 6.7 L.mmol-1.cm-1) at about half the rate of benzoylcholine, but over 2000 times faster than naturally occurring (-)-cocaine. This rapid hydrolysis of (+)-cocaine may account, in part, for its pharmacological inactivity. (+)-Norcocaine, (+)-benzoylecgonine, (-)-psi-cocaine and tropacocaine were also substrates for BChE. Hydrolysis of (+)-cocaine was sensitive to several standard inhibitors of BChE, including those of competitive, carbamate and organophosphorus classes. Although (-)-cocaine was a poor substrate for debenzoylation, it was a fairly good competitive inhibitor (Ki approximately 10 microM) of the hydrolysis of other substrates. The cocaine metabolites (-)-norcocaine, (-)-benzoylecgonine and (-)-ecgonine methyl ester inhibited BChE with Ki values of 15, 76 and 1300 microM, respectively. (+)-psi-Cocaine had Ki = 3 microM, p-Nitro and p-fluoro derivatives of cocaine and analogs with phenyl and p-fluorophenyl groups in place of the benzoyl ester linkage (WIN 35,065-2 and WIN 35,428) inhibited BChE comparably to (-)-cocaine itself. Both cocaine enantiomers were weak inhibitors of acetylcholinesterase (AChE; EC 3.1.1.7) from human erythrocytes with similar Ki values (160-170 microM). Although it is unlikely that the inhibition of BChE is an important factor in the subjective effects of cocaine, it may have implications for the toxicity of cocaine to the fetus, since BChE appears in the development of the central nervous system before AChE, and has been suggested to function as an embryonic acetylcholinesterase.
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Affiliation(s)
- S J Gatley
- Department of Chemistry, Brookhaven National Laboratory, Upton, NY 11973
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Gatley SJ, MacGregor RR, Fowler JS, Wolf AP, Dewey SL, Schlyer DJ. Rapid stereoselective hydrolysis of (+)-cocaine in baboon plasma prevents its uptake in the brain: implications for behavioral studies. J Neurochem 1990; 54:720-3. [PMID: 2299363 DOI: 10.1111/j.1471-4159.1990.tb01933.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The naturally occurring enantiomer of cocaine, (-)-cocaine, has been previously labeled with 11C on the N-methyl group and used in conjunction with positron emission tomography to show that cocaine is rapidly taken up in the striata of human and baboon brain. In the present study, the behaviorally inactive (+)-cocaine was similarly labeled, with a view to its use for measuring the nonspecific binding of cocaine. No brain uptake was seen, although transport of cocaine into the brain is not expected to be stereoselective. The explanation for the lack of uptake was determined to be very rapid metabolism of (+)-cocaine in the blood. By 30 s after administration of labeled (+)-cocaine, it was undetectable in plasma. In vitro studies demonstrated that (+)-cocaine is 50% debenzoylated to (+)-ecgonine methyl ester within 5 s of exposure to baboon plasma but not to washed erythrocytes. The hydrolysis of (-)-cocaine is at least 1,000 times slower. Serum butyrylcholinesterase (EC 3.1.1.8) appears to be responsible for this hydrolysis, as evidenced by its inhibition by physostigmine and catalysis by commercially available pseudocholinesterase from horse and human blood.
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Affiliation(s)
- S J Gatley
- Department of Chemistry, Brookhaven National Laboratory, Upton, NY 11973
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Ackermann J, Matthes M, Tamm C. Approaches to the Synthesis of Cytochalasans Part9. A versatile concept leading to all structural types of cytochalasans. Helv Chim Acta 1990. [DOI: 10.1002/hlca.19900730113] [Citation(s) in RCA: 61] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Effenberger F, Müller W, Isak H. Aminosäuren, 9 Zur Reaktion von Pyroglutaminsäure-Derivaten mit Phosphorpentachlorid – Darstellung chlorierter Pyrrol-2-carbonsäure-Derivate. ACTA ACUST UNITED AC 1987. [DOI: 10.1002/cber.19871200109] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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24
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Cocaine Hydrochloride. ACTA ACUST UNITED AC 1986. [DOI: 10.1016/s0099-5428(08)60414-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Valensin G, Gaggelli E, Marchettini N, Comparini IB. Conformational and dynamic features of cocaine in DMSO-d6 solution. Biophys Chem 1985; 22:77-81. [PMID: 17007781 DOI: 10.1016/0301-4622(85)80027-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/1984] [Revised: 03/11/1985] [Accepted: 03/14/1985] [Indexed: 11/29/2022]
Abstract
13C spin-lattice relaxation rates, 13C {1H} NOESs, 1H spin-spin relaxation rates and 1H two-dimensional magnetization transfer spectroscopy were used for delineating conformational features of cocaine in DMSO-d6 solution. Two main conformations differing in the orientation of the plane made by the benzoxy substituent with respect to the piperidine ring principal axis were observed. Relatively slow interconversions of the piperidine ring were delineated together with the main motional features of the whole molecule.
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Affiliation(s)
- G Valensin
- Department of Chemistry, University of Siena, Pian dei Mantellini 44 Italy
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Holmstedt B, Fredga A. Sundry episodes in the history of coca and cocaine. JOURNAL OF ETHNOPHARMACOLOGY 1981; 3:113-147. [PMID: 7017286 DOI: 10.1016/0378-8741(81)90050-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
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27
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Emil Hardegger 1913–1978. Adv Carbohydr Chem Biochem 1981. [DOI: 10.1016/s0065-2318(08)60308-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Enders D, Eichenauer H, Pieter R. Enantioselektive Synthese von (-)-(R)-und(+)-(S)-[6]-Gingerol-Gewürzprinzip des Ingwers1). ACTA ACUST UNITED AC 1979. [DOI: 10.1002/cber.19791121118] [Citation(s) in RCA: 63] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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29
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Komiskey HL, Miller DD, LaPidus JB, Patil PN. The isomers of cocaine and tropacocaine: effect on 3H-catecholamine uptake by rat brain synaptosomes. Life Sci 1977; 21:1117-22. [PMID: 916808 DOI: 10.1016/0024-3205(77)90110-2] [Citation(s) in RCA: 39] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Wakabayashi T, Kato Y, Watanabe K. A GENERAL ASYMMETRIC CYCLIZATION. ASYMMETRIC SYNTHETHIS OF OPTICALLY ACTIVE 2-OXO-5-PYRROLIDINEACETIC ACID DERIVATIVES. CHEM LETT 1976. [DOI: 10.1246/cl.1976.1283] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Ebnöther A, Weber HP. [Synthesis and absolute configuration of clemastine and its isomers (author's transl)]. Helv Chim Acta 1976; 59:2462-8. [PMID: 1017970 DOI: 10.1002/hlca.19760590721] [Citation(s) in RCA: 41] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Faber L, Wiegrebe W. [Stereospecific synthesis of two 9,11,12,13, 13a, 14-hexahydrodibenzo(f,h)pyrrolo(1,2-beta)isoquinolines (author's transl)]. Helv Chim Acta 1976; 59:2201-12. [PMID: 1017959 DOI: 10.1002/hlca.19760590633] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Campaigne E, Matthews DP. The reaction ofN-benzylpyroglutamic acid with phenyl grignard. J Heterocycl Chem 1975. [DOI: 10.1002/jhet.5570120238] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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35
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Specification of Asymmetric Nitrogen Atom. Application of the Cahn–Ingold–Prelog Nomenclature to some Tertiary Amines and Quaternary Ammonium Salts. Nature 1961. [DOI: 10.1038/189304a0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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37
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Zeile K, Heusner A. Synthese vonracem. Weinsäuredialdehyd, (±)-Alloteloidinon und (–)-Alloteloidinon. ACTA ACUST UNITED AC 1957. [DOI: 10.1002/cber.19570900926] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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39
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Colloquium der Universität Münster. Angew Chem Int Ed Engl 1956. [DOI: 10.1002/ange.19560680517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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41
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