Source:http://linkedlifedata.com/resource/pubmed/id/19275130
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| Predicate | Object |
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| rdf:type | |
| lifeskim:mentions | |
| pubmed:issue |
7
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| pubmed:dateCreated |
2009-3-27
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| pubmed:abstractText |
The present study was undertaken to shed light on the mechanism of the epimerization of cis-1,2,3-trisubstituted tetrahydro-beta-carbolines into the trans isomers via a potential carbocationic intermediate at C(1). In order to study the pathway involved in C(1)-N(2) bond cleavage, the electronic character of the carbon atom at C-1 was altered by substitution of electron-rich and electron-poor phenyl rings at this position. This provided direct evidence of the effects of charge at the proposed site of the carbocationic intermediate. In this regard, a diverse set of 1-(phenyl substituted)-2-benzyl-3-ethoxycarbonyl-1,2,3,4-tetrahydro-beta-carbolines has been synthesized via the Pictet-Spengler reaction by condensation of l-tryptophan derivatives with electron-poor and electron-rich aromatic aldehydes. The epimers involved in the isomerization mechanism were investigated by dynamic (1)H and (13)C NMR spectroscopic and X-ray crystallographic analyses. The kinetic studies, which involved conversion of cis diastereomers into their trans counterparts, were carried out in dilute TFA/CH(2)Cl(2). The 1-(4-methoxyphenyl) cis diastereomer epimerized at a much faster rate into the corresponding trans diastereomer than the related 1-(4-nitrophenyl) cis diastereomer epimerized. These observations provide support for the carbocationic intermediate in the C(1)-N(2) scission process. The understanding of this epimerization process is of importance when Pictet-Spengler reactions are carried out under acidic conditions during the synthesis of indole alkaloids.
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| pubmed:grant | |
| pubmed:commentsCorrections |
http://linkedlifedata.com/resource/pubmed/commentcorrection/19275130-10814213,
http://linkedlifedata.com/resource/pubmed/commentcorrection/19275130-10891229,
http://linkedlifedata.com/resource/pubmed/commentcorrection/19275130-11978852,
http://linkedlifedata.com/resource/pubmed/commentcorrection/19275130-12323013,
http://linkedlifedata.com/resource/pubmed/commentcorrection/19275130-12868917,
http://linkedlifedata.com/resource/pubmed/commentcorrection/19275130-14666116,
http://linkedlifedata.com/resource/pubmed/commentcorrection/19275130-14759191,
http://linkedlifedata.com/resource/pubmed/commentcorrection/19275130-15153007,
http://linkedlifedata.com/resource/pubmed/commentcorrection/19275130-15244409,
http://linkedlifedata.com/resource/pubmed/commentcorrection/19275130-15327311,
http://linkedlifedata.com/resource/pubmed/commentcorrection/19275130-16048327,
http://linkedlifedata.com/resource/pubmed/commentcorrection/19275130-16433519,
http://linkedlifedata.com/resource/pubmed/commentcorrection/19275130-17081019,
http://linkedlifedata.com/resource/pubmed/commentcorrection/19275130-17253853,
http://linkedlifedata.com/resource/pubmed/commentcorrection/19275130-17685530,
http://linkedlifedata.com/resource/pubmed/commentcorrection/19275130-17702087,
http://linkedlifedata.com/resource/pubmed/commentcorrection/19275130-18479086,
http://linkedlifedata.com/resource/pubmed/commentcorrection/19275130-18616320,
http://linkedlifedata.com/resource/pubmed/commentcorrection/19275130-6065625
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| pubmed:language |
eng
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| pubmed:journal | |
| pubmed:citationSubset |
IM
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| pubmed:chemical | |
| pubmed:status |
MEDLINE
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| pubmed:month |
Apr
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| pubmed:issn |
1520-6904
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| pubmed:author | |
| pubmed:issnType |
Electronic
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| pubmed:day |
3
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| pubmed:volume |
74
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| pubmed:owner |
NLM
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| pubmed:authorsComplete |
Y
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| pubmed:pagination |
2771-9
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| pubmed:dateRevised |
2011-9-26
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| pubmed:meshHeading | |
| pubmed:year |
2009
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| pubmed:articleTitle |
Study of the cis to trans isomerization of 1-phenyl-2,3-disubstituted tetrahydro-beta-carbolines at C(1). Evidence for the carbocation-mediated mechanism.
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| pubmed:affiliation |
Department of Chemistry, University of Wisconsin-Whitewater, Whitewater, Wisconsin 53190, USA.
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| pubmed:publicationType |
Journal Article,
Research Support, Non-U.S. Gov't,
Research Support, N.I.H., Extramural
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