| Unexpected synthesis of conformationally restricted analogues of gamma-amino butyric acid (GABA): mechanism elucidation by electrospray ionization mass spectrometry. | |
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MedLine Citation:
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PMID: 15624912 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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From previous results with lower homologues, dehydroiodination of the three alkenyl-beta-enamino esters 3a-c was expected to provide six-membered N-heterocyclic products. The reactions of 3a-c with triethylamine are found to lead, however, to the unexpected stereoselective synthesis of the trisubstituted cyclopentane derivatives 4a-c, as confirmed by IR and NMR spectroscopy. Cyclopentanes 4a-c bear two chiral centers and a gamma-amino ester moiety, and are therefore conformationally restricted analogues of gamma-amino butyric acid (GABA), which is the major inhibitory neurotransmitter in the central nervous system. Use of electrospray ionization mass (ESI-MS) and tandem mass spectrometry (ESI-MS/MS) allowed the key iminium ion intermediates 5a-c(+), as well as the protonated molecules of both the reactant and final products, [3a-c + H](+) and [4a-c + H](+), to be intercepted and structurally characterized. From these findings a mechanism for this unexpected but synthetically attractive and efficient stereoselective reaction is proposed. |
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Authors:
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Helena M C Ferraz; Fernando L C Pereira; Erika R S Gonçalo; Leonardo S Santos; Marcos N Eberlin |
Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: The Journal of organic chemistry Volume: 70 ISSN: 0022-3263 ISO Abbreviation: J. Org. Chem. Publication Date: 2005 Jan |
Date Detail:
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Created Date: 2004-12-30 Completed Date: 2005-02-23 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 2985193R Medline TA: J Org Chem Country: United States |
Other Details:
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Languages: eng Pagination: 110-4 Citation Subset: IM |
Affiliation:
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Institute of Chemistry, University of São Paulo-USP, São Paulo SP, 05508-900, Brazil. hmferraz@iq.usp.br |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Combinatorial Chemistry Techniques Cyclopentanes / chemical synthesis* Molecular Structure Spectrometry, Mass, Electrospray Ionization / methods* Stereoisomerism gamma-Aminobutyric Acid / analogs & derivatives*, chemical synthesis*, chemistry |
| Chemical | |
Reg. No./Substance:
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0/Cyclopentanes; 56-12-2/gamma-Aminobutyric Acid |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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