| Conformational response of tartaric acid to derivatization: role of 1,3-dipole-dipole interactions. | |
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MedLine Citation:
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PMID: 15991225 Owner: NLM Status: PubMed-not-MEDLINE |
Abstract/OtherAbstract:
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The four-carbon chain in (R,R)-tartaric acid derivatives is predominantly antiperiplanar (trans) in the acid, its salts, esters, and NH-amides, while (-)-synclinal (gauche) conformer is the most abundant in N,N'-tetraalkyltartramides. Trialkylsilylation or tert-butylation of the hydroxy groups at C2 and C3 does not appear to affect the conformational preference of NH-tartramides, but it does change the conformational equilibrium in the case of tartrates (toward (-)-gauche) and N,N'-tetraalkyltartramides (toward trans), as judged from the NMR data. X-ray diffraction data point to the stabilizing role of antiparallel dipole-dipole interactions due to the 1,3-CO/CH bonds. These interactions can be found in the trans and (-)-gauche conformers but are not possible for the (+)-gauche conformers of (R,R)-tartaric acid derivatives. This rationalizes small proportion of (+)-gauche conformers in tartaric acid derivatives and points to a significance of 1,3-dipole-dipole interactions. The conformation around the C1-C2 (and C3-C4) bond is different in tartrates (O-C-C=O, syn) and tartramides (O-C-C=O, anti); the CD data (n-pi* band) show that O-silylation or O-tert-butylation brings about conformational changes around the C1-C2 bond in the case of N,N'-tetraalkyldiamides only. |
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Authors:
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Jacek Gawronski; Anna Długokinska; Jakub Grajewski; Agnieszka Plutecka; Urszula Rychlewska |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Chirality Volume: 17 ISSN: 0899-0042 ISO Abbreviation: Chirality Publication Date: 2005 Aug |
Date Detail:
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Created Date: 2005-07-06 Completed Date: 2005-09-16 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 8914261 Medline TA: Chirality Country: United States |
Other Details:
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Languages: eng Pagination: 388-95 Citation Subset: - |
Affiliation:
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Department of Chemistry, A. Mickiewicz University, Poznan, Poland. gawronsk@amu.edu.pl |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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