Document Detail

Conformational response of tartaric acid to derivatization: role of 1,3-dipole-dipole interactions.
MedLine Citation:
PMID:  15991225     Owner:  NLM     Status:  PubMed-not-MEDLINE    
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.
Jacek Gawronski; Anna Długokinska; Jakub Grajewski; Agnieszka Plutecka; Urszula Rychlewska
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Chirality     Volume:  17     ISSN:  0899-0042     ISO Abbreviation:  Chirality     Publication Date:  2005 Aug 
Date Detail:
Created Date:  2005-07-06     Completed Date:  2005-09-16     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8914261     Medline TA:  Chirality     Country:  United States    
Other Details:
Languages:  eng     Pagination:  388-95     Citation Subset:  -    
Department of Chemistry, A. Mickiewicz University, Poznan, Poland.
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