Document Detail

Squaric acid N-hydroxylamides: synthesis, structure, and properties of vinylogous hydroxamic acid analogues.
MedLine Citation:
PMID:  14629141     Owner:  NLM     Status:  MEDLINE    
The synthesis of squaric acid N-hydroxylamide esters 5 and amides 6 from dimethyl squarate 2a is described. These derivatives are analogues of the naturally occurring iron(III) chelator hydroxamic acid. On the basis of a comparative reactivity study, a concerted retro-Cope mechanism for the formation of the N-hydroxylamide esters 5 by reaction of dimethyl squarate with hydroxylamines is proposed. A preliminary iron(III) binding study of these hydroxamic acid analogues is presented, demonstrating binding of iron(III) to amides 6 in aqueous solutions, while the esters 5 did not show any sign of metal ion binding. 13C NMR spectroscopic data (chemical shift and spin-lattice relaxation time determination) of these and related derivatives delineate the resonance structures predominant in these molecules. The resonance structures of the derivatives rationalize their spectroscopic data, chemical reactivity, and iron(III) binding properties. Single-crystal X-ray structure analyses of squaric acid N-hydroxylamide ester 5b and squaric acid N-hydroxylamide amide 6c confirm their connectivity and provide structural evidence supporting the spectroscopically derived conclusions. The squaric acid N-hydroxylamides are potentially useful in the construction of chemosensors for iron(III).
Nathaniel C Lim; Martha D Morton; Hilary A Jenkins; Christian Brückner
Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of organic chemistry     Volume:  68     ISSN:  0022-3263     ISO Abbreviation:  J. Org. Chem.     Publication Date:  2003 Nov 
Date Detail:
Created Date:  2003-11-21     Completed Date:  2004-03-24     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  2985193R     Medline TA:  J Org Chem     Country:  United States    
Other Details:
Languages:  eng     Pagination:  9233-41     Citation Subset:  IM    
Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269-3060, USA.
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MeSH Terms
Binding, Competitive
Crystallography, X-Ray
Cyclobutanes / chemical synthesis*,  chemistry
Ferric Compounds / analysis,  chemistry
Hydroxamic Acids / chemical synthesis*,  chemistry
Hydroxylamines / chemistry*
Magnetic Resonance Spectroscopy
Models, Chemical
Models, Molecular
Molecular Structure
Structure-Activity Relationship
Vinyl Compounds / chemical synthesis*,  chemistry
Reg. No./Substance:
0/Cyclobutanes; 0/Ferric Compounds; 0/Hydroxamic Acids; 0/Hydroxylamines; 0/Vinyl Compounds; 2892-51-5/squaric acid

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