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Quantifying electronic effects of common carbohydrate protecting groups in a piperidine model system.
MedLine Citation:
PMID:  21132699     Owner:  NLM     Status:  In-Data-Review    
Abstract/OtherAbstract:
A study of the substituent effects of protecting groups in hydroxypiperidines was carried out and compared with the electronic effects in glycosylation chemistry. 1-Deoxynojirimycin, the aza-sugar analogue of 1-deoxy-D-glucose, was used as a carbohydrate model, and protected with the most common carbohydrate protecting groups. The different stabilization of positive charge on the ring heteroatom was determined by pK(a) measurements. The protecting groups could be ranked in the following way after their destabilization of the piperidinium ion: benzoyl≥acetyl≫4,6-O-benzylidine>benzyl≈methyl>H>3,6-anhydro>tert-butyldimethylsilyl. The observed effects of having protecting groups with different electronic characteristics were found to be in agreement with the "armed-disarmed" concept. Comparison of the pK(a) of benzylated and benzoylated epimers of 3-hydroxy-6-hydroxymethyl piperidines showed increased stabilization of the piperidinium ion in the axial epimer. The difference between axial and equatorial epimers was larger in the benzylated than in the benzoylated piperidines.
Authors:
Mads Heuckendorff; Christian M Pedersen; Mikael Bols
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Chemistry (Weinheim an der Bergstrasse, Germany)     Volume:  16     ISSN:  1521-3765     ISO Abbreviation:  Chemistry     Publication Date:  2010 Dec 
Date Detail:
Created Date:  2010-12-14     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9513783     Medline TA:  Chemistry     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  13982-94     Citation Subset:  IM    
Affiliation:
Department of Chemistry, University of Copenhagen, DK-2100 Copenhagen Ø (Denmark), Fax: (+45) 35-32-02-14.
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