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Closed Access item Intramolecular 1,8-hydrogen-atom transfer reactions in (1-->4)-O-disaccharide systems: conformational and stereochemical requirements

Authors:Francisco, Cosme G.
Herrera, Antonio J.
Kennedy, Alan R.
Martín, Ángeles
Melián, Daniel
Pérez-Martín, Inés
Quintanal, Luis M.
Suárez, Ernesto
Keywords:Carbohydrates, Disaccharides, Esters, Radical reactions, Trioxocane
Issue Date:1-Oct-2008
Publisher:John Wiley & Sons
Citation:Chemistry - A European Journal 14(33): 10369-10381 (2008)
Abstract:The stereochemical and conformational factors controlling the intramolecular hydrogen-atom transfer (HAT) reaction between the two pyranose units in a (1-->4)-O-disaccharide when promoted by a primary 6-O-yl radical are studied. Models with α-D-Glcp-(1-->4)-β-D-Glcp, α-L-Rhamp-(1-->4)-α-D-Galp or α-D-Manp-(1-->4)-β-L-Gulp skeletons led exclusively to the abstraction of the hydrogen from H--C-5' and the formation, through a nine-membered transition state, of a 1,3,5-trioxocane ring system in a stable boat-chair conformation. Notwithstanding, derivatives of α-L-Rhamp-(1-->4)-α-D-Glcp or α-D-Manp-(1-->4)-α-D-Galp exclusively abstract the hydrogen from H--C-1' through a seven-membered transition state and, therefore, lead to an interglycosidic spiro ortho ester.
Description:13 pages, 1 figure, 1 table, 7 schemes.-- PMID: 18830990 [PubMed].
Supporting information (30 pages) available at: http://www3.interscience.wiley.com/journal/121427980/suppinfo
Publisher version (URL):http://dx.doi.org/10.1002/chem.200801414
Appears in Collections:(IPNA) Artículos

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