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Closed Access item Stereoselective synthesis of nonsymmetrical difructose dianhydrides from xylylene-tethered d-fructose precursors

Authors:Louis, Farida
García Moreno, María Isabel
Balbuena Olivia, Patricia
Ortiz-Mellet, Carmen
García-Fernández, José Manuel
Issue Date:16-Jan-2008
Citation:Tetrahedron 64(12): 2792-2800 (2008)
Abstract:Nonsymmetrical furanose–pyranose difructose dianhydrides (DFAs), a class of cyclic disaccharides present in foodstuffs, have been prepared in high yield by connecting the reacting monosaccharide moieties through a xylylene bridge prior to triflic acid-promoted bis-spiroketalization. The reaction can then proceed either intra- or intermolecularly, both the regio- and the stereoselectivity being strongly dependent on the spacer length. Noteworthy, the longer m- and p-xylylene positional isomers led to the thermodynamic α-d-fructofuranose β-d-fructopyranose 1,2′:2,1′-dyanhydride 1, the major DFA in commercial caramel, in a stereoselective manner. The shorter o-xylylene tether afforded preferentially the elusive contra-thermodynamic β-d-fructofuranose α-d-fructopyranose diastereomer 2, a trace constituent of caramel. The results have been rationalized in terms of stereoelectronic and conformational properties and offer new perspectives for the preparation of pure DFA standards for analytical and nutritional studies.
Description:9 páginas, 3 figuras, 2 esquemas.
Publisher version (URL):http://dx.doi.org/10.1016/j.tet.2008.01.054
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