Mono-Glycosylated 3-N-Alkylcatechols: Direct Synthesis from Glycosylacetates, 1H Nmr Analysis and Conformational Studies |
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Authors: | Stéphane Mabic Jean-Pierre Lepoittevin |
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Institution: | Laboratoire de Dermatochimie associé au CNRS, Université Louis Pasteur, Clinique Dermatologique , CHU, F-67091, Strasbourg, France |
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Abstract: | ABSTRACT The direct coupling of 3-n-alkyl catechols to the acetate or trichloroacetimidate derivatives of β-D- or α-D-glycosides (glucose, galactose, xylose, mannose and maltose) catalyzed by BF3Ot2 has been studied. β-Glycosides with an equatorial acetate group at position 2 formed exclusively β adducts with yields of 60–80%. α-Glycosides with an equatorial acetate group at position 2 formed β adducts, while β-glycosides with an axial acetate group formed α adducts when activated as trichloroacetimidates, with yields of 70–85%. This was applied to the coupling of 3-n-alkylcatechols of increasing chain length (up to C15) to sugar derivatives. The coupling position of glycosides on the catechol was determined either by differential NOE experiments and by the regioselective synthesis of 1-(O-β-D-glucopyranosyl)-3-pentadecylcatechol, a water soluble analogue of the poison ivy skin allergen. 1H NMR of acetylated and deprotected compounds were investigated and the conformational preferences of the C6 side chain determined using molecular modeling. |
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