title: o-Xylylene protecting group in carbohydrate chemistry: application to the regioselective protection of a single vic-diol segment in cyclodextrins.
abstract: A systematic study of the suitability of α,α'-dibromo-o-xylene as a reagent for cyclic o-xylylene protection of vic-diols in different monosaccharide substrates is reported. The installation of this protecting group, formally equivalent to a di-O-benzylation reaction, proceeds with good regioselectivity toward 1,2-trans-diequatorial diol systems in pyranose and furanose rings. Initially, the benzyl ether-type derivative of the more acidic hydroxyl is preferentially formed. Subsequent intramolecular etherification toward the equatorial-oriented vicinal OH is kinetically favored. The methodology has been implemented for the simultaneous protection of the secondary O-2 and O-3 positions of a single d-glucopyranosyl unit in cyclic oligosaccharides of the cyclodextrin (CD) family (cyclomaltohexa-, -hepta-, and -octaose; α, β, and γCD).
authors: Instituto de Investigaciones Químicas, CSIC-Universidad de Sevilla, c/Américo Vespucio 49, Isla de la Cartuja, E-41092 Sevilla, Spain.
authors: Patricia
authors: P
authors: Balbuena
authors: Rita
authors: R
authors: Gonçalves-Pereira
authors: José L
authors: JL
authors: Jiménez Blanco
authors: M Isabel
authors: MI
authors: García-Moreno
authors: David
authors: D
authors: Lesur
authors: Carmen
authors: C
authors: Ortiz Mellet
authors: José M
authors: JM
authors: García Fernández