o-Xylylene Protecting Group in Carbohydrate Chemistry: Application to the Regioselective Protection of a Single vic-Diol Segment in Cyclodextrins
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- 作者：Patricia Balbuena ; Rita Gon莽alves-Pereira ; Jos茅 L. Jim茅nez Blanco ; M. Isabel Garc铆a-Moreno ; David Lesur ; Carmen Ortiz Mellet ; Jos茅 M. Garc铆a Fern谩ndez
- 刊名：The Journal of Organic Chemistry
- 出版年：2013
- 出版时间：February 15, 2013
- 年：2013
- 卷：78
- 期：4
- 页码：1390-1403
- 全文大小：613K
- 年卷期：v.78,no.4(February 15, 2013)
- ISSN：1520-6904
文摘
A systematic study of the suitability of 伪,伪鈥?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; 伪, 尾, and 纬CD).