Epimerisation of Carbohydrates and Cyclitols, 17.1 Synthesis of Glycosyl Azides and N-Acetyl Glycosyl Amines of Rare Monosaccharides
作者:Christian Hager、Ralf Miethchen、Helmut Reinke
DOI:10.1055/s-2000-6250
日期:——
The glycosyl azides 1 (d-arabino), 3 (l-fuco), 5 (d-manno), and 7 (d-galacto) were epimerised in a one-pot procedure by heating with chloral/DCC/1,2-dichloroethane in good yields. The respective products, epimerised at the C-3 atom, have d-lyxo (2), l-gulo (4), d-altro (6), and d-gulo (8, 9) configuration. Compound 8, directly generated or obtained by deformylation of its 6-O-formyl derivative 9, was used as the key intermediate for further syntheses. Besides the acetylation of 8 to 10, and decarbamoylation to the 4,6-dihydroxy derivative 11, the latter 11 was acetylated to 12 and benzylated to 13. Moreover, the azide function of 8 was converted into an amino group using tributyltin hydride/AIBN or Staudinger conditions. The amino derivatives were isolated in the form of their N-acetyl derivatives 14 and 15, respectively. Finally, the dichloroethylidene (14) and the trichloroethylidene (15) groups were hydrodechlorinated forming the same ethylidene derivative 16. Crystal structures are given for the gulopyranoses 4 and 12.
糖苷叠氮化物1(d-阿拉伯糖)、3(l-藤糖)、5(d-甘露糖)和7(d-半乳糖)通过与氯醛/DCC/1,2-二氯乙烷加热反应,在一步法中进行了表异构化,反应产率良好。相应的产物在C-3位发生了表异构化,分别具有d-氨基(2)、l-古洛(4)、d-阿尔特罗(6)和d-古洛(8、9)构型。化合物8是直接生成的或通过其6-O-甲酰衍生物9去甲酰化获得的,作为进一步合成的关键中间体。除了将8乙酰化生成10和去氨基化生成4,6-二羟基衍生物11外,后者11又乙酰化为12并苄基化为13。此外,8的叠氮功能团被转化为氨基,使用了三丁基锡氢化物/AIBN或斯陶丁格条件。氨基衍生物以其N-乙酰衍生物14和15的形式被分离。最后,二氯乙烯基(14)和三氯乙烯基(15)基团被去除氯化形成相同的乙烯基衍生物16。提供了古洛吡喃糖4和12的晶体结构。