The impact of oxacarbenium ion conformers on the stereochemical outcome of glycosylations
作者:Marthe T.C. Walvoort、Jasper Dinkelaar、Leendert J. van den Bos、Gerrit Lodder、Herman S. Overkleeft、Jeroen D.C. Codée、Gijsbert A. van der Marel
DOI:10.1016/j.carres.2010.02.027
日期:2010.7
The search for stereoselective glycosylation reactions has occupied synthetic carbohydrate chemists for decades. Traditionally, most attention has been focused on controlling the S(N)2-like substitution of anomeric leaving groups as highlighted by Lemieux's in situ anomerization protocol and by the discovery of anomeric triflates as reactive intermediates in the stereoselective formation of beta-mannosides
立体选择性糖基化反应的研究已经占据了合成碳水化合物化学家的数十年。传统上,大多数注意力都集中在控制异头离去基团的S(N)2取代上,如Lemieux的原位异构化方案和发现异头三氟甲磺酸酯作为β-甘露糖苷立体选择性形成中的反应性中间体所强调的那样。近来,已经清楚的是,类似S(N)1的反应途径也可以导致高度选择性的糖基化反应。这篇综述描述了立体选择性糖基化的一些最新实例,其中氧杂碳鎓离子被认为是选择性的基础。