The first synthesis of 2′-oxabicyclo[3.1.0]hexylnucleosides, a novel class of bicyclonucleosides, with a north conformation was successfully accomplished starting from (S)-epichlorohydrin via a tandem alkylation–lactonization, a less steric hindrance-dependent silylation in equilibrium and a coupling reaction with nucleobases under Vorbruggen conditions. Addition of acetic acid prevented a benzoyl
2'-氧杂二环[3.1.0]己基核苷,一类新的bicyclonucleosides,第一合成用北构象已成功完成从(起始小号) -表氯醇经由串联烷基化-内酯化,较小的空间位阻依赖性甲硅烷基化在平衡条件下处于平衡状态,并在Vorbruggen条件下与核碱基发生偶联反应。添加乙酸可防止苯甲酰基在与TBAF进行甲硅烷基化过程中迁移。1 H NMR和X射线晶体分析表明,异头作用作用于β-2'-氧杂双环[3.1.0]己基核苷。
Using conformationally locked nucleosides to calibrate the anomeric effect: implications for glycosyl bond stability
作者:Hyung Ryong Moon、Maqbool A. Siddiqui、Guangyu Sun、Igor V. Filippov、Nicholas A. Landsman、Yi-Chien Lee、Kristie M. Adams、Joseph J. Barchi、Jeffrey R. Deschamps、Marc C. Nicklaus、James A. Kelley、Victor E. Marquez
DOI:10.1016/j.tet.2010.06.044
日期:2010.8
and gauche effect play significant roles in steering the North⇆South equilibrium of nucleosides in solution. Two isomeric oxa-bicyclo[3.1.0]hexane nucleosides that are conformationallylocked in either the North or the South conformation of the pseudorotational cycle were designed to study the consequences of having the AE operational or not, independent of other parameters. The rigidity of the system
空间和电子参数,如异头效应 (AE) 和gauche效应在控制溶液中核苷的南北平衡方面起着重要作用。 设计了两个异构的氧杂-双环 [3.1.0] 己烷核苷,它们被构象锁定在假旋转循环的北或南构象中,用于研究 AE 运行与否的后果,独立于其他参数。系统的刚性允许所涉及的轨道的方向设置为“固定”关系,或者是 AE 永久“开启”的反周面,或者是 AE 受损的gauche。这两种替代方案的结果经过高级计算,并通过 X 射线晶体学、糖基键的水解稳定性和 p K a值进行实验测量。