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 conformationally locked 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。