The N-7 regioisomer of 2-chloro-2′-deoxyadenosine: synthesis, crystal structure, conformation, and stability
作者:Victoria L. Worthington、William Fraser、Carl H. Schwalbe
DOI:10.1016/0008-6215(95)00168-s
日期:1995.10
from the crystal structure of 7 suggest that the molecule can adopt either anti or syn conformations with a slight preference for anti by 0.4 kcal mol − in heat of formation ( ΔH f ). NOE experiments in (CD 3 ) 2 SO solution support the theoretical results indicating the presence of both syn and anti conformations and that the anti population is marginally favoured. The antileukaemic agent 2-chloro-2′-deoxyadenosine
摘要核苷6-氨基-2-氯-7-(2-脱氧-β-d-赤型呋喃呋喃糖基)-7H-嘌呤7可从2,6-二氯嘌呤分两步获得。这种不寻常的核苷的晶体结构显示了一个分叉的分子内氢键,从氨基到O-5',而到O-4'的分支较弱,这施加了同糖苷扭转角:X = 67.0°。使用AM1参数的半经验计算和从7的晶体结构得出的原子坐标的优化表明该分子可以采用反式或顺式构象,在形成热中(ΔHf )。(CD 3)2 SO溶液中的NOE实验支持理论结果,该理论结果表明同时存在顺式构象和反式构象,并且抗人口数受到偏爱。N-7区域异构体7的抗白血病药物2-氯-2'-脱氧腺苷(6)的稳定性为9.6 kcal mol-,比7更稳定。6比7更高的稳定性似乎主要归因于糖苷配基互变异构体8和9的相对稳定性,二者之间的能量差为6.7 kcal mol-,而9 H互变异构体8更好。同样,除去2-氯取代基对互变异构影响很小。