The role of nucleophilic catalysis in chemistry and stereochemistry of ribonucleosideH-phosphonate condensation
作者:Michal Sobkowski、Jacek Stawinski、Adam Kraszewski
DOI:10.1039/b812780h
日期:——
The efficiency and stereoselectivity of condensation of ribonucleoside 3′-H-phosphonates with alcohols were investigated as a function of amines used for the reaction. It was found that irrespective of the presence or absence of nucleophilic catalysts, the Dynamic Kinetic Asymmetric Transformation (DYKAT) was the major factor responsible for the stereoselective formation of the DP(SP) isomers of the H-phosphonate diesters, and a mechanistic rationalization of this observation was proposed. In addition, studies on the reactions carried out in the presence of various bases led to the conclusion that certain sterically hindered pyridines, e.g.2,6-lutidine, may act as nucleophilic catalysts in the condensation of ribonucleoside 3′-H-phosphonates with alcohols.
研究了核糖核苷3′-H-磷酸酯与醇的缩合反应的效率和立体选择性,作为反应中使用的胺的函数。结果发现,无论是否存在亲核催化剂,动态动力学不对称转化(DYKAT)是导致H-磷酸二酯DP(SP)异构体立体选择性形成的主要因素,并提出了对此观察结果的机制解释。此外,对在各种碱存在下进行的反应的研究得出结论,某些空间位阻较大的吡啶类化合物,例如2,6-路丁啶,可能在核糖核苷3′-H-磷酸酯与醇的缩合反应中起到亲核催化剂的作用。