Total Facial Discrimination of 1,3-Dipolar Cycloadditions in a <scp>d</scp>-Erythrose 1,3-Dioxane Template: Computational Studies of a Concerted Mechanism
作者:Cristina E. A. Sousa、António M. P. Ribeiro、António Gil Fortes、Nuno M. F. S. A. Cerqueira、Maria J. Alves
DOI:10.1021/acs.joc.6b02518
日期:2017.1.20
the regioselectivity is complete with alkyl azides and phenyldiazomethane, but is inexistence with nitrile oxides. Computational studies were performed to understand the mechanisms of cycloadditions. All the studied cycloadditions were found to be concerted involving small free activation energies and are all exoenergonic. The stereoselectivity is due to a combined result of the steric effect H-8a
从d合成了新的d-赤藓糖1,3-二恶烷衍生物-葡萄糖,被发现是一种高度立体选择性的模板,如双极性亲和剂。根据其性质,使用了不同的烯丙基型1,3-偶极子,因此具有不同的区域选择性。烷基叠氮化物和苯基重氮甲烷的区域选择性是完全的,而腈氧化物则不存在。进行了计算研究以了解环加成的机理。发现所有研究的环加成物都涉及小的自由活化能,并且都是外能的。立体选择性是由于空间效应H-8a和* C–O对传入的1,3-偶极子的超共轭效应的综合结果所致。在烷基叠氮化物和苯基重氮甲烷中观察到的区域选择性主要取决于环加成过程中的畸变效应。