Alkynyl Crown Ethers as a Scaffold for Hyperconjugative Assistance in Noncatalyzed Azide–Alkyne Click Reactions: Ion Sensing through Enhanced Transition-State Stabilization
作者:Brian Gold、Paratchata Batsomboon、Gregory B. Dudley、Igor V. Alabugin
DOI:10.1021/jo500958n
日期:2014.7.3
cycloadditions via selective transition state (TS) stabilization. Optimization of hyperconjugative assistance, provided by the antiperiplanar arrangement of propargylic σ-acceptors relative to the forming bonds, is predicted to relieve strain in cyclooctynes while providing large acceleration to the cycloaddition. The present work investigates this strategy in alkynyl crown ethers, where propargylic
我们最近的工作提供了一种通过选择性过渡态(TS)稳定化来加速叠氮化物/炔烃环加成反应的替代策略。预计由炔丙基σ受体相对于形成键的反平面排列提供的超共轭辅助作用的优化,可以减轻环辛炔的应变,同时为环加成反应提供较大的加速度。本工作在炔基冠醚中研究了该策略,其中大环内的炔丙基C-O键被约束在接近超结合辅助的适当排列附近。将σ受体预组织为超共轭相互作用的最佳安排可能会减轻一部分熵的损失,从而达到TS。可以加强最佳对齐,