Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India.
Chemistry. 2018 Dec 5;24(68):17906-17910. doi: 10.1002/chem.201804351. Epub 2018 Nov 2.
Achieving site-selective C-H functionalization of arene is a fundamental challenge, as it is mainly controlled by the electronic nature of the molecules. A chelation-assisted C-H functionalization strategy overcomes the selectivity issues by utilizing distance and geometry of covalently attached directing groups (DGs). This strategy requires stoichiometric DG installation/removal and a suitable functional group on which to tether the DG. Such strategies are ineffective for small heterocycles unless suitable functional groups are added. Moreover, heterocycles are not the judicious choice as substrates owing to the possibilities of catalyst deactivation. Inspired by recent developments, this work demonstrates the utilization of a chelating template backbone bearing covalently attached directing groups, which enables site-selective remote C-H functionalization of heterocycles. The observed selectivity is the outcome of non-covalent interactions between the heterocycles and bifunctional template backbone.
实现芳环的位点选择性 C-H 功能化是一个基本的挑战，因为它主要受分子的电子性质控制。通过利用共价连接的导向基团 (DG) 的距离和几何形状，螯合辅助的 C-H 功能化策略克服了选择性问题。该策略需要化学计量的 DG 安装/去除以及用于系链 DG 的合适官能团。对于小杂环，除非添加合适的官能团，否则这些策略无效。此外，由于催化剂失活的可能性，杂环不是明智的底物选择。受最近的发展启发，本工作展示了利用带有共价连接导向基团的螯合模板骨架，实现杂环的远程位点选择性 C-H 功能化。观察到的选择性是杂环与双功能模板骨架之间非共价相互作用的结果。
