Palladium/norbornene (Pd/NBE) cooperative catalysis has received enormous attention and found numerous synthetic applications in the past two decades. Considering the critical roles that NBE plays in the catalytic cycle, the use of structurally modified NBEs (smNBEs), starting from 2015, has become an important approach to address limitations and modulate reaction selectivity in Pd/NBE catalysis. This Perspective highlights the development of three types of smNBEs: C1-substituted, C2-substituted, and C5-substituted or C5,C6-disubstituted NBEs, as well as their synthetic applications toward site-selective C-H functionalization. A focus is on the structure-activity relationship of smNBEs in these reactions, and rationales for using smNBEs in many cases have also been provided.

中文翻译：

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结构改性降冰片烯：调节钯/降冰片烯协同催化反应选择性的关键因素

钯/降冰片烯（Pd/NBE）协同催化在过去的二十年中受到了极大的关注，并发现了许多合成应用。考虑到 NBE 在催化循环中的关键作用，从 2015 年开始使用结构改性的 NBE (smNBE) 已成为解决 Pd/NBE 催化中的局限性和调节反应选择性的重要方法。本视角重点介绍了三种类型的 smNBE：C1 取代、C2 取代和 C5 取代或 C5、C6 双取代 NBE 的开发，以及它们在位点选择性 CH 功能化方面的合成应用。重点是在这些反应中 smNBE 的构效关系，并且还提供了在许多情况下使用 smNBE 的基本原理。