Photoinduced Ullmann-type cross-coupling reactions have emerged as a significant advancement in organic synthesis, providing an efficient means to form C–C and C–heteroatom bonds under milder, light-driven conditions. Utilizing copper catalysis, these reactions present considerable benefits over traditional thermal methods by improving reaction efficiency and promoting more sustainable processes. This review evaluates recent mechanistic developments, focusing on the nonchain single-electron transfer (SET) mechanism, which is central to the success of these transformations. The discussion includes an up-to-date overview of both homogeneous and heterogeneous catalytic systems, addressing their practical applications and inherent limitations. In addition, this review identifies key challenges, such as catalyst stability, scalability, and the difficulty of activating less reactive substrates like aryl chlorides. To address these limitations, we propose future research directions aimed at overcoming these obstacles.

中文翻译：

---

光诱导 Ullmann 型交叉偶联反应：机理见解和新出现的挑战


光诱导 Ullmann 型交叉偶联反应已成为有机合成领域的重大进步，提供了一种在较温和的光驱动条件下形成 C-C 和 C-杂原子键的有效方法。利用铜催化，这些反应通过提高反应效率和促进更可持续的过程，与传统热方法相比具有相当大的优势。这篇综述评估了最近的机制发展，重点关注非链单电子转移 （SET） 机制，这是这些转换成功的核心。讨论包括均相和非均相催化系统的最新概述，解决了它们的实际应用和固有局限性。此外，本综述还确定了关键挑战，例如催化剂稳定性、可扩展性以及激活芳基氯化物等反应性较低的底物的难度。为了解决这些限制，我们提出了旨在克服这些障碍的未来研究方向。