The importance of fluorinated products in pharmaceutical and medicinal chemistry has necessitated the development of synthetic fluorination methods, of which direct C–H fluorination is among the most powerful. Despite the challenges and limitations associated with the direct fluorination of unactivated C–H bonds, appreciable advancements in manipulating the selectivity and reactivity have been made, especially via transition metal catalysis and photochemistry. Where transition metal catalysis provides one strategy for C–H bond activation, transition-metal-free photochemical C–H fluorination can provide a complementary selectivity via a radical mechanism that proceeds under milder conditions than thermal radical activation methods. One exciting development in C–F bond formation is the use of small-molecule photosensitizers, allowing the reactions i) to proceed under mild conditions, ii) to be user-friendly, iii) to be cost-effective and iv) to be more amenable to scalability than typical photoredox-catalyzed methods. In this review, we highlight photosensitized C–H fluorination as a recent strategy for the direct and remote activation of C–H (especially C(sp³)–H) bonds. To guide the readers, we present the developing mechanistic understandings of these reactions and exemplify concepts to assist the future planning of reactions.

中文翻译：

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有机合成中的光敏直接CH氟化和三氟甲基化。


氟化产品在制药和药物化学中的重要性使得合成氟化方法的开发成为必要，其中直接 C-H 氟化是最强大的方法之一。尽管未活化的 C-H 键的直接氟化存在挑战和限制，但在控制选择性和反应性方面已经取得了显着的进步，特别是通过过渡金属催化和光化学。过渡金属催化为 C-H 键活化提供了一种策略，而无过渡金属的光化学 C-H 氟化可以通过自由基机制提供补充选择性，该自由基机制在比热自由基活化方法更温和的条件下进行。 C-F 键形成方面的一项令人兴奋的进展是使用小分子光敏剂，使反应 i) 在温和条件下进行，ii) 用户友好，iii) 具有成本效益，iv) 更高效比典型的光氧化还原催化方法更易于扩展。在这篇综述中，我们重点介绍光敏 C-H 氟化作为直接和远程激活 C-H（尤其是 C(sp ³ )-H）键的最新策略。为了指导读者，我们提出了对这些反应不断发展的机械理解，并举例说明了概念以协助未来的反应规划。