N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky Prospekt, 119991 Moscow, Russia.
Molecules. 2023 Jan 17;28(3):934. doi: 10.3390/molecules28030934.
Despite the obvious advantages of heterogeneous photocatalysts (availability, stability, recyclability, the ease of separation from products and safety) their application in organic synthesis faces serious challenges: generally low efficiency and selectivity compared to homogeneous photocatalytic systems. The development of strategies for improving the catalytic properties of semiconductor materials is the key to their introduction into organic synthesis. In the present work, a hybrid photocatalytic system involving both heterogeneous catalyst (TiO) and homogeneous organocatalyst (-hydroxyphthalimide, NHPI) was proposed for the cross-dehydrogenative C-C coupling of electron-deficient -heterocycles with ethers employing -BuOOH as the terminal oxidant. It should be noted that each of the catalysts is completely ineffective when used separately under visible light in this transformation. The occurrence of visible light absorption upon the interaction of NHPI with the TiO surface and the generation of reactive phthalimide--oxyl (PINO) radicals upon irradiation with visible light are considered to be the main factors determining the high catalytic efficiency. The proposed method is suitable for the coupling of π-deficient pyridine, quinoline, pyrazine, and quinoxaline heteroarenes with various non-activated ethers.
尽管异相光催化剂（易得、稳定、可回收、易于与产物分离且安全）具有明显的优势，但它们在有机合成中的应用仍面临严峻挑战：与均相光催化体系相比，其效率和选择性通常较低。开发提高半导体材料催化性能的策略是将其引入有机合成的关键。在本工作中，提出了一种涉及异相催化剂（TiO）和均相有机催化剂（-羟基邻苯二甲酰亚胺，NHPI）的杂化光催化体系，用于在叔丁基过氧作为末端氧化剂的条件下，通过缺电子 -杂环与醚的交叉脱氢 C-C 偶联。值得注意的是，在可见光照射下，每种催化剂在该转化中单独使用时均完全无效。NHPI 与 TiO 表面相互作用时发生可见光吸收，以及可见光照射时生成反应性邻苯二甲酰亚胺-氧自由基（PINO 自由基）被认为是决定高催化效率的主要因素。所提出的方法适用于各种非活性醚与缺π吡啶、喹啉、吡嗪和喹喔啉杂芳环的偶联。
