A novel electron donor–acceptor (EDA) complex catalysis strategy has been developed, employing N,N′-bis[3,5-bis(trifluoromethyl)phenyl]thiourea as a pre-catalyst and a base as a pre-catalyst initiation switch to generate iminyl radical intermediates from oxime esters via a single-electron reduction process under blue LED irradiation. This approach not only in situ converts a cost-effective and stable precursor into an electron donor for the catalytic system but also achieves the regeneration of the donor species. By utilizing 2–5 mol% of thiourea, a wide range of nitrogen-containing compounds, including pyrrolines, ketonitriles, phenanthridines, pyridines, and quinolines, were successfully synthesized, emphasizing the versatility of this approach. The pivotal roles of the pre-catalyst, base, and blue LED irradiation were verified through control experiments. Mechanistic studies and density functional theory calculations indicate that the generated thiouronyl anions serve as catalytic electron-donor species under blue light irradiation, enabling the single-electron reduction of oxime esters to form iminyl radical intermediates.

中文翻译：

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硫脲作为肟酯电子供体-受体复合物光活化平台的预催化剂

开发了一种新型电子供体-受体（EDA）复合物催化策略，采用N , N '-双[3,5-双（三氟甲基）苯基]硫脲作为预催化剂，碱作为预催化剂引发开关在蓝色 LED 照射下通过单电子还原过程从肟酯生成亚氨基自由基中间体。这种方法不仅将具有成本效益且稳定的前体原位转化为催化系统的电子供体，而且还实现了供体物质的再生。通过利用2-5 mol%的硫脲，成功合成了多种含氮化合物，包括吡咯啉、酮腈、菲啶、吡啶和喹啉，强调了该方法的多功能性。通过对照实验验证了预催化剂、基础和蓝色 LED 照射的关键作用。机理研究和密度泛函理论计算表明，生成的硫脲酰阴离子在蓝光照射下作为催化电子供体物种，使得肟酯的单电子还原形成亚氨基自由基中间体。