Filipović Ana, Džambaski Zdravko, Bondžić Aleksandra M, Bondžić Bojan P
Institute of Chemistry, Technology and Metallurgy, University of Belgrade, National Institute of the Republic of Serbia, Njegoševa 12, 11000, Belgrade, Republic of Serbia.
Vinča Institute of Nuclear Sciences, National Institute of the Republic of Serbia, University of Belgrade, P.O. Box 522, 11000, Belgrade, Serbia.
Photochem Photobiol Sci. 2023 Oct;22(10):2259-2270. doi: 10.1007/s43630-023-00448-8. Epub 2023 Jun 21.
Visible light promoted photoredox catalyzed formation of α-amino radicals from cyclic tertiary amine compounds and their subsequent addition to Michael acceptors performed in flow conditions allowed access to a wide range of functionalized N-aryl-substituted tetrahydroisoquinolines (THIQs) and N-aryl-substituted tetrahydro-β-carbolines (THBCs). Visible light in conjunction with Ru(bpy)Cl photocatalyst allowed the formation and high reactivities of α-amino radicals in flow conditions at room temperature. These reactions gave valuable products with high efficiencies; some previously unavailable reaction pathways photo or thermal reaction conditions; i.e. direct synthesis of 1-substituted (THBCs) via α-amino radical path were successfully realized in flow. The use of custom-made FEP tube microreactor proved to be the key to succesfull α-amino-radical formation and overall reaction performance in flow. Three types of light transparent custom-made microfluidic devices were tested, among them glass/silicon and FEP type reactor showed very good results in the conversion of tested compounds. Plausible reaction mechanism is proposed in accordance with known principles of photo activation of tertiary amines. Visible light promoted C(sp3)-H functionalization of N-aryl-protected tetrahydroisoquinolines and N-aryl-protected tetrahydro-β-carbolines in microflow conditions via a-amino radical pathway with various coupling partners in excellent yields and efficiencies.
可见光促进了由环状叔胺化合物形成α-氨基自由基，并使其在流动条件下随后加成到迈克尔受体上，从而能够合成多种官能化的N-芳基取代的四氢异喹啉（THIQs）和N-芳基取代的四氢-β-咔啉（THBCs）。可见光与Ru(bpy)Cl光催化剂结合，能在室温下的流动条件下形成α-氨基自由基并具有高反应活性。这些反应高效地生成了有价值的产物；一些在光或热反应条件下以前无法实现的反应途径；例如，通过α-氨基自由基途径直接合成1-取代的（THBCs）在流动体系中成功实现。事实证明，使用定制的FEP管微反应器是在流动体系中成功形成α-氨基自由基和实现整体反应性能的关键。测试了三种类型的透光定制微流控装置，其中玻璃/硅和FEP型反应器在测试化合物的转化方面显示出非常好的结果。根据叔胺光活化的已知原理提出了合理的反应机理。在微流条件下，可见光通过α-氨基自由基途径促进了N-芳基保护的四氢异喹啉和N-芳基保护的四氢-β-咔啉与各种偶联伙伴的C(sp3)-H官能化反应，产率和效率都很高。
