关键词: 光催化, 半导体光催化剂, 氧化还原介体, 2-异腈基联苯, 氟烷基化反应

The strategic incorporation of fluoroalkyl moieties into organic architectures, commonly referred to as fluoroalkylation, has emerged as a transformative methodology in synthetic chemistry over recent decades. By introducing the fluoroalkyl group, the altered chemical and physical properties could lead to biological and pharmacological benefits, such as greater lipophilicity, enhanced metabolic stability, and bioavailability. Among various fluoroalkylation agents, sodium fluoroalkylsulfinates have emerged as particularly promising reagents owing to their cost-effectiveness, commercial accessibility, and versatile utility in diverse synthetic methodologies. Phenanthridine is one of the most vital fused N-heterocycles frequently found in a range of natural products, synthetic pharmaceuticals and valuable materials. Among numerous phenanthridine derivatives, 6-fluoroalkylphenanthridines display a wide spectrum of interesting biological activities and physicochemical properties. The radical fluoroalkylation of 2-isocyanobiaryls has been considered as an efficient and atom-economic strategy for the rapid construction of 6-fluoroalkylphenanthridine compounds. Visible-light photocatalysis has become a highly versatile tool in green organic synthesis, which employs inexhaustible visible light energy to promote the organic transformations under very mild conditions. The redox-mediated intrinsic semiconductor photocatalysis, which fully utilized the photo-generated electrons and holes for the organic transformation process, leading to not only solving the inherent limitations of intrinsic semiconductor catalysis but also improving the catalytic efficiency of organic transformation. In the present work, we report the development of redox-mediated intrinsic semiconductor photocatalytic semi-heterogeneous fluoroalkylation of 2-isocyanobiaryls with sodium fluoroalkylsulfinates. With CeO₂ as the heterogeneous photocatalyst, diphenyl ether as the homogeneous redox mediator, dimethyl sulfoxide (DMSO) as the solvent, a series of 6-fluoroalkyl-phenanthridines were efficiently synthesized. The CeO₂ was easily recovered from the reaction mixture and reused several times, paving the way for larger-scale industrial applications of this type of photocatalytic fluoroalkylation reactions.

Key words: visible-light photocatalysis, semiconductor photocatalyst, redox mediator, 2-isocyanobiaryl, fluoroalkylation