Molecular Iodine as a Catalyst for Alkene Difluorination
Tsugio Kitamura*, Juzo Oyamada, Masahiro Higashi, Yosuke Kishikawa
*Department of Chemistry and Applied Chemistry, Saga University, Saga 840-8502, Japan,
Email: kitamura
cc.saga-u.ac.jp
T. Kitamura, J. Oyamada, M. Higashi, Y. Kishikawa, J. Org. Chem., 2024, 89, 5896-5900.
DOI: 10.1021/acs.joc.4c00179
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Abstract
Iodine catalyzes a simple and practical difluorination reaction of alkenes. The reaction can be applied to many aliphatic and aromatic alkenes bearing synthetically useful functional groups, such as ester, amide, hydroxy, and aryl groups.
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proposed mechanism
Details
The document discusses a novel catalytic difluorination reaction of alkenes using molecular iodine (I2) as a catalyst. This method offers a practical and efficient alternative to traditional fluorination techniques, which often involve toxic and difficult-to-handle reagents like fluorine gas. The study reveals that I2, in the presence of an oxidizing agent (Selectfluor) and an HF reagent (TEA·5HF), can catalyze the difluorination of both aliphatic and aromatic alkenes. The reaction proceeds through two catalytic cycles: one involving the formation of an IF adduct and its subsequent oxidation to difluoroiodane, and another where the IF adduct itself acts as a catalyst. The optimized conditions for the reaction include using 10 mol % I2 at 60°C, yielding vic-difluorinated products for aliphatic alkenes and gem-difluorinated products with aryl group rearrangement for aromatic alkenes. This new methodology is cost-effective and simple, making it appealing for synthesizing fluorine-containing compounds, which are significant in pharmaceuticals, agricultural chemicals, and functional materials. The study's findings suggest a new type of catalytic fluorination reaction, potentially leading to further developments in organic chemistry.
Key Words
1,2-difluoroalkanes, Selectfluor
ID: J42-Y2024
