Metal-Free Perfluoroarylation by Visible Light Photoredox Catalysis

• Published in: ACS catalysis 2016-01, Vol.6 (1), p.369-375
• Main Authors: Meyer, Andreas U, Slanina, Tomáš, Yao, Chang-Jiang, König, Burkhard
• Format: Article
• Language: English
• ISSN: 2155-5435; 2155-5435
• DOI: 10.1021/acscatal.5b02410

Visible light and eosin Y catalyze the direct arylation of simple arenes with fluorinated aryl bromides by a photoredox process. The reaction scope is broad in fluorinated compounds and arenes and the general and simple procedure provides a metal-free alternative for the synthesis of synthetically valuable polyfluorinated biaryl structures. The mild reaction conditions allow a selective reaction with the alkaloid brucine without protection of functional groups illustrating the potential of the process for late stage functionalization. Mechanistic investigations reveal the photoreduction of eosin Y via its triplet state by triethylamine and subsequent electron transfer from the eosin Y radical anion to the polyfluorinated bromoarene, which fragments into the polyfluorinated aryl radical and a bromide anion. A radical chain reaction mechanism was excluded by a quenching factor analysis.