Benign Perfluoroalkylation of Aniline Derivatives through Photoredox Organocatalysis under Visible-Light Irradiation

• Published in: European journal of organic chemistry 2015-12, Vol.2015 (36), p.7869-7875
• Main Authors: Barata-Vallejo, Sebastián, Yerien, Damian E., Postigo, Al
• Format: Article
• Language: English
• Subjects: Aromatic substitution; Organocatalysis; Perfluoroalkylation; Photocatalysis; Radical reactions
• ISSN: 1434-193X; 1099-0690
• DOI: 10.1002/ejoc.201501189

In this work, we present a room‐ or solar‐light‐initiated transition‐metal‐free radical homolytic aromatic substitution (HAS) reaction of aniline derivatives with perfluoroalkyl moieties employing perfluoroalkyl halides as readily available perfluoroalkyl sources in the presence of cesium carbonate as base and inexpensive Rose Bengal as organophotocatalyst in MeCN as solvent, rendering perfluoroalkyl‐substituted aniline derivatives in good‐to‐excellent yields, even upon scaling up. Although the mechanism of this reaction is still under investigation, we shall present some evidence based on competitive substitution rate experiments that cast some light onto the reaction intermediates. We have developed a photocatalytic CAr–Rf bond formation reaction by homolytic aromatic substitution (HAS) with an inexpensive organic dye, Rose Bengal, in the absence of transition metals, through irradiation at ambient temperature with visible light by using readily available perfluoroalkyl halides. This method was applied to the synthesis of a variety of perfluoroalkyl‐substituted aniline derivatives.