Electrochemical Hydroxylation of Electron‐Rich Arenes in Continuous Flow. Issue 20 (5th April 2022)

• Record Type: Journal Article
• Authors: Kooli, Anni; Wesenberg, Lars; Beslać, Marko; Krech, Anastasiya; Lopp, Margus; Noël, Timothy; Ošeka, Maksim
• Is Part Of: European journal of organic chemistry. Volume 2022:Issue 20(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-04-05
• Subjects: Aromatic substitution -- Electrolysis -- Flow chemistry -- Hydroxylation; Chemistry, Organic -- Periodicals; Organic compounds -- Synthesis -- Periodicals; Bioorganic chemistry -- Periodicals; Chemistry, Physical organic -- Periodicals; 547
• DOI: 10.1002/ejoc.202200011
• Languages: English
• ISSNs: 1434-193X

Abstract

Abstract: Electrochemical hydroxylation of arenes by trifluoroacetic acid provides a straightforward access to aryl oxygen compounds under the mild and environmental benign reaction conditions. Harmful and pollutant stoichiometric amounts of oxidation reagents and the use of metal‐catalysts can be avoided. Herein, we present a novel method for the synthesis of hydroxylated products from electron‐rich arenes that was achieved by the implementation of a continuous‐flow setup. The continuous nature of the process allowed to fine‐tune the reactions conditions in order to prevent the decomposition of the sensitive products expanding the reaction scope beyond electron‐poor and neutral arenes that were previously reported in the batch processes. Thus, synthetically valuable hydroxylated arenes were obtained in good yields with the residence time just over a minute. In order to demonstrate the reliability and the efficiency of the electrochemical flow setup, a scale up experiment was also performed. Abstract : An electrochemical approach for the hydroxylation of electron‐rich arenes was developed. The transformation relies on the anodic oxidation of arene and the use trifluoroacetic acid as an oxygen source. The reaction is carried out in an electrochemical flow reactor, which allowed to synthesize sensitive products by shortening reaction/residence time to 1.25 minutes and to perform a scale up experiment.