Electrochemical Hydroxylation of Electron-Rich Arenes in Continuous Flow

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.