Metal-Free Electrocatalytic Aerobic Hydroxylation of Arylboronic Acids

Abstract

Hydroxylation of arylboronic acids to aryl alcohols was realized by a scalable electrocatalytic method. The present electrochemical hydroxylation employs low-cost methyl viologen as an organic cathodic electrocatalyst and involves O as a green and sustainable reactant. The electrochemical kinetic studies shown here can be a powerful tool to gain rich mechanistic and kinetic information and thus an in-depth understanding of the electrocatalytic mechanism.

A synthetic chemist's guide to electroanalytical tools for studying reaction mechanisms

“…Since the determination of the order of a reaction with respect to a given substrate in this manner allows identification of the rate-limiting step in catalysis,31 these techniques enable the postulation of reaction mechanisms. Recently, Costentin and Savéant developed a rigorous technique to study the benchmarking and optimisation of molecular catalysts by examining thermodynamic and/or kinetic correlations between properties such as turnover frequency and overpotential 32.…”

Recent Advances in Green Synthesis of Functionalized Phenols from Aromatic Boronic Compounds

“…In 2018, Liu and co‐workers developed a scalable electrocatalytic method for hydroxylation of aryl boronic acids to phenols (Scheme b) . The reaction employs low‐cost methyl viologen (MV) as an organic cathodic electrocatalyst and O 2 in air as a green and sustainable oxidant.…”

A Green Alternative for the Conversion of Arylboronic Acids/Esters into Phenols Promoted by a Reducing Agent, Sodium Sulfite

“…As alternatives, many protocols require an excess of strong oxidants such as hydrogen peroxide, meta ‐chloroperoxybenzoic acid, ammonium persulfate, organic hypervalent iodine, sodium chlorite, N ‐oxides or oxone® . Although the synthesis of phenols from arylboronic acids has been performed using photo‐redox catalysis and electrocatalysis in the presence of molecular oxygen as ultimate oxidant, these approaches require several hours to achieve full conversion. Also, phenols can be obtained using different reducing agents such as thiol and hydrazine derivatives .…”