Novel synthesis of arylboronic acids by electroreduction of aromatic halides in the presence of trialkyl borates

Synthetic Organic Electrochemical Methods Since 2000: On the Verge of a Renaissance

“…731,732 Analogous to the allyl halide borylation reaction discussed in the preceding section, borylation of aryl halides can be accomplished through cathodic reduction of aryl halides in the presence of a boron electrophile. Pinacol borane 634,702 and trialkyl borates 701,703 have both been employed for such transformations. The use of the former allows the preparation of potassium trifluoroborates in one pot (Figure 43A).…”

“…When unsymmetrical allyl halides are used, the terminal allyl boronic ester was afforded. Borylation of aryl halide has also been reported and will be discussed in the section on aryl halide reduction. − Additionally, electrochemical reduction of allyl halides has also found applications in conjugate additions with α,β-unsaturated esters. , …”

New Electrosynthesis of Arylboronic Esters from Aromatic Halides and Pinacolborane

“…The use of trialkyl borates for the electrosynthesis of arylboronic acids has been reported to occur in moderate yields. [7] We report here a novel coupling reaction, based on the use of pinacolborane (HBpin) as an efficient reagent for the electrochemical functionalisation of aryl halides under mild conditions. To our knowledge, no electrochemical reaction with HBpin or analogous boranes has yet been reported.…”

Anodic carbon–boron bond cleavage through the intermediacy of electrogenerated bromonium ion

“…Recently, the anodic acetoxylation of organoborate salts and fluorination of boronic acid derivatives [10] were reported, as well as the electrochemical synthesis of arylboronic acids and esters [11].…”