Electrochemical Technique and Copper-Promoted Transformations: Selective Hydroxylation and Amination of Arylboronic Acids

Abstract

An efficient and selective electrosynthesis of phenols and anilines from arylboronic acids in aqueous ammonia is achieved in an undivided cell. By simply changing the concentration of aqueous ammonia and the anode potential, good yields of phenols and anilines can be obtained chemoselectively with high reaction rates. We propose that anodic oxidation could have played an important role in these transformations.

Transition Metal‐Free ipso‐Functionalization of Arylboronic Acids and Derivatives

“…[22] A variety of phenols from arylboronic acids in aqueous ammonia were generated efficiently in an undivided cell. The formation of phenols versus anilines could be controlled with good chemoselectivity by simply changing the aqueous ammonia concentration and the anode potential.…”

Aerobic photooxidative hydroxylation of boronic acids catalyzed by anthraquinone-containing polymeric photosensitizer

“…Oxidative hydroxylation of boronic acids is one of the most important methods for the synthesis of phenols or alcohols. [1][2][3][4][5][6][7] Strong oxidants such as ozone, 8 high-valence halogen compounds, [9][10][11] peroxides and N-oxides 12 are efficient reagents for such transformations (Scheme 1a). However, these methods generate large amounts of wastes detrimental to the environment.…”

ipso‐Hydroxylation of Arylboronic Acids and Boronate Esters by Using Sodium Chlorite as an Oxidant in Water

“…To improve this transformation, I 2 ,7d acidic Al 2 O 3 ,7e and Amberlite IR‐120 resin7f have been used as catalysts with H 2 O 2 and complexes of poly( N ‐vinylpyrrolidone)/hydrogen peroxide and poly(4‐vinylpyridine)/hydrogen peroxide 7g. Other catalysts/reagents used for the transformation of arylboronic acids into phenols include CuSO 4 /phenanthroline,7h NH 2 OH/NaOH,7i potassium peroxymonosulfate,7j photoredox catalysis with the use of visible light,7k and N ‐oxides,7l but the search for better methods still continues 7m,7n. Most of the reported methods are not free from drawbacks such as the use of transition metals with ligands,7h harsh reaction conditions,7j long reaction times,7i chlorinated organic solvents as reaction media,7l and expensive reagents 7k.…”