Highly Efficient Synthesis of Phenols by Copper-Catalyzed Oxidative Hydroxylation of Arylboronic Acids at Room Temperature in Water

Abstract

A general and efficient procedure for the preparation of phenols was developed by copper-catalyzed oxidative hydroxylation of arylboronic acids at room temperature in water.

Highly Efficient Aerobic Oxidative Hydroxylation of Arylboronic Acids: Photoredox Catalysis Using Visible Light

“…[17] To the best of our knowledge, this is the first example of oxidative hydroxylation of arylboronic acids using a visible-light photocatalytic strategy.…”

General Copper‐Catalyzed Transformations of Functional Groups from Arylboronic Acids in Water

“…Aryl boron compounds are common chemicals and they are easily prepared from readily available aryl halides (such as aryl bromides and chlorides) and tosylates [14] or by iridium-catalyzed direct borylations of arenes through C À H bond activation. [15] The aryl boron compounds have been used as the starting materials to make aromatic compounds containing various functional groups (including aryl halides, [16] aryl azides, [17] aryl sulfones, [18] phenols, [19] arylamines developed by us [20] and nitroarenes [21] ) through an aerobic oxidative strategy. [22] Unfortunately, the methods need the special ligands of catalysts, organic solvents, and specific temperatures, and the limited substrate scope and unrecyclable catalyst systems greatly limit use of these methods.…”

Photocatalytic hydroxylation of arylboronic acids using continuous flow reactors

“…With [Ru(bpy) 3 ] 2+ , the efficiency with both reductive quenchers was high, however, as with Rose Bengal, the amine gave superior conversion (entries 1 and 3). In order to optimise the reaction, we tested the efficiency of both photocatalysts with the amine as the reductive quencher under similar conditions.…”

“…[3][4][5][6] Although direct boronic acid hydroxylation has received attention, it oen requires the use of strong oxidising agents or toxic metal catalysts. 3,[7][8][9][10][11][12][13][14] Recently, a number of alternative methods have been described, based on the generation of superoxide free radical species (O 2 c À ). 15,16 In this context, photocatalysis has emerged as a promising methodology [17][18][19] which is compatible with a variety of substrates and catalysts, including metal-free dyes.…”