Tetrahydroxydiboron (Bis‐boric Acid): a Versatile Reagent for Borylation, Hydrogenation, Catalysis, Radical Reactions and H₂ Generation

Abstract

Diboron compounds with a BÀ B bond, discovered with B 2 Cl 4 a century ago, have been developed only since the turn of this century for catalyzed borylation reactions, mostly with the wellknow reagent bis(binacolato)diboron, (B 2 pin 2 ). On the other hand, chemistry of tetrahydroxydiboron (THDB), also named bis-boric acid, is relatively underdeveloped. In this review, the properties of THDB as a borylation, reductant (including transfer hydrogenation), catalyst, source of radicals and generator of H 2 from water upon hydrolysis are summarized.

From sandwich complexes to dendrimers: journey toward applications to sensing, molecular electronics, materials science, and biomedicine

“…195 In the particular case of the nanocatalyzed hydrolysis of bis-boric acid, {B 2 (OH) 4 }, however, both hydrogen atoms of H 2 formed are coming from water, the side product being boric acid, B(OH) 3 . 207,217 The H 2 generation reaction rates can be switched on and off for instance by pH control, 212,215,217 or be boosted by visible-light irradiation, either upon including a semiconductor in the nanocatalyst composite (Mott-Schottky junction at the metal-semiconductor interface), 211 or more efficiently utilizing the Ag or Au plasmon [207][208][209][215][216][217][218][219] or a combination of both the semiconductor and plasmonic effects. 211 The studies of these nanocatalysts bring about considerable knowledge on how the key nanocatalyst hydride are formed and how they reductively eliminate to give H 2 .…”

Recent Expedition in Pd‐ and Rh‐Catalyzed C(Ar)−B Bond Formations and Their Applications in Modern Organic Syntheses

“…Aryl bromides, and more challenging aryl chlorides were found applicable to give the borylated products in moderate‐to‐good yields under this reaction protocol. The use of tetrahydroxydiboron for borylation reaction was summarized by Liu and Astruc in 2023 [19] …”

“…The use of tetrahydroxydiboron for borylation reaction was summarized by Liu and Astruc in 2023. [19] A commercially available SiliaCat DPPÀ Pd was used to facilitate the coupling between aryl iodides/bromides and bis(pinacolato)diboron for delivering a wide range of boronic acid pinacol esters (Scheme 1a). [20] Good-to-excellent yield of borylated products (up to 98 %) were obtained from (hetero)aryl bromides.…”

Transfer Hydrogenolysis of O‐ and N‐Benzyl Groups in Water with Tetrahydroxydiboron by Using an Amphiphilic Polymer‐Supported Nano‐Palladium Catalyst

“…Tetrahydroxydiboron [B 2 (OH) 4 ] has been gaining significant attention as a versatile reducing agent in organic synthesis. [5][6][7][8][9][10][11] Recently, we and other research groups have reported that B 2 (OH) 4 reduces various functional groups such as alkenes, alkynes, [7] heteroarenes, [7b,8] aryl halides, [7c] aryl ketones, [9] and nitroarenes [7d,8,10] in the presence of transition-metal catalysts. It has also been reported that the B 2 (OH) 4 -promoted reductions often proceed through transition-metal-catalyzed transfer hydrogenation from water under aqueous conditions.…”