IPSO-Hydroxylation of Boronic Acid via Ozonolysis: A Metal-, Ligand-, and Base-free Method

Imidazolium-urea low transition temperature mixtures for the UHP-promoted oxidation of boron compounds

“…Even though choline chloride and/or urea seemed to promote the reaction under metal-free conditions, the reaction takes place in an aqueous solution rather than in the LTTM, since both components (ChCl and urea) are solvated by water due to the big excess used relative to them (>125 mmol of water per 0.1 mmol of ChCl/U) [27]. Nevertheless, this methodology represented a step up on other described procedures, which rely on transition metal catalysis [26], costly [37] or unwieldy [38] reagents, and stoichiometric amounts of additives [39][40][41][42][43]. What is more, these procedures use a large excess of aqueous H 2 O 2 , which tends to slowly decompose over time spoiling the reagent [44].…”

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.…”

N-Substituted 3(10H)-Acridones as Visible-Light, Water-Soluble Photocatalysts: Aerobic Oxidative Hydroxylation of Arylboronic Acids

“…Recently, the hydroxylation of arylboronic acid was considered as an effective method to furnish phenols. To date, various reaction conditions to realize the hydroxylation of arylboronic acid have been developed as follows: (1) using transition-metal catalysts such as copper, palladium, gold, ruthenium, or silver, either in the presence of a strong base or under base-free conditions; (2) using stoichiometric amounts of oxidants such as hydrogen peroxide, TBHP, m -CPBA, oxone, hydroxylamine, amine oxide, ozone, PhI­(OAc) 2 , benzoquinone, and NaClO 2 ; (3) electrochemical reactions; (4) aerobic oxidative hydroxylation using organocatalysis and photocatalysts such as ruthenium complex, iron complex, methylene blue, quinine, and 2-chloroanthraquinone …”