Hydroxylation Of Arylboronic Acids Research Articles

Green Synthesized Biogenic Ag Nanoparticles With Enhanced Antibacterial, Antifungal, Antibiofilm, and Antioxidant Activities: Catalytic Applications in the ipso‐Hydroxylation of Aryl Boronic Acids

Green Synthesized Biogenic Ag Nanoparticles With Enhanced Antibacterial, Antifungal, Antibiofilm, and Antioxidant Activities: Catalytic Applications in the <i>ipso</i>‐Hydroxylation of Aryl Boronic Acids

Ni2P Anchored on Barbituric Acid-Modified Graphitic Carbon Nitride as a Versatile Photocatalyst for Hydroxylation of Aryl Boronic Acids and Oxidation of Benzyl Alcohols

Ni₂P Anchored on Barbituric Acid-Modified Graphitic Carbon Nitride as a Versatile Photocatalyst for Hydroxylation of Aryl Boronic Acids and Oxidation of Benzyl Alcohols

Hydroxylation of Arylboronic Acids by COFs Prepared by a Photocatalytic Multicomponent Reaction

Key words covalent organic frameworks - photocatalysis - hydroxylation - arylboronic acids - phenols

Surface Nanoarchitectonics of Boron Nitride Nanosheets for Highly Efficient and Sustainable ipso-Hydroxylation of Arylboronic Acids.

One of the important industrial processes commonly employed in the pharmaceutical, explosive, and plastic manufacturing industries is ipso-hydroxylation of arylboronic acids. In this work, a straightforward, metal-free methodology for the synthesis of phenols from arylboronic acids has been demonstrated using hydroxyl functionalized boron nitride (BN-OH) nanosheets. The functionalized hydroxyl groups on the BN nanosheets act as the active sites for the hydroxylation reaction to take place. The detailed optimization of reaction parameters was done in order to attain high catalytic efficiency, and the reactions were conducted in water, which eliminates the use of toxic solvents. The as-synthesized catalysts exhibited excellent recyclability and reusability in addition to high product yields and good turnover numbers. The green metrics parameters were also evaluated for the model reaction to examine the sustainable nature of the developed protocol. The use of BN-OH catalysts for the ipso-hydroxylation reactions under base-free and metal-free conditions using environmentally benign solvents is utmost desired for industrial processes and can pave a way toward sustainable organic catalysis.

Pyrene-Based D-A Molecules as Efficient Heterogeneous Catalysts for Visible-Light-Induced Aerobic Organic Transformations.

In this work, an efficient visible light promoted aerobic dehydro-coupling of amines, oxidation of thioethers and hydroxylation of arylboronic acids under benign conditions by using pyrene-based donor-acceptor (D-A) conjugated organic molecules was described. Donor-acceptor structure influences their π-conjugation and band gap a lot, and thereby enhances their visible light absorption ability, single electron transfer and oxidative behaviors. Alkynyl units in PS-IV play a crucial role in the catalyst which could serve as electron transferring bridge to strengthen electron delocalization, thus facilitating the single electron transfer from photosensitizer to substrates, and making it an efficient ⋅O2 - generator. While PS-III without alkynyl units tends to produce 1 O2 . Therefore, these molecules can serve as efficient catalysts for different kinds of visible-light-induced aerobic organic reactions. More importantly, the simply structured molecule is insoluble and stable in various solvents, and thus could be recycled as heterogeneous catalyst for many rounds with slight catalytic activity degradation. Besides, large scale (1 mol) reaction of benzylamine coupling proceeded smoothly under the standard conditions.

A Doubly Interpenetrated Cu(II)‐based Metal‐Organic Framework as a Heterogeneous Catalyst for the ipso‐Hydroxylation of Arylboronic Acids

AbstractA doubly interpenetrated Cu(II)‐organic framework with formula [{Cu2(L)2(4,4′‐bpdc)2(H2O)2} ⋅ 8H2O ⋅ CH3OH]α (1) (where, L=N2, N6‐di(pyridin‐4‐yl)naphthalene‐2,6‐dicarboxamide and 4,4′‐bpdc=[1,1′‐biphenyl]‐4,4′‐dicarboxylate ion) has been synthesized and characterized with the help of several spectroscopic and analytical techniques including single crystal X‐ray analysis. A single crystal X‐ray analysis reveals that 1 exhibit interpenetrated two‐dimensional sheet‐like structure containing elongated channels of cross‐section 11.09×31.22 Å2 along the a‐axis. Finally, 1 has been exploited as a heterogeneous catalyst for the ipso‐hydroxylation of arylboronic acids yielding up to 99 % of the respective phenolic product. Importantly, the catalyst can be reused for five successive cycles without having a significant loss in its catalytic efficiency.

Dye-Sensitized TiO2 as Heterogenous Visible Light Photocatalyst for the Hydroxylation of Aryl Boronic Acids

Herein, we report the preparation of a variety of dye-sensitized TiO2 and its application as a heterogeneous photocatalyst for the oxidative hydroxylation of boronic acids and esters to synthesize phenols. Several organic dyes, namely eosin Y, rose bengal, purpurin, alizarin blue, fluorescein and riboflavin were combined with TiO2. The nanohybrid TiO2-eosin Y showed the best results. Furthermore, we demonstrated a synergistic association between dyes and TiO2 that improves its photocatalytic properties. This methodology resulted compatible for aryl boronic acids with both electron-withdrawing and electron donor groups on the aromatic ring. Thus, the reactions were performed under heterogeneous photocatalytic conditions, employing visible light, saturated oxygen atmosphere, short reaction time, acetonitrile and water as environmentally friendly solvents, to produce the corresponding phenols in very good to excellent isolated yields. Finally, we proposed a mechanism where the selective excitation of EY associated with TiO2 using visible light and the formation of the superoxide anion play a main role in this reaction.

Copper Sulfide Nanosheets for Photocatalytic Oxidation of Benzyl Alcohols and Hydroxylation of Arylboronic Acids

Copper Sulfide Nanosheets for Photocatalytic Oxidation of Benzyl Alcohols and Hydroxylation of Arylboronic Acids

Coordination Polymers as a Functional Material for the Selective Molecular Recognition of Nitroaromatics and ipso‐Hydroxylation of Arylboronic Acids

We report the synthesis and structural characterization of two coordination polymers (CPs), namely; [{Zn(L)(DMF)4 } ⋅ 2BF4 ]α (1) and [{Cd(L)2 (Cl)2 } ⋅ 2H2 O]α (2) (where L=N2 ,N6 -di(pyridin-4-yl)naphthalene-2,6-dicarboxamide). Crystal packing of 1 reveals the existence of channels running along the b- and c-axis filled by the ligated DMF and lattice anions, respectively. Whereas, crystal packing of 2 reveals that the metallacycles of each 1D chain are intercalating into the groove of adjacent metallacycles resulting in the stacking of 1D loop-chains to form a sheet-like architecture. In addition, both 1 and 2 were exploited as multifunctional materials for the detection of nitroaromatic compounds (NACs) as well as a catalyst in the ipso-hydroxylation of aryl/heteroarylboronic acids. Remarkably, 1 and 2 showed high fluorescence stability in an aqueous medium and displayed a maximum 88% and 97% quenching efficiency for 4-NPH, respectively among all the investigated NACs. The mechanistic investigation of NACs recognition suggested that the fluorescence quenching occurred via electron as well as energy transfer process. Furthermore, the ipso-hydroxylation of aryl/heteroarylboronic acids in presence of 1 and 2 gave up to 99% desired product yield within 15 min in our established protocol. In both cases, 1 and 2 are recyclable upto five cycles without any significant loss in their efficiency.

Hydroxylation of Arylboronic Acids to Phenols on a Vanadia–Titania Catalyst

Hydroxylation of Arylboronic Acids to Phenols on a Vanadia–Titania Catalyst

Deep eutectic solvent mediated controlled and selective oxidation of organic sulfides and hydroxylation of arylboronic acids

A mild and efficient protocol has been developed for the controlled oxidation of wide variety of organic sulfides to corresponding sulfoxides using deep eutectic solvent (DES) as catalyst and hydrogen peroxide as oxidant under ambient condition. In presence of benzyl alcohols along with sulfides, DES selectively oxidizes only the sulfides to corresponding sulfoxides. The DES is prepared by using zirconium oxychloride and urea (1:5 ​M ratio) which is thermally stable up to 213 ​°C. The prepared DES can also be effectively applied for hydroxylation of arylbronic acids without using any additional catalyst and solvent.

Synthesis of Phenols via Metal-Free Hydroxylation of Aryl Boronic Acids with Aqueous TBHP

An alternate procedure for oxidative hydroxylation of aryl boronic acids with aqueous TBHP to access phenols is described. The protocol tolerated various functional groups substituted with aromatic rings. The reaction was performed in water and free from transition metal oxidants.

Recyclable Cu@C3N4-Catalyzed Hydroxylation of Aryl Boronic Acids in Water under Visible Light: Synthesis of Phenols under Ambient Conditions and Room Temperature

A heterogeneous photocatalyst based on copper-doped g-C3N4 was developed for the oxidative hydroxylation of aryl boronic acids into phenols at room temperature under the irradiation of blue light (...

A Green Alternative for the Conversion of Arylboronic Acids/Esters into Phenols Promoted by a Reducing Agent, Sodium Sulfite

Hydroxylation of arylboronic acids and arylboronic esters using sodium sulfite and oxygen as the source of ultimate oxidant proceeds rapidly in water under transition metal‐free conditions. This remarkable mild and environmentally benign protocol represents a green alternative to synthesize phenols using inexpensive starting materials in a simple methodology. This new application for sodium sulfite shows a wide tolerance of functional groups, and it is compatible with oxidizable functionalities.

Graphene Oxide as a Carbocatalyst for Sustainable ipso-Hydroxylation of Arylboronic Acids: A Simple and Straightforward Strategy To Access Phenols

A metal-free and straightforward protocol for the synthesis of phenols from aryl and heteroaryl boronic acids has been demonstrated using graphene oxide as a carbocatalyst. This sustainable ipso-hy...

Chemically Modified Chitosan as a Biopolymer Support in Copper‐catalyzedipso‐Hydroxylation of Arylboronic Acids in Water

Figure S1. IR spectra of Chitosan (CTS), CTS-Py (L1), and CTS-Th (L2). Figure S2. TGA Thermograms of (a) L1 and (b) L2. Figure S3. SEM images of (a) L1 before use, (b) L1 after use, (c) L2 before use, and (d) L2 after use. Figure S4. IR spectra of L1 (before and after). Table S1. Optimization of reaction conditions. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Phthalocyanine Zinc‐catalyzed Hydroxylation of Aryl Boronic Acids under Visible Light

AbstractA visible‐light‐promoted aerobic oxidative hydroxylation of boronic acids using phthalocyanine zinc as an easily available photosensitizer has been developed. It provided a direct access to synthesize aliphatic alcohols and phenols from boronic acids. The advantages of this approach included the low catalyst loading (0.5 mol%), high efficient, the use of O2 as an oxygen source, wide substrate range, the simple operational process, and mild conditions.magnified image

Cationic Polycarbazole Networks as Visible-Light Heterogeneous Photocatalysts for Oxidative Organic Transformations

Photoredox catalysis has aroused great interest from chemists, as it offers a powerful tool for organic synthesis. Cationic polycarbazole networks (CPOP-28 and CPOP-29) were prepared via simple oxidative coupling reaction and applied as heterogeneous photocatalysts for a wide range of oxidative organic transformations, including oxidation of sulfides, hydroxylation of arylboronic acids, and cross-dehydrogenative coupling reactions, in the presence of visible light and air. Remarkably, photocatalytic activities are enhanced by ingenious introduction of trifluoromethyl groups to the polymeric network CPOP-29. The effects of the trifluoromethyl group on photocatalytic activities were elucidated in terms of photophysical and electrochemical properties. The appealing photocatalytic performance of the trifluoromethylated polymer is ascribed to superior light-absorption ability, longer fluorescence lifetime, and stronger oxidative capability. In addition, the photocatalysts showed good recyclability and could be...

Pd-Catalyzed Hydroxylation of Aryl Boronic Acids Using In Situ Generated Hydrogen Peroxide.

Herein, we describe a benign and efficient palladium-catalyzed hydroxylation of aryl boronic acids under mild conditions, with in situ generated hydrogen peroxide from carbon monoxide, water, and oxygen. This novel procedure combines catalytic production of hydrogen peroxide with an aerobic oxidation process in a sole reaction system. This system shows good functional group tolerance and provides a benign and efficient access to a variety of functionalized phenols. Furthermore, the in situ generated hydroperoxide can be well used for triphenylphosphine oxidation, in which the TON is up to 194. Isotope labelling studies provide important mechanistic insights for this process.

ChemInform Abstract: Biomimetic Aerobic Oxidative Hydroxylation of Arylboronic Acids to Phenols Catalyzed by a Flavin Derivative.

ChemInform Abstract: Biomimetic Aerobic Oxidative Hydroxylation of Arylboronic Acids to Phenols Catalyzed by a Flavin Derivative.