Aryl Phenols Research Articles

The first report on the utility of an organotellurium compound as a stabilizer in the colloidal synthesis of a transition-metal-containing nanocatalytic system: application to O-arylation of phenol

The application of an organotellurium ligand as a stabilizer of palladium nanoparticles has been reported, and these nanoparticles have the potential to catalyze the O-arylation of phenols, even with aryl chlorides having deactivating substituents.

Copper-catalyzed O-arylation of phenols with diazonium salts

The Cu-catalyzed etherification of phenols with aryl diazonium salts at room temperature afforded diaryl ethers in moderate to excellent yields.

Meta-Selective C-H arylation of phenols via regiodiversion of electrophilic aromatic substitution.

Electrophilic aromatic substitution is among the most widely used mechanistic manifolds in organic chemistry. Access to certain substitution patterns is, however, precluded by intrinsic and immutable substituent effects that ultimately restrict the diversity of the benzenoid chemical space. Here we demonstrate that the established regioselectivity of electrophilic aromatic substitution can be overcome simply by diverting the key σ-complex intermediate towards otherwise inaccessible substitution products. This 'regiodiversion' strategy is realized through the development of a general and concise method for the meta-selective C-H arylation of sterically congested phenols. Consisting of a Bi(V)-mediated electrophilic arylation and a subsequent aryl migration/rearomatization, our process is orthogonal to conventional C-H activation and cross-coupling approaches, and does not require prefunctionalization of the substrate. Mechanistically informed applications in synthesis showcase its utility as a versatile and enabling route to highly functionalized, contiguously substituted aromatic building blocks that defy synthesis via existing methods.

Visible-light-driven C(sp2)-H arylation of phenols with arylbromides enabled by electron donor-acceptor excitation.

We have developed a catalyst-free visible-light-driven C(sp2)-H arylation of unprotected phenols with arylbromides to give 2-arylated phenols. This reaction proceeds through the excitation of an electron donor-acceptor complex between a phenolate and an arylbromide, electron transfer, and debrominative C(sp2)-C(sp2) coupling.

Ortho-selective C-H arylation of phenols with N-carboxyindoles under Brønsted acid- or Cu(i)-catalysis.

Control over chemo- and regioselectivity is a critical issue in the heterobiaryl synthesis via C–H oxidative coupling. To address this challenge, a strategy to invert the normal polarity of indoles in the heterobiaryl coupling was developed. With N-carboxyindoles as umpoled indoles, an exclusively ortho-selective coupling with phenols has been realized, employing a Brønsted acid- or Cu(i)-catalyst (as low as 0.01 mol%). A range of phenols and N-carboxyindoles coupled with exceptional efficiency and selectivity at ambient temperature and the substrates bearing redox-active aryl halides (–Br and –I) smoothly coupled in an orthogonal manner. Notably, preliminary examples of atropselective heterobiaryl coupling have been demonstrated, based on a chiral disulfonimide or a Cu(i)/chiral bisphosphine catalytic system. The reaction was proposed to occur through SN2′ substitution or a Cu(i)–Cu(iii) cycle, with Brønsted acid or Cu(i) catalysts, respectively.

Functionalization of graphene oxide with a hybrid P, N ligand for immobilizing and stabilizing economical and non-toxic nanosized CuO: an efficient, robust and reusable catalyst for the C–O coupling reaction inO-arylation of phenol

A new graphene oxide based heterogeneous catalytic system holding CuO nanoparticles through P and N donor sites for the C–O coupling reaction.

Organosulphur and organoselenium compounds as emerging building blocks for catalytic systems forO-arylation of phenols, a C–O coupling reaction

Diaryl ethers form an important class of organic compounds.

Palladium-Catalyzed Cascade Allylative Dicarbofunctionalization of Aryl Phenol-Tethered Alkynes with Allyl Iodides: Synthesis of Skipped Dienes.

A palladium-catalyzed cascade allylative dicarbofunctionalization of aryl phenol-tethered alkynes with allyl iodides is described. A series of polysubstituted spirocyclo-containing skipped dienes with an all-carbon tetrasubstituted alkene unit are synthesized through this convenient process. The cascade reaction proceeds selectively through dearomative C-allylation instead of O-allylation of aryl phenols.

New Approach for the Synthesis of Aryloxy 1,3-Oxazines

Oxazinne compounds have drew the attention of many researchers to find different approaches to the synthesis of this type of compounds according to the success of their use in a wide range of pharmaceutical application during the last decades .It is also for the difference reactivity of these analogues is exhaustively depicted and illustrates the rich versatility of this class of starting material. They proved to have most of actions of a combination of other drugs. We are herein investigate the synthesis of ethyl aryloxy acetate(S1-6) from the reaction of the corresponding ethyl bromo acetate with aryl phenols .These intermediates were cyclized with antharanilic acid affording the titled compounds

NEW APPROACH FOR THE SYNTHESIS OF ARYLOXY 1,3-OXAZINES

Oxazine compounds have drew the attention of many researchers to find different approaches to the synthesis of this type of compounds according to the success of their use in a wide range of pharmaceutical application during the last decades .It is also for the difference reactivity of these analogues is exhaustively depicted and illustrates the rich versatility of this class of starting material. They proved to have most of actions of a combination of other drugs. We are herein investigate the synthesis of ethyl aryloxy acetate(S1-6) from the reaction of the corresponding ethyl bromo acetate with aryl phenols .These intermediates were cyclized with antharanilic acid affording the titled compounds

Bismuth(V)-Mediated C–H Arylation of Phenols and Naphthols

AbstractWe recently reported a general and practical strategy for the Bi(V)-mediated C–H arylation of phenols and naphthols. Our telescoped protocol proceeds via transmetallation from readily available arylboronic acids to a stable Bi(III) precursor, oxidation to a reactive Bi(V) intermediate, and subsequent ortho-selective phenol arylation. The process exhibits broad scope with respect to both components and tolerates functionality that is incompatible with conventional cross-coupling methods. Preliminary investigations provide insight into the mechanism of each key reaction step.1 Introduction2 Design of a Modular and Practical Arylating System3 B-to-Bi Transmetallation: Scope and Mechanism4 Oxidative C–H Arylation: Exemplification and Mechanism5 Conclusionsions

Bismacycles for the Selective C–H Arylation of Phenols and Naphthols

Key words phenols - naphthols - bismuth - boron - arylation

Efficient Pyrazole Moiety‐Containing Ligands for Cu‐Catalyzed O‐Arylation of Phenols

AbstractSeven pyrazole‐ or pyridine‐containing N2‐ and N3‐ligalitnds (L1–L7) were developed for the ligand‐assisted CuI‐catalyzed coupling reactions of aryl halides with phenols. The structural and electronic effects were studied for various combinations of pyridine and/or imine nitrogen binding sites in the ligands. Screening their abilities showed most of them to be better than 4,4’‐dimethoxybipyridine (L8). Among them, 2‐(1‐pyrazolyl)pyridine (L1) featuring two types of binding sites gave the best results, with yields of up to 95% at 100 °C at a catalyst loading of 10 mol% (CuI/L in 1 : 1 ratio). Free radical scavengers, 2,2,6,6‐tetramethylpiperidin‐1‐yl)oxyl (TEMPO) (1.0 eq.) and cumene (1.0 eq.), lowered the yields by more than half, but the reaction was not completely quenched even when 3.0 eq. of TEMPO was used. A non‐radical and a radical mechanisms, are proposed for the L1‐promoted coupling reaction, well explained the experiments results. In addition, the structure of the catalyst species were elucidated through single crystal XRD and DFT (density functional theory) calculations.

Modular bismacycles for the selective C-H arylation of phenols and naphthols.

Given the important role played by 2-hydroxybiaryls in organic, medicinal and materials chemistry, concise methods for the synthesis of this common motif are extremely valuable. In seeking to extend the lexicon of synthetic chemists in this regard, we have developed an expedient and general strategy for the ortho-arylation of phenols and naphthols using readily available boronic acids. Our methodology relies on in situ generation of a uniquely reactive Bi(V) arylating agent from a bench-stable Bi(III) precursor via telescoped B-to-Bi transmetallation and oxidation. By exploiting reactivity that is orthogonal to conventional metal-catalysed manifolds, diverse aryl and heteroaryl partners can be rapidly coupled to phenols and naphthols under mild conditions. Following arylation, high-yielding recovery of the Bi(III) precursor allows for its efficient re-use in subsequent reactions. Mechanistic interrogation of each key step of the methodology informs its practical application and provides fundamental insight into the underexploited reactivity of organobismuth compounds.

Chalcogen (S/Se) Ligated Palladium(II) Complexes of Bulky Ligands: Application in O‐Arylation of Phenol

AbstractTwo N‐pyrene based ligands L1 (1‐pyrene‐CH=N(CH2)2‐SPh) and L2 (1‐pyrene‐CH=N(CH2)2‐SePh) with an imine functionality and a chalcogen donor have been synthesized and characterized using 1H as well as 13C NMR spectral techniques. Palladium(II) complexes (1; PdCl2−ĸ2−L1 and 2; PdCl2−ĸ2−L2) of L1 and L2 have been prepared, isolated and characterized using NMR and single crystal X‐ray diffraction studies. The geometry around Pd is nearly square planar in these complexes and ligands are coordinated to the metal centre in a bidentate (S/Se, N) mode. The molecular complexes 1 and 2 have been explored as potential catalysts in O−arylation reaction between substituted aryl halides and phenol. Both the complexes showed excellent efficiency towards this coupling and a TON of 990 (maximum TOF 310) has been achieved using 0.1 mol% of catalyst 2. The effect of the nature of chalcogen donor atom (S/Se) on catalytic efficiency of the complexes has been observed as selenium congener was more efficient than sulphur counterpart.

Magnetically recyclable nano copper/chitosan in O‐arylation of phenols with aryl halides

Interaction of chitosan (CS) with Fe3O4, followed by embedding Cu nanoparticles (NPs) on the magnetic surface through adsorption of Cu2+, and its reduction to Cuo via NaBH4, offers a reusable efficient catalyst (Fe3O4/CS‐Cu NPs) that is employed in cross‐coupling reactions of aryl halides with phenols, which affords the corresponding diaryl ethers, with good to excellent yields. The catalyst is completely recoverable from the reaction mixture by using an external magnet. It can be reused four times, without significant loss in its catalytic activity.

Reactions of quinones with some aryl phenols and synthesis of new quinone derivatives

In the present study, the reactions of p-chloranil (1a) and 2,3-dichloro-1,4-naphthoquinone (DCNQ) (1b) with some aryl phenols were investigated. The structures of all compounds were characterized using spectroscopic methods (FT-IR, 1H NMR, 13C NMR, and MS) and microanalysis. The electrochemical behaviors of some benzoquinone and naphthoquinone derivatives have also been investigated in unbuffered aprotic solutions.

Nucleophilic construction of sulfate bonds: simplified access to polysulfates and polysulfonates

Polysulfates and polysulfonates were prepared in a simplified process through the reaction between aryl phenols and aryl fluorosulfates.

Optimization of a microwave-assisted extraction procedure for the determination of selected alkyl, aryl, and halogenated phenols in sewage sludge and biosolids

A microwave-assisted extraction method for the determination of 15 alkyl, aryl, and halogenated phenols in sewage sludge and biosolids samples was developed and optimized. The effects of solvent, temperature, time, moisture content, acid, and number of extractions on the recovery of phenols were evaluated. Results indicated that extraction solvent had the greatest impact on the recovery of all phenols while pH had the largest effect on recovery of hexachlorophene and pentachlorophenol. Wet sludge samples were extracted with acetone-hexane mixture in the presence of glacial acetic acid. The extract was evaporated, acetylated by acetic anhydride and cleaned up by silica gel. For dry sludge samples, an optional procedure for the simultaneous extraction and acetylation of phenols was also proposed. Triclosan (TCS) and the alkyl and aryl phenols in sludge extracts were analyzed by gas chromatography-mass spectrometry (GC-MS) in electron-impact mode while polyhalogenated phenols were analyzed by GC-MS in negative ion chemical ionization mode. Method detection limits were ca. 200 ng/g for nonylphenol, <25 ng/g for TCS and other alkyl and aryl phenols, and <5 ng/g for other halogenated phenols. This method has been applied to the determination of phenolic compounds in over 150 sludge and biosolids samples since 2009.

Molecular composition of fossil charcoal and relationship with incomplete combustion of wood

Upper Triassic charcoal extracts were studied using gas chromatography–mass spectrometry (GC–MS) to recognize their molecular composition. Extractable compounds were divided into: (i) biomarkers, i.e. diagenetically changed primary wood components and (ii) products of combustion. Major compounds in the first group were: 1,2,5-trimethylnaphthalene and 1,2,5,6-tetramethylnaphthalene, cadalene, dehydroabietane, simonellite and retene. All of these are derived from resins. Moreover, propyl phenols, butyl acetophenones and pentyl acetophenones, as products of lignin breakdown, as well as fatty acids with a predominance of palmitic acid, typical constituents of wood, were also detected. Polycyclic aromatic hydrocarbons (PAHs), as well as ketones and aryl phenols, considered as high temperature combustion products, occurred at relatively low concentration in the samples due to their enhanced solubility in gelified, non-charred wood fragments, and vaporization of the major part of the burn products. Despite the low PAH concentrations, their distribution, with a significant contribution from typical pyrolytic compounds such as anthracene, 4H-cyclopenta[def]phenanthrene, benz[a]anthracene and benzo[a]pyrene was typical for rapid combustion. We propose to estimate paleo-wildfire temperature based on the PAH concentrations in the paleo-charcoal samples. The presence of thermally less stable organic compounds and low PAH abundances indicates a temperature < 400°C. High PAH amounts seem to be characteristic for charring between 400 and 500°C. Above these temperatures PAH concentrations again decrease, but less stable compounds are absent.