Oxidative Coupling Of Phenols Research Articles

Synthesis of Parvistemin A via Biomimetic Oxidative Dimerization

The first synthesis of the naturally occurring benzoquinone dimer parvistemin A is reported. The key step is the late stage iron(III) mediated dimerization of a 1,2,4-trihydroxyarene to give the natural product in good yield, a phenol oxidative coupling that is believed to be biomimetic. The route proceeds in seven steps from an inexpensive commercially available acetophenone in 14% overall yield.

Decontamination of Water Polluted with Phenol using Raphanus sativus Root

Plant materials have been found useful in decontamination of water polluted with phenolic compounds. The detoxification effect is due to peroxidases contained in plant tissue. Enzyme mediated oxidative coupling of phenol is followed by precipitation of the formed polymer and its removal from the aqueous phase. A synthetic wastewater buffered at pH = 7.4 containing 0.9 mM phenol was treated in this research with cut Raphanus sativus root and its juice. Cut Raphanus or Raphanus juice were added separately as enzyme source to phenol solution in buffer and in tap water in two series of experiments. The reaction was initiated by the addition of hydrogen peroxide. After three hours stirring the phenol content of the mixtures was determined. More than 90% of phenol was removed in both cases.

3,3′-Bis(arylbenzofurans) via a Gold-Catalyzed Domino Process

A new heterogeneous gold-catalyzed system for the domino cyclization oxidative coupling of 2-alkynyl phenols for the formation of 3,3′-bisbenzofurans was developed. The substrate and the catalyst scope as well as the reaction conditions were investigated and optimized. This method provides access to this novel structural theme in two steps starting from commercially available chemicals. The molecular structure of the 3,3′-bisbenzofurans was confirmed by single-crystal X-ray analysis.

ChemInform Abstract: Novel Anodic Concepts for the Selective Phenol Coupling Reaction

AbstractReview: 66 refs.

ChemInform Abstract: Ruthenium Dioxide in Fluoro Acid Medium. Part 2. Application to the Formation of Steganes Skeleton by Oxidative Phenolic Coupling.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Novel Oxidative Phenol-Coupling Reaction with Phosphomolybdic Acid on Silica Gel Support: Regioselective Biomimetic Synthesis of Dimeric Phenanthrene Derivatives

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Effects of Transmetalation on the Mechanisms of Copper-Catalyzed Phenolic Oxidative Coupling Reactions.

The mechanism of initiation of phenolic oxidative coupling by the tetranuclear copper(I) complex [pyCuCl]4 is affected by transmetalation. [pyCuCl]4 is stoichiometrically transmetalated by equimolar (M(NS)2 reagents (M is Co, Ni, Cu or Zn) at room temperature in nitrobenzene under N2 to give equimolar solutions of air-sensitive complexes py3Cu3M(NS)Cl4 (IIa-d, respectively) and py and 1 mol of insoluble Cu(NS)(s). The corresponding reaction with equimolar Co(NS)3 gives equimolar solutions of py3Cu3Co(NS)2Cl4 (III) and py and 1 mol of Cu(NS)(s). Here, py is pyridine and NS is monoanionic S-methyl isopropylidenehydrazinecarbodithioate. Second- order reduction of O2 by [pyCuCl]4 gives the tetranuclear oxocopper(II) complex (μ-4-O)py4Cu4Cl4O (Ib). Reduction of O2 by IIc in the presence of equimolar py gives Ib and the disulfide co-product N2S2. The corresponding reductions of O2 by IIa, IIb, IId and III give products py3CuMCl4O2 (IVa, IVb, IVd and IVa, respectively) and N2S2. Insertion of O2 through the Cl4 cores of the reductants is the rate-determining step in each system. However, different product core structures are indicated by different spectral sensitivity to oxidation co-product N2S2 and by different rate laws for their oxidation of 2,6-dimethylphenol (DMPOH) to the corresponding diphenoquinone. These core structures apparently contain either a weakly basic CuOM unit (in IVa and IVb) or a strongly basic CuvO unit (in Ib and IVd). As a result, the rates of oxidation of DMPOH by Ib and IVd are independent of [DMPOH]. Opening of the CuOM unit to give a weakly basic site MvO is proposed to explain induction periods in the IVa, IVb/DMPOH systems, which then proceed at rates which are proportional to [DMPOH]. The origin of different py3, 4Cu3MCl4O2 product core structures is discussed.

ChemInform Abstract: Coupling of Anthrone by Mercury(II) Salts.

Its use as a phenol coupling reagent, however, has not been attempted much . Recently we have reported the coupling of 2,7-dihydroxynaphthalene using mercuric oxide2. Another report appeared in the literature that utilized Hg (II) salts for phenol coupling reaction. The mercuration, however, is more common process occurring in this type of reactions leading to organomercurals4.5. All these facts prompted us to undertake the reaction of anthrone (1) with common Hg (II) salts such as HgCI2 and Hg(OAch under different conditions. The isolation of a host of naturally occurring phenolic bianthronyls6 of important physiological properties and their probable biogenesis through oxidative phenol coupling of the respective monomers created interest amongst us in studying the possible coupling of anthrone leading to bianthronyls using Hg (II) salts. Earlier literature says that mercuric halide would insert to acidic carbons readily, a base helps, and thermal activation would lead to dimerization. For instance, the substrate dibenzyl ketone would dimerize to 1,4-dioxo-2,3,5,6tetrapheny lcyclohexane 7 . Acidity wise, anthrone is also activated and therefore has the chance to dimerize readily. It is interest ing to note that 1, when ICfluxed for nearly 3 hr with Hg(OAc)2 either in glacial acetic acid or in ethanol, afforded a single isolable product establi shed as bianthronyl 2 with >70% yields. The same product in >60% yield could also be obtained

ChemInform Abstract: Phenolic Oxidative Coupling in the Biomimetic Synthesis of Heterocyclic Lignans, Neolignans and Related Compounds

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Novel anodic concepts for the selective phenol coupling reaction

The oxidative phenol coupling reaction of phenols with simple methyl substituents can be difficult due to several by-products. Such a challenging substrate is 2,4-dimethyl-phenol. We studied the electrochemical access to the ortho-coupled dehydrodimer. Anodic treatment in a basic electrolyte supports the formation of a molecular tricyclic architecture called Pummerer’s ketone. Employing a two-step sequence involving anodic conversion of 2,4-dimethylphenol to a preliminary substrate and different workup protocols yield exclusively and diastereoselectively polycyclic architectures. The selective ortho-coupling reaction was achieved by two strategies: A tetraphenoxy borate can be used as template substrate which can be easily made in large scale. Due to the ionic nature of the borate, no supporting electrolyte is required. This methodology can be applied to several related phenolic substrates. The second route is described by the direct conversion of 2,4-dimethylphenol on boron-doped diamond anodes. Surprisingly, the electrochemical transformation does not destruct or mineralize the substrate. Fluorinated additives allow the conversion of a broad scope of substrates.

Thallium(III) in Organic Synthesis

This review article discusses the literature regarding thallium(III)compounds in synthetic organic chemistry published in the last decade,including several applications in the total synthesis of naturalproducts. The reactions that received the most attention in thisperiod were: i) the oxidative rearrangement of chalcones; ii) thering contraction of cyclic alkenes; iii) the oxidation of homoallylicalcohols; iv) aromatic thallations; and v) oxidative couplings,including with phenols. 1 Introduction 2 Non-Oxidative Reactions 3 Oxidative Reactions 3.1 Oxidations with Rearrangement 3.1.1 Ketones 3.1.1.1 Alkyl Aryl Ketones 3.1.1.2 Cyclic Ketones 3.1.1.3 Flavanones 3.1.1.4 Chalcones 3.1.2 Alkenes 3.1.3 Ring Opening of Cyclopropanes 3.2 Oxidations without Rearrangement 3.2.1 Cyclization Reactions 3.2.1.1 Alkenols 3.2.1.2 Carboxylic Acids 3.2.2 α-Oxidation of Ketones 3.2.3 Aromatic Thallation 3.2.4 Oxidative Coupling 3.2.4.1 Phenolic Oxidative Coupling 3.2.4.2 Non-Phenolic Oxidative Coupling 3.2.5 Oxidation of Phenols 3.2.6 Oxidation of Nitrogen Compounds 3.2.7 Disulfide Bond Formation 3.2.8 Deprotection of Thioketals 4 Miscellaneous 5 Conclusions

New method for the study of Amaryllidaceae alkaloid biosynthesis using biotransformation of deuterium-labeled precursor in tissue cultures.

Biotransformation of deuterated-4'-O-methylnorbelladine into alkaloids galanthamine and lycorine in tissue cultures of Leucojum aestivum was demonstrated using HPLC coupled to mass spectrometry. GC-MS screening was also carried to investigate other native and deuterated alkaloids. A total of six labeled alkaloids were identified indicating that 4'-O-methyl-d(3)-norbelladine is incorporated into three different groups of Amaryllidaceae alkaloids that are biosynthesized by three modes of intramolecular oxidative phenol coupling.

Monoclinic CuO nanoflowers on resin support: recyclable catalyst to obtain perylene compound

Monoclinic CuO crystallite in grams has been obtained from resin bound Cu(II)-1,10-phenanthroline complex, R(-)[Cu(1,10-phen)(2)](2+) that becomes a recyclable catalyst for oxidative phenol coupling (OPC) reaction. Thus an exclusively intuitive blue fluorescing perylene derivative is derived from colorless 2,7-dihydroxynaphthalene (2,7-DHN) in high yield.

An Enantiocomplementary Dirigent Protein for the Enantioselective Laccase‐Catalyzed Oxidative Coupling of Phenols

An Enantiocomplementary Dirigent Protein for the Enantioselective Laccase‐Catalyzed Oxidative Coupling of Phenols

A peroxynitrite complex of copper: formation from a copper-nitrosyl complex, transformation to nitrite and exogenous phenol oxidative coupling or nitration.

Reaction of nitrogen monoxide with a copper(I) complex possessing a tridentate alkylamine ligand gives a Cu(I)-(*NO) adduct, which when exposed to dioxygen generates a peroxynitrite (O=NOO(-))-Cu(II) species. This undergoes thermal transformation to produce a copper(II) nitrito (NO(2) (-)) complex and 0.5 mol equiv O(2). In the presence of a substituted phenol, the peroxynitrite complex effects oxidative coupling, whereas addition of chloride ion to dissociate the peroxynitrite moiety instead leads to phenol ortho nitration. Discussions include the structures (including electronic description) of the copper-nitrosyl and copper-peroxynitrite complexes and the formation of the latter, based on density functional theory calculations and accompanying spectroscopic data.

Comparison of soybean peroxidase with laccase in the removal of phenol from synthetic and refinery wastewater samples

AbstractBACKGROUND: Several studies have demonstrated the feasibility of treating aqueous phenols and aromatic amines with oxidoreductases in synthetic wastewater samples. However, little work has been done on the effectiveness of enzymatic treatment on real wastewater. Here a comparison was made of the oxidative coupling of phenol catalyzed by laccase or soybean peroxidase (SBP) using synthetic and refinery wastewaters.RESULTS: Optimization of pH, enzyme concentration, effect of polyethylene glycol (PEG) addition, and reducing anions were examined for a 3 h reaction time. Laccase had an optimum pH of 5.6–6.0, while SBP had a broad optimum from 6.0 to 8.0. In synthetic samples in tap water to achieve ≥ 95% removal of 1.0 mmol L−1 phenol in 3 h required 0.12 and 1.5 U mL−1 of catalytic activity of laccase and SBP, respectively. In refinery samples comparable removals required 1.2‐ to 1.8‐fold more enzyme than in synthetic tap water samples. Added PEG allowed for a small reduction in the SBP concentration for synthetic wastewater but was ineffective with either enzyme in treating refinery samples. Reducing ions increased the demand for oxidant but, with the exception of cyanide, phenol removal still occurred.CONCLUSION: Both laccase and SBP were effective in removing phenol from aqueous refinery samples, albeit at slightly higher concentrations than required for the corresponding synthetic samples. Copyright © 2008 Society of Chemical Industry

First Total Synthesis of (±)-Powelline

The first total synthesis of (±)-powelline is reported in 10% overall yield over eight steps using an intramolecular oxidative phenolic coupling reaction as the key reaction.

Oxidative coupling of by-product coke phenols as a way of their utilization as thermal polymerization coinhibitors in styrene distillation

A procedure was suggested for chemical modification of by-product coke phenols for their use as polymerization inhibitors in petrochemical production of vinyl monomers. The optimal ratios and amounts of components of the inhibiting formulation, Mannich base and modified by-product coke phenols, in heat treatment of styrene were determined.

Platinum nanoparticle catalysed coupling of phenol derivatives with 4-aminoantipyrine in aqueous medium

The oxidative coupling of phenols with 4-aminoantipyrine (AmNH2) has been studied by UV–visible spectroscopy using platinum nanoparticles as catalyst. The rate of antipyrilquinoneimine dye formation depends on the nature of substrates, temperature, pH, and the use of microheterogeneous media such as sodium dodecylsulphate (SDS), cetyl trimethylammonium bromide (CTAB) and Triton X-100 (TX-100). The reactivity trend observed for differently substituted phenols follows the order: 3,5-dimethylphenol > phenol > o-chlorophenol > o-nitrophenol. The rate of dye formation is greater at acid pH than at basic pH and the optimum pH is 5.4. A reaction pathway is proposed, involving the activation of o-chlorophenol with AmNH2 by metal nanoparticles and concomitant reactions of free radicals. Transmission electron microscopy results show that the particle size is 20 nm for the platinum nanoparticles involved in catalysis.

Synthesis of Superparamagnetic β-MnO2 Organosol: a Photocatalyst for the Oxidative Phenol Coupling Reaction

Superparamagnetic monodispersed spherical beta-MnO 2 nanoparticles of approximately 10 nm size with a band gap of 2.52 eV have been synthesized in toluene and support the oxidative phenol coupling reaction as a photocatalyst.