Oxidative Coupling Of Phenols Research Articles

ChemInform Abstract: Synthesis of Condensed Tannins. Part 19. Phenol Oxidative Coupling of (+)‐Catechin and (+)‐Mesquitol. Conformation of Bis‐(+)‐Catechins.

AbstractPhenol oxidative coupling of (+)‐catechin (I) generates low yields of the ether‐ and atropisomeric carbon‐linked bis catechins (II)‐(VI).

Beiträge zur Chemie der Pyrrolpigmente, 76. Mitt.: Die Synthese von symmetrisch substituierten 2,2′-Bipyrrolen durch oxidative Kupplung

A method for the synthesis of symmetrically substituted 2,2′-bipyrroles using the oxidation of α-unsubstituted pyrrole derivatives—in analogy to the oxidative coupling of phenols—is presented together with four examples. The mechanistic implications are discussed.

Cerium(IV) induced hydroxylation of c-alkylated hydrocarbons and phenols

Hydroxylation of C-alkylated phenols has been achieved by employing cerium (IV) ammonium nitrate and hydrogen peroxide in acetic acid medium. The yield of hydroxylation products increases markedly when 3 × 10 -3 M solution of sodium dodecyl sulphate is added to the oxidation system. The plausible mechanism of the reaction seems to involve free radical intermediates and is influenced by hydrophobic environment. The findings are also of significance from the view point of oxidative coupling of phenols.

Oxidative Coupling of Lignans. II. Non-Phenolic Coupling of Diarylbutane Lignans Related to Matairesinol Dimethyl Ether

The non- phenolic oxidative coupling of some diarylbutane lignans related to matairesinol dimethyl ether (1) has been investigated. Coupling with a thallium(III) oxidant, prepared in situ from thallium(III) oxide and trifluoroacetic acid, converts these lignans efficiently into either dibenzocyclooctadiene or aryltetralin lignans. The dibenzocyclooctadiene lignan (5) prepared from oxidative coupling of matairesinol dimethyl ether has been converted into compound (26) which has significant in vitro antileukaemic activity. The structure of the isostegane (27) formed by oxidative coupling of dimethylbutane (14) has been confirmed by X-ray crystallography.

Oligomeric isoflavonoids. Part 2. Structure and synthesis of xanthocercin A and B, the first isoflavono-lignoids

The structures of xanthocercin A and B, the first Isoflavono-lignoids, have been established as 2,3-trans-3-(4-hydroxy-3,5-dimethoxyphenyl)-8-(3-hydroxy-4-methoxyphenyl)-2-hydroxymethyl-2,3-dihydro-7H-1,4-dioxino[2,3-h]chromen-7-one (1) and 2,3-trans-8-(3-hydroxy-4-methoxyphenyl)-3-(4-hydroxy-3-methoxyphenyl)-2-hydroxymethyl-2,3-dihydro-7H-1,4-dioxino[2,3-h]chromen-7-one (3) respectively by spectroscopic methods. These structures have been confirmed by synthesis via phenol oxidative coupling of the appropriate 7,8-dihydroxyisoflavone and respectively sinapyl and coniferyl alcohol. The natural occurrence of xanthocercin A and B as single regioisomers and their regiospecific formation during synthesis presumably originate from marked differences in susceptibility to oxidation of the hydroxy functions in their ‘catechol precursors’.

ChemInform Abstract: Synthetic Approaches to Cularines. Part 1. Phenolic Oxidative Coupling.

AbstractThe N‐benzoyldihydroisoquinolinenitrile (II) is coupled with the chloromethyldialkoxybenzenes (IV) under phase‐transfer conditions, yielding the compounds (V).

Structures of the pyrazolones formed by oxidative coupling of phenols with 4-aminoantipyrine

The structures of reaction products between 4-amino-2,3-dimethyl-1-phenyl-3-pyrazolin-5-one and o-cresol, p-cresol, and p-ethylphenol are reported. The reaction of the former compound with phenols is used to estimate the concentration of phenol in potable water supplies. The reaction products are 2,3-dimethyl-4-[4-oxo-2,5-cyclohexadien-1-ylidene)amino]-1-phenyl-3-pyrazolin-5-one (monoclinic, P21/c, red, Z = 4, a = 7.092(1), b = 26.616(2), c = 8.644(2) Å, β = 79.17(3)°, 1432 reflections, R = 0.083, Rw = 0.040), 1,9a-dihydro-1,6,9a-trimethyl-2-phenylpyrazolo[3,4-b][1,4]benzoxazin-3(2H)-one (orthorhombic, Pbca, yellow, Z = 8, a = 18.943(3), b = 12.749(5), c = 13.223(2) Å, 2122 reflections, R = 0.067, Rw = 0.038), and 6-ethyl-1,9a-dihydro-1,9a-dimethyl-2-phenylpyrazolo[3,4-b|[1,4]benzoxazin-3(2H)-one (orthorhombic, Pbca, yellow, a = 18.895(11), b = 12.737(5), c = 14.041(6) Å, Z = 8, 1126 reflections, R = 0.068, Rw = 0.061), respectively. The latter two compounds rearrange to form 1,2,4,10-tetrahydro-1,6-dimethyl-2-phenyl-3H-pyrazolo[3,4-c][1,5]benzoxazepin-3-one (monoclinic, P21/c, white, Z = 8, a = 15.072(4), b = 14.491(4), c = 15.505(3) Å, β = 111.15(1)°, 3416 reflections, R = 0.101, Rw = 0.046) and 6-ethyl-1,2,4,10-tetrahydro-1-methyl-2-phenyl-3H-pyrazolo[3,4-c][1,5]benzoxazepin-3-one (monoclinic, C2/c, white, Z = 8, a = 33.768(3), b = 6.678(1), c = 15.836(2) Å, β = 115.41(1), 2805 reflections, R = 0.076, Rw = 0.043), respectively. The rearrangement is consistent with the observation that the pyrazolone rings of benzoxazinones are strained, as manifested by enlarged perimeters.

Synthetic approaches to cularines. I. Phenolic oxidative coupling

AbstractFerricyanide‐promoted biogenetic‐type phenolic oxidative coupling of an 8,3′‐dihydroxytetrahydrobenzyl‐isoquinoline 19a afforded the isomeric phenolic cularines 5 and 21. Vanadium oxytrifluoride oxidation of the N‐borane complex of 19a afforded, regioselectively, the para‐coupled product 21. Moreover, when this reagent was used on the monophenolic tetrahydrobenzylisoquinoline 19b protected as its N‐borane complex, cularine 1 was regioselectively obtained in good yield. Other structural modifications and reagents were not successful.

Purification and properties of dihydrogeodin oxidase from Aspergillus terreus.

The last step of (+)-geodin biosynthesis is a phenol oxidative coupling, which is one of the most important reactions in biosynthesis of natural products. The enzyme named dihydrogeodin oxidase catalyzes the regio- and stereospecific phenol oxidative coupling reaction to form (+)-geodin from dihydrogeodin. The enzyme was purified from the cell-free extract of Aspergillus terreus, a (+)-geodin producer, by ammonium sulfate fractionation, acid treatment, and column chromatographies on DEAE-cellulose, Hydroxyapatite, chromatofocusing, and Toyopearl HW-55S. The purified enzyme was homogeneous as judged by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The molecular weight of the enzyme was estimated to be 153,000 by gel filtration on a Toyopearl HW-55S column and 76,000 by SDS-polyacrylamide gel electrophoresis, indicating that the enzyme is a dimer. The purified enzyme showed an intense blue color and had absorption maxima at 280 and 600 nm, which suggested it to be a blue copper protein. The copper content was found to be 8 atoms per subunit by atomic absorption analysis and no significant amount of other metals was detected by ICP emission spectrometry. The electron paramagnetic resonance spectrum showed the presence of type 1 and type 2 copper atoms in the enzyme molecule. Sodium azide and ethylxanthate inhibited the enzyme activity, but potassium cyanide and diethyldithiocarbamate, both known as potent copper enzyme inhibitors, were not inhibitory.

Synthesis of condensed tannins. Part 19. Phenol oxidative coupling of (+)-catechin and (+)-mesquitol. Conformation of bis-(+)-catechins

Phenol oxidative coupling of (2R,3S)-2,3-trans-3′,4′,5,7-tetrahydroxyflavan-3-ol[(+)-catechin] generates low yields of ether-{[3′O,8]- and [4′O,8]-} and atropisomeric carbon-linked {[2′,8]-,[2′,6]-, and [6′,8]-} bis-(+)-catechins. The isomeric structures were differentiated by nuclear Overhauser effect difference spectroscopy. Extension of condensation of (+)-catechin with (2R,3S)-2,3-trans-3′,4′,7,8-tetrahydroxyflavan-3-ol[(+)-mesquitol] readily affords the four atropisomeric [5,6:5,8]-bis-[(+)-mesquitol]-(+)-catechins previously encountered in the heartwood of Prosopis glandulosa(‘Mesquite’).

ChemInform Abstract: Synthesis of Nitrohydroxyxanthones and Oxidative Coupling of Phenols Using Cerium(IV) Ammonium Nitrate.

Chemischer InformationsdienstVolume 17, Issue 20 Preparative Organic Chemistry ChemInform Abstract: Synthesis of Nitrohydroxyxanthones and Oxidative Coupling of Phenols Using Cerium(IV) Ammonium Nitrate. K. CHAUDHURI, K. CHAUDHURISearch for more papers by this authorH. M. CHAWLA, H. M. CHAWLASearch for more papers by this author K. CHAUDHURI, K. CHAUDHURISearch for more papers by this authorH. M. CHAWLA, H. M. CHAWLASearch for more papers by this author First published: May 20, 1986 https://doi.org/10.1002/chin.198620128Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume17, Issue20May 20, 1986 RelatedInformation

The biosynthesis of cularine

The incorporation of radioactive crassifoline into cularine proved crassifoline to be the precursor of the cularine alkaloids. Phenolic oxidative coupling is presented as the biogenetic mechanism.

New Catalytic Systems for the Oxidative Polymerization of 2,6-DimethyIphenol

Abstract A new principle for improving the catalytic activity of the classical complexes CuCl2-aliphatic amines used for the oxidative coupling of 2,6-dimethylphenol (DMP) is presented. It is based on the “trans” effect, typical of the substitution reactions of ligands in the square planar complexes of platinum(II). Thus, by replacing a Cl− anion with a strong “trans” effect-giving ligand such as NO2 −, CN−, RS−, , a significant increase in the rate of oxidative coupling of 2,6-DMP is observed. It was quantitatively estimated by measuring the oxygen absorption rate. The highest reaction rates are given by complexes having CUS bonds (mercap-tides, thiophenolates, thiosulfates). These bonds, which probably have a high oxygen affinity, are typical for copper-containing enzymes (laccase, tyrosinase, ascorbic acid oxidase), redox enzymes that catalyze the oxidative coupling of some natural phenols very efficiently.

The evaluation of a biogenetically based approach to the synthesis of octahydro-1h-benzofuro[3,2-e]isoquinolines

A potential synthetic route to octahydro-1 H -benzofuro [3,2-e]isoquinoline derivatives by intermolecular oxidative phenolic coupling has been studied. A variety of successful coupling reactions have been effected between 2-naphthol or 4-t-butylphenol and p-cresol, 2-(p-hydroxyphenyl)ethanol, 3,4-dimethylphenol, 5-indanol and 6-hydroxytetralin, but 2-acetyl-7-hydroxytetrahydroisoquinoline failed to participate in such reactions.

ChemInform Abstract: TRANSMETALATION REACTIONS OF TETRANUCLEAR COPPER(II) COMPLEXES. 2. STOICHIOMETRY AND PRODUCTS OF REACTION OF ((DENC)CUCL)4O2, ((DENC)CUCL)4(CO3)2, ((DENC)CUCL)4CL4, AND (DENC)4CU4CL6O (DENC = N,N‐DIETHYLNICOTINAMIDE) WITH NI(NS)2 , THE KINETICS OF PRODUCT ISOMERIZATION IN APROTIC SOLVENTS, AND INHIBITION OF COPPER‐CATALYZED PHENOLIC OXIDATIVE COUPLING BY DIOXYGEN THROUGH TRANSMETALATION

Chemischer InformationsdienstVolume 15, Issue 46 Organoelement Compounds ChemInform Abstract: TRANSMETALATION REACTIONS OF TETRANUCLEAR COPPER(II) COMPLEXES. 2. STOICHIOMETRY AND PRODUCTS OF REACTION OF ((DENC)CUCL)4O2, ((DENC)CUCL)4(CO3)2, ((DENC)CUCL)4CL4, AND (DENC)4CU4CL6O (DENC = N,N-DIETHYLNICOTINAMIDE) WITH NI(NS)2 , THE KINETICS OF PRODUCT ISOMERIZATION IN APROTIC SOLVENTS, AND INHIBITION OF COPPER-CATALYZED PHENOLIC OXIDATIVE COUPLING BY DIOXYGEN THROUGH TRANSMETALATION A. EL-TOUKHY, A. EL-TOUKHYSearch for more papers by this authorG.-Z. CAI, G.-Z. CAISearch for more papers by this authorG. DAVIES, G. DAVIESSearch for more papers by this authorT. R. GILBERT, T. R. GILBERTSearch for more papers by this authorK. D. ONAN, K. D. ONANSearch for more papers by this authorM. VEIDIS, M. VEIDISSearch for more papers by this author A. EL-TOUKHY, A. EL-TOUKHYSearch for more papers by this authorG.-Z. CAI, G.-Z. CAISearch for more papers by this authorG. DAVIES, G. DAVIESSearch for more papers by this authorT. R. GILBERT, T. R. GILBERTSearch for more papers by this authorK. D. ONAN, K. D. ONANSearch for more papers by this authorM. VEIDIS, M. VEIDISSearch for more papers by this author First published: November 13, 1984 https://doi.org/10.1002/chin.198446307AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume15, Issue46November 13, 1984 RelatedInformation

Light scattering studies of the stability of liquid fuels

Storage stabilities of upgraded coal-derived liquids (H-coal and SRC-II), JP-5 jet fuels derived from petroleum and oil shale, and a petroleum-derived diesel fuel were compared using laser light scattering measurements. The most severely hydrotreated coal-derived liquids have stability characteristics comparable to the jet fuels derived from petroleum and oil shale. Fuel degradation was monitored in the presence of added specific heteroatomic compounds. Very pronounced enhancement of light scattering intensity has been observed for coal-derived liquids containing the following additives: 1. phenol + pyridine + Cu; 2. 2,6-di-tertbutylphenol (DTBP) + pyridine + Cu; 3. phenol + dimethylquinoline, (DMQ) + (Cu; and 4. 2,5-dimethylpyrrole (DMP) + thiophenol. Previous studies have shown that phenolic oxidative coupling is an important reaction responsible for the ageing of coal-derived liquids and this observation is confirmed here. Pyridine and DMQ complexed with Cu are shown to be effective catalysts for oxidative coupling. DMP by itself is deleterious to fuel stability, in that it promotes sediment formation and light scattering. During accelerated ageing of upgraded H-coal in the presence of DMP a sediment formed with empirical formula C7H8NO1.3, which was further characterized by solid-state C 13 n.m.r. and X-ray photoelectron spectroscopy.

Transmetalation reactions of tetranuclear copper(II) complexes. 2. Stoichiometry and products of reaction of [(DENC)CuCl]4O2, [(DENC)CuCl]4(CO3)2, [(DENC)CuCl]4Cl4, and (DENC)4Cu4Cl6O (DENC = N,N-diethylnicotinamide) with Ni(NS)2 , the kinetics of product isomerization in aprotic solvents, and inhibition of copper-catalyzed phenolic oxidative coupling by dioxygen through transmetalation

Transmetalation reactions of tetranuclear copper(II) complexes. 2. Stoichiometry and products of reaction of [(DENC)CuCl]4O2, [(DENC)CuCl]4(CO3)2, [(DENC)CuCl]4Cl4, and (DENC)4Cu4Cl6O (DENC = N,N-diethylnicotinamide) with Ni(NS)2 , the kinetics of product isomerization in aprotic solvents, and inhibition of copper-catalyzed phenolic oxidative coupling by dioxygen through transmetalation

Oxidative Coupling of Phenols and Anilines by Peroxidase: Structure‐Activity Relationships

AbstractWe investigated the relationship between molecular structure and reactivity for the peroxidase mediated coupling of substituted anilines and phenols. We undertook this study to gain a better understanding of the oxidative coupling processes operative in soil involving peroxidase enzymes. The relative reaction rates of the various substituted aniline and phenol compounds (electron donors) were determined by measuring electron donor disappearance using high pressure liquid chromatography. The effects of structure on reactivity were treated quantitatively by use of the Hammett equation. We found a good correlation between electron donor rate constants and their respective Hammett substituent σ+ constants which indicated the formation of a positively charged transition state as the rate controlling step. The ρ values obtained from these correlations were negative, demonstrating that reactivity was increased by the presence of electron‐donating substituents on the aromatic ring which act to stabilize the positively charged transition state. These results suggested that the reaction rates depended on electron density at the reaction center (−NH2 or ‐OH) in a predictable manner.

Oxidative Coupling of Phenols and Anilines by Peroxidase: Structure‐Activity Relationships

Oxidative Coupling of Phenols and Anilines by Peroxidase: Structure‐Activity Relationships

Lignin-degrading enzyme from Phanerochaete chrysosporium : Purification, characterization, and catalytic properties of a unique H 2 O 2 -requiring oxygenase

An extracellular lignin-degrading enzyme from the basidiomycete Phanerochaete chrysosporium Burdsall was purified to homogeneity by ion-exchange chromatography. The 42,000-dalton ligninase contains one protoheme IX per molecule. It catalyzes, nonstereospecifically, several oxidations in the alkyl side chains of lignin-related compounds: C(alpha)-C(beta) cleavage in lignin-related compounds of the type aryl-C(alpha)HOH-C(beta)HR-C(gamma)H(2)OH (R = -aryl or -O-aryl), oxidation of benzyl alcohols to aldehydes or ketones, intradiol cleavage in phenylglycol structures, and hydroxylation of benzylic methylene groups. It also catalyzes oxidative coupling of phenols, perhaps explaining the long-recognized association between phenol oxidation and lignin degradation. All reactions require H(2)O(2). The C(alpha)-C(beta) cleavage and methylene hydroxylation reactions involve substrate oxygenation; the oxygen atom is from O(2) and not H(2)O(2). Thus the enzyme is an oxygenase, unique in its requirement for H(2)O(2).