Coupling Of 2-naphthols Research Articles

ChemInform Abstract: Mutual Activation: Suzuki—Miyaura Coupling Through Direct Cleavage of the sp2 C—O Bond of Naphtholate.

AbstractKey step of the direct Suzuki—Miyaura coupling of naphthols with various aryl boroxines is the in situ generation of borates offering a new concept of mutual activation of the coupling partners.

Task-specific ionic liquid catalyzed efficient microwave-assisted synthesis of 12-alkyl or aryl-8,9,10,12-tetrahydrobenzo[a]xanthen-11-ones under solvent-free conditions

The green, mild, and efficient synthesis of 12-alkyl or aryl-8,9,10,12-tetrahydrobenzo[a]xanthen-11-ones has been achieved by a three-component coupling of 2-naphthol, aldehydes, and cyclic1,3-dicarbonyl compounds in the presence of a sulfonic acid functionalized ionic liquid without any solvent under microwave irradiation. The catalyst can be reused at least eight times without any noticeable decrease in catalytic activity.

Chiral Cu(II) salen complexes catalyzed aerobic oxidative biaryl coupling-probing the reaction by EPR

Aerobic oxidative coupling of 2-naphthol to 1,1'-binaphthyl-2,2'-diol has been achieved using chiral/achiral copper salen complexes as catalyst. Moderate enantioselectivity was obtained for the reaction of 2-napthol with a coordinating substituent with a chiral salen complex. Unsubstituted 2-naphthol resulted in racemic 1,1'-binaphthyl-2,2'-diol only with all chiral complexes. Electron paramagnetic resonance spectroscopy has been used to understand the factors influencing the asymmetric induction.

Catalytic activity of choline modified Fe(III) montmorillonite

A series of mixed-cation organoclays, containing both Fe 3+ and choline + cations, were prepared using montmorillonite and tested for catalytic activity in three Fe 3+-mediated reactions: the oxidative coupling of 2-naphthol, coupling of anthrone and a Lewis-acid catalysed indole conjugate addition. Clays with different Fe 3+:choline + ratios were required to achieve maximum catalytic activity in each reaction. For coupling of both 2-naphthol and anthrone, the most effective catalysts, as measured by the turnover frequency (TOF), were mixed Fe 3+/choline + clays of varying ratios, but the catalytic efficiency of Fe 3+ montmorillonite in the conjugate addition of indole with methyl vinyl ketone decreased with the addition of choline +. This result could potentially be explained by the effect of choline + decreasing the accessibility of Lewis acid domains. The results of this study provide proof that it is possible to tune mixed-cation clays with maximum catalytic activity in specific reaction types for specific substrates. Such mixed-cation organoclays offer advantages over traditional clay-based sorbents in environmental remediation applications, as they have the potential to bind organic contaminants selectively, via interaction with surface-exchanged organic cations, and neutralise organic molecules through catalytic exchange cations that are also present on the clay surface.

A Simple and Efficient Oxidative Coupling of Aromatic Nuclei Mediated by Manganese Dioxide

Oxidative intramolecular coupling of the aryl rings of various stilbenes for direct construction of the phenanthrene ring system is promoted efficiently by manganese dioxide―trifluoroacetic acid at room temperature in excellent yields. This approach is also applied to the intermolecular biaryl coupling of 2-naphthols, 2-naphthalenethiol, 2-naphthylamine, a phenol ether and a phenol under very mild conditions. An electron-transfer mechanism is proposed in which manganese dioxide acts as a two-electron oxidant.

ChemInform Abstract: An Efficient One‐Pot Synthesis of Naphthoxazinones by a Three‐Component Coupling of Naphthol, Aldehydes, and Urea Catalyzed by Zinc Triflate.

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Synthesis of Spiro Compounds through Tandem Oxidative Coupling and a Framework Rearrangement Reaction

A highly efficient oxidative coupling of 2-naphthols and a rearrangement tandem reaction to afford unique spiro compounds in the presence of FeCl(3).6H(2)O in up to 88% yield have been developed.

Partial Exchange of Fe(III) Montmorillonite with Hexadecyltrimethylammonium Cation Increases Catalytic Activity for Hydrophobic Substrates

Fe(III) montmorillonite clay that was partially exchanged with hexadecyltrimethylammonium (HDTMA(+)) cations achieved increased catalytic activity for the oxidative coupling of hydrophobic organic substrates. A series of mixed-cation organoclays were produced, where the organic cation content ranged from 6 to 50% relative to the cation-exchange capacity (CEC) of the clay, and were tested for catalytic activity using different Fe(III)-mediated oxidative coupling reactions. Enhanced catalytic activity by Fe(3+)/HDTMA(+) montmorillonite for coupling hydrophobic substrates was observed, with maximum catalytic activity in the oxidative coupling of 2-naphthol observed at 6% HDTMA(+) coverage. However, maximum catalytic activity with a more hydrophobic substrate, anthrone, was achieved with 50% HDTMA(+) coverage, indicating that matching levels of organic modification to substrate hydrophobicity improves catalytic activity. The organization of the organic cations at the clay surfaces proved to be heterogeneous, as determined by scanning transmission X-ray microscopy (STXM) and powder X-ray diffraction. Results from molecular dynamics simulations supported the heterogeneous nature of the catalysts but also pointed toward large regions within the interlayers that may be filled with nonreactive hydrated Fe oxides resulting from the organic cation treatment. The exchangeable Fe content of the organic treated clays, as determined by AAS and ICP measurements, was observed to be higher than expected relative to that of Fe-saturated clay, substantiating this hypothesis. These findings have implications for the development of substrate-specific clay catalysts, where the composition and configuration of exchangeable cations can be matched to a particular substrate or reaction.

Synthesis of C1‐Symmetric BINOLs Employing N‐Heterocyclic Carbene–Copper Complexes

Fucntionalizing BINOL: Bis-NHCCu complexes can be used for the oxidative coupling of 2-naphthols. Product yields are highest when using electron-deficient 2-naphthols. Mixed couplings between electron-rich and electron-poor 2-naphthols can be conducted to give good yields of the mixed products.

An efficient one‐pot synthesis of naphthoxazinones by a three‐component coupling of naphthol, aldehydes, and urea catalyzed by zinc triflate

Abstract magnified imageA simple and efficient method has been developed for the synthesis of 4‐aryl‐3,4‐dihydronaphtho[2,1‐e] [1,3]oxazin‐2‐one and 1‐aryl‐1,2‐dihydronaphtho[1,2‐e][1,3]oxazin‐3‐one derivatives through a one‐pot three‐component coupling of α or β‐naphthol, aromatic aldehydes and urea using a catalytic amount of zinc triflate in refluxing acetonitrile. J. Heterocyclic Chem., (2009).

Gallium(III) chloride-catalyzed three-component coupling of naphthol, alkyne and aldehyde: a novel synthesis of 1,3-disubstituted-3 H-benzo[ f] chromenes

Three-component coupling of naphthol, alkyne and aldehyde has been achieved in the presence of 10 mol % gallium(III) chloride in toluene under reflux conditions to afford the corresponding 1,3-disubstituted-3 H-benzo[ f]chromenes in good yields. This is the first example on the preparation of chromenes from naphthol, alkyne and aldehyde.

Iron-Catalyzed Asymmetric Aerobic Oxidation: Oxidative Coupling of 2-Naphthols

Fe(salan) complexes were found to be efficient catalysts for the asymmetric aerobic oxidative coupling of 2-naphthol derivatives. This reaction can be carried out in air at 60 degrees C with high enantioselectivity up to 97% ee. This is the first report for asymmetric aerobic oxidation using molecular oxygen in air in the absence of additives.

Ferric hydrogensulfate catalyzed aerobic oxidative coupling of 2-naphthols in water or under solvent free conditions

The symmetric oxidative coupling reactions of 2-naphthol derivatives with both ferric hydrogensulfate in water and silica ferric hydrogensulfate in solvent free conditions were carried out. The advantages of this green procedure are: inexpensive catalyst or co-catalyst, reusability of catalyst, organic solvent-free procedures and simple workup.

Development of Dinuclear Vanadium Catalysts for Enantioselective Coupling of 2-Naphthols via a Dual Activation Mechanism

This review describes our recent efforts in the development of chiral dinuclear vanadium complexes which work as dual activation catalysts for oxidative coupling of 2-naphthols. A chiral dinuclear vanadium(IV) complex (R(a),S,S)-1a possessing (S)-tert-leucine moieties at the 3,3'-positions of the (R)-binaphthyl skeleton was developed, and found to promote oxidative coupling of 2-naphthol to afford (S)-1,1'-bi-2-naphthol (BINOL) with 91% ee. To verify the dual activation mechanism, mononuclear vanadium(IV) complex (S)-10 was also prepared. Kinetic analysis revealed that the reaction rate of oxidative coupling of 2-naphthol promoted by (R(a),S,S)-1a is 48.3 times faster than that of (S)-10. In the coupling reaction, the two vanadium metals in the chiral complex activate two molecules of 2-naphthol simultaneously achieving a high reaction rate with high enantiocontrol. Since the dinuclear vanadium(IV) complex was found to be readily oxidized to afford a corresponding vanadium(V) species during preparation in air, a new synthetic procedure using VOCl3 and a convenient one-pot procedure using VOSO4 under O2 have been applied towards dinuclear vanadium(V) complexes (R(a),S,S)-2. The coupling of 2-naphthol was catalyzed by (R(a),S,S)-2 with reaction rates enhanced 2.3 times faster than that of (R(a),S,S)-1a, which is likely a precatalyst. To the best of our knowledge, (R(a),S,S)-1a, 2, and 3 show considerably higher catalytic activity than previously reported vanadium complexes for oxidative coupling of 2-naphthols.

Iron(III) Chloride Catalyzed Oxidative Coupling of Aromatic Nuclei

Easily available and nontoxic FeCl(3) catalyzes intramolecular oxidative coupling for the direct construction of the phenanthrene ring using meta-chloroperbenzoic acid as sole oxidant at room temperature in excellent yields. The mechanistic investigations show that FeCl(3)-catalyzed coupling proceeds through the heterolytic coupling (A(+) + B). The catalytic approach has been applied to intermolecular biaryl coupling of 2-naphthols and phenol ether.

Gas‐Phase Study on the CC Coupling of Naphthol Catalyzed by CuII⋅TMEDA: Evidence for the Key Role of Binuclear Clusters

The mechanism of oxidative coupling of two naphthol molecules to form binaphthol catalyzed by Cu(OH)ClTMEDA (TMEDA=N,N,N',N'-tetramethylethylenediamine) was approached by means of a gas-phase model system. Concise evidence is provided that the coupling reaction proceeds in clusters with two Cu(II) centers, whereby the intermediacy of free naphthoxy radicals in the coupling step is avoided. In the absence of TMEDA, the cluster is bound via a bridging counterion and the coupling reaction is followed by cluster cleavage. The coordination of one or two TMEDA molecules to the reactive complex results in more efficient coupling of naphthol molecules, and moreover, the binuclear cluster is also conserved after the reaction is completed. The effect of TMEDA is twofold: First, it supports clustering of copper and, second, as a ligand bound to a copper center in the reactive complex, it weakens the bond between copper and the naphtholato ligand such that the naphtholato unit is more prone to undergo C--C coupling. Furthermore, a pronounced counterion effect is found that correlates well with condensed-phase data: weakly bridging counterions (e.g., NO3(-)) yield less stable dicopper clusters and the coupling reaction hardly occurs, whereas better bridging counterions (e.g., Cl(-) or Br(-)) provide more stable clusters that make the coupling reaction more efficient.

Dual activation in oxidative coupling of 2-naphthols catalyzed by chiral dinuclear vanadium complexes

An efficient enantioselective oxidative coupling of 2-naphthol derivatives based on a concept of dual activation catalysis is realized. A chiral dinuclear vanadium(IV) complex ( R a, S, S)- 1e possessing ( S)- tert-leucine moieties at the 3,3′-positions of the ( R)-binaphthyl skeleton was developed, which was found to promote the oxidative coupling of 2-naphthol to afford ( S)-BINOL with 91% ee. To verify the dual activation mechanism, mononuclear vanadium(IV) complex ( S)- 8 was also prepared. Kinetic analysis revealed that the reaction rate of oxidative coupling of 2-naphthol promoted by ( R a, S, S)- 1e is 48.3 times faster than that of ( S)- 8. The two vanadium metals in the chiral complex activate two molecules of 2-naphthol simultaneously in an intramolecular manner coupling reaction, achieving a high reaction rate with high enantiocontrol. Reaction mechanisms of the oxidative coupling reaction promoted by either vanadium(IV) or vanadium(V) complexes are also described.

Dinuclear chiral vanadium catalysts for oxidative coupling of 2-naphthols via a dual activation mechanism

This review describes our recent efforts in the development of chiral dinuclear vanadium complexes that work as dual activation catalysts for the oxidative coupling of 2-naphthols. The dinuclear vanadium(iv) complex (R(a),S,S)- was prepared by complexation of VOSO(4) with the Schiff base derived from (R)-3,3'-diformyl-2,2'-dihydroxy-1,1'-binaphthyl () and (S)-tert-leucine. Since the dinuclear vanadium(iv) complex was found to be readily oxidized to afford a corresponding vanadium(v) species during preparation in air, a new synthetic procedure using VOCl(3) has been applied towards dinuclear vanadium(v) complexes (R(a),S,S)- and (R(a),S,S)-. To the best of our knowledge, (R(a),S,S)-, and show considerably higher catalytic activity than previously reported vanadium complexes for the oxidative coupling of 2-naphthols.

Chiral dinuclear vanadium(v) catalysts for oxidative coupling of 2-naphthols

Preparation and structural analysis of chiral dinuclear vanadium(v) catalysts with high catalytic activity for the oxidative coupling of 2-naphthols are described.

Highly Enantioselective Oxidative Couplings of 2-Naphthols Catalyzed by Chiral Bimetallic Oxovanadium Complexes with Either Oxygen or Air as Oxidant

The chiral bimetallic oxovanadium complexes have been designed for the enantioselective oxidative coupling of 2-naphthols bearing various substituents at C6 and/or C7. The chirality transferring from the amino acid to the axis of the biphenyl in oxovanadium complexes 2 was found to occur with the use of UV and CD spectra and DFT calculation. The homo-coupling reaction with oxygen as the oxidant was promoted by 5 mol % of an oxovanadium complex derived from L-isoleucine and achiral biphenol to afford binaphthols in nearly quantitative yields with high enantioselectivities of up to 98% ee. An oxovanadium complex derived from L-isoleucine and H8-binaphthol is highly efficient at catalyzing the air-oxidized coupling of 2-naphthols with excellent enantioselectivities of up to 97% ee. 51V NMR study shows that the oxovanadium complexes have two vanadium(V) species. Kinetic studies, the cross-coupling reaction, and HRMS spectral studies on the reaction have been carried out and illustrate that two vanadium(V) species are both involved in catalysis and that the coupling reaction undergoes a radical-radical mechanism in an intramolecular manner. Quantum mechanical calculations rationalize the importance of the cooperative effects of the axial chirality matching S-amino acids on the stereocontrol of the oxidative coupling reaction. The application of the transformation in the preparation of chiral ligands and conjugated polymers confirms the importance of the current process in organic synthesis.