- ortho-Selective phenol-coupling reaction by anodic treatment on boron-doped diamond electrode using fluorinated alcohols
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A study was conducted to demonstrate ortho-selective phenol-coupling reaction by anodic treatment on boron-doped diamond electrode using fluorinated alcohols. A protocol for the conversion of neat phenol on boron-doped diamond (BDD) electrodes was also developed for the study. Partial conversion of 30% was carried out to prevent electrochemical incineration and to avoid by-products. It was observed that the free path length of oxyl radicals generated on BDD electrodes were found in the nanometer range. Methanol and other simple alcohols were used in the study on the anodic phenol coupling reaction. It was also found that some amount of methanol disappeared from the electrolysis cell despite cooling the electrolyte. Hexafluoroisopopanol with supporting electrolytes produced a powerful electrolyte system for the anodic coupling reaction of phenols.
- Kirste, Axel,Nieger, Martin,Malkowsky, Itamar M.,Stecker, Florian,Fischer, Andreas,Waldvogel, Siegfried R.
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- An efficient and practical direct resolution of racemic 1,1'-bi-2-naphthol to both of its pure enantiomers
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An efficient and practical method to directly resolve racemic 1,1'-bi-2-naphthol, rac-1, into optically pure R and S-1 has been developed by modification of a N-benzylcinchonidium chloride resolution procedure. In a typical experiment, 60 g of rac-1 is resolved to give 22.5 g of R-1 (75%, >99% ee) and 21 g of S-1 (70%, >99% ee). The chiral resolving agent, (8S,9R)-(-)-N-benzylcinchonidinium chloride, 2, is recovered in 80% yield.
- Hu,Vitharana,Pu
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- Visible Light-Promoted C-C Bond Formation from Hydroxyaryls in Water
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An eco-friendly and direct arylation of hydroxyaryls in water using photoinduced reactions with different substrates (1-bromo-2-naphthol, 1-iodo-2-naphthol, N-(2-iodophenyl)acetamide, 5-bromouracil, 2-iodo-N-methylbenzamide, and 2-iodobenzamide) was studied. For example, π-expanded coumarins, compounds with potential optical applications, were synthesized in very high yield, without the use of toxic reagents, in a one-pot reaction. In addition, we demonstrate that the irradiation source (halogen lamp) can be efficiently replaced by an LED without altering the reaction yield.
- Saporito, Dafne,Rodriguez, Sergio A.,Baumgartner, Maria T.
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- Novel horseradish peroxidase catalysed enantioselective oxidation of 2-naphthols to 1,1'-binaphthyl-2,2'-diols
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Enantioselective oxidation of 2-naphthols to 1;1'-binaphthyl-2,2'-diols catalysed by horseradish peroxidase is described.
- Sridhar, Madabhushi,Vadivel, Subramanian K.,Bhalerao, Uday T.
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- Resolution of Racemic 1,1'-Bi-2-naphthol Using (S)-Proline via a Cyclic Borate Ester
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1,1'-Bi-2-naphtholborane generated from racemic 1,1'-bi-2-naphthol and borane dimethyl sulfide complex reacted with (S)-proline in tetrahydrofuran to form a spirocyclic 1,1'-bi-2-naphtholboric proline anhydride. Its two diastereoisomers could be separated efficiently under the experimental conditions, from which enantiomerically pure (R)-(+)- and (S)-(-)-1,1'-bi-2-naphthol were obtained in ca. 80 percent overall yield, respectively. - Keywords: resolution; 1,1'-bi-2-naphthol; (S)-proline; cyclic borate ester.
- Shan, Zixing,Xiong, Ying,Zhao, Dejie
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- Metal-free carbon as a catalyst for oxidative coupling: Solvent-enhanced poly-coupling with regioselectivity
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Herein, heterogeneous, inexpensive, metal-free, and environmentally friendly graphene oxide (GO) was developed for the oxidative polycoupling of 2-naphthols in aqueous sodium hydroxide in the presence of air. This study demonstrates that GO can function as a heterogeneous catalyst, and solvent plays a vital role in the coupling. Upon changing the solvent from toluene to water, transformation of products from homocoupling to polycoupling materials occurs.
- Shaikh, Melad,Sahu, Aanchal,Kiran Kumar,Sahu, Mahendra,Singh, Sunil. K.,Ranganath, Kalluri V. S.
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- Oxidation of 2-naphthol in the presence of catalysts based on modified β-cyclodextrins
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The oxidation of 2-naphthol to 1,1'-bi-2-naphthol in a biphasic system in the presence of β-cyclodextrins was studied. It was found that the use of macrocyclic receptors leads to substantial enhancement of the activity of catalytic systems. It was shown that the product yield and the reaction rate substantially increase when ligands obtained via molecular imprinting in the presence of 1,1'-bi-2-naphthol as a template are added.
- Karakhanov,Kardahseva,Maksimov,Egazar'Yants,Karapetyan,Zatolochnaya
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- Oxidative coupling of 2-naphthol catalyzed by a new methoxido bridged dinuclear oxidovanadium(V) complex
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A new dinuclear oxidovanadium(V) complex, [(VO)2(μ-L-κ4O,N,N,O)(μ-OCH3)2(OMe)2]·CH3OH (1), is synthesized by the reaction of V2O5 with 1,1′-((1E,1′E)-hydrazine-1,2-diylidenebis(methanylylidene))bis(naphthalen-2-ol) (H2L) in methanol. H2L is synthesized by two different methods: (i) from the reaction of hydrazine hydrate with 2-hydroxy-1-naphthaldehyde and (ii) from the reaction of hydrazine hydrate with 2-naphthol in the presence of formaldehyde (Mannich condensation). The ligand and its vanadium complex are characterized by elemental analysis, spectroscopic methods (FT-IR, NMR and UV-Vis) and their structures are determined by single crystal X-ray analysis. X-ray studies show that 1 is a neutral dinuclear complex of oxidovanadium(V) in which two vanadium(V) ions are connected by two methoxido bridging groups. The Schiff base ligand is coordinated to both vanadium centers by two NO-donor sets. Complex 1 is employed as initiator for oxidative coupling of 2-naphthol to produce BINOL. The effect of temperature, reaction atmosphere and solvent in catalytic reaction is studied. According to the obtained results, a mechanism is proposed for catalytic oxidative coupling reaction in the presence of complex 1.
- Noshiranzadeh, Nader,Bikas, Rahman,Emami, Marzieh,Siczek, Milosz,Lis, Tadeusz
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- Supramolecular Ammine-Copper rac-BINOLAT Salts through in-situ R- or S-BINOL Racemization
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The molecule rac-1,1'-binaphthalene-2,2'-diol (rac-1,1'-bi-2-naphthol, rac-BINOL) shows a propensity for supramolecular, charge-assisted O–H···O– hydrogen-bonded strand formation when crystallized with its deprotonated form BINOLAT2– and Cu2+ in conc. ammonia. The naphthyl-paneled cavities in the {(rac-BINOLAT2–)(rac-BINOL)2} strands host the [Cu(NH3)5]2+-guest cation through second-sphere N–H···O hydrogen bonding in the structure of [Cu(NH3)5]2+(rac-BINOLAT2–)(rac-BINOL)2. Decreasing the copper(II) and ammonia concentrations in the crystallization leads to {(rac-BINOLAT2–)(rac-BINOL)} strands, in which rac-BINOLAT2– coordinates to two copper(II) atoms in the structure of [Cu(NH3)2(μ-rac-BINOLAT2–-κ2O,O':κO)]2(rac-BINOL)2. In the {Cu2+(NH3)2} moiety two BINOLAT-oxide atoms act as bridging ligands. Both copper structures could be obtained by using the racemic rac-BINOL or the enantiomeric R- or S-BINOL, through an in-situ racemization of the latter.
- Wisser, Barbara,Labahn, Andreas,N?ther, Christian,Janiak, Christoph
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- A practical procedure for the solid-phase synthesis of racemic 2,2'-dihydroxy-1,1'-binaphthyl
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A high yielding solid-phase dimerisation of 2-naphthol by means of a ball-milling procedure is described.
- Rasmussen,Axelsson,Tanner
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- Racemization barriers of 1,1′-binaphthyl and 1,1′-binaphthalene-2,2′-diol: A DFT study
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Density functional theory has been applied to the study of various pathways and transition states for the configurational inversion of 1,1′-binaphthyl (1) and 1,1′-binaphthalene-2,2′-diol (2). The preferred pathway is found to be anti with centrosymmetric transition state. Whereas the reaction path of 1 goes downhill from transition to ground state, in the case of 2 it contains one unexpected local minimum. Very satisfactory agreement with available experimental values of activation Gibbs energies is achieved.
- Meca, Ludek,Reha, David,Havlas, Zdenek
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- A simple, convenient preparation for enantiomerically pure 1,1'-bi-2- naphthols
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A new preparative method for enantiomerically pure 1,1'-bi-2-naphthols is described. 1,1'-Bi-2-naphtholboric anhydride generated from the reaction of racemic 1,1'-bi-2-naphthol and boric acid in toluene is reacted with (S)- proline to produce 1,1'-bi-2-naphtholboric proline anhydride. Its two diastereomers were efficiently separated in THF. After treating successively with NaOH, HCl, and recrystallizing from benzene, enantiomerically pure (S)- and (R)-1,1'-bi-2-naphthol were obtained in 71-79% yield and in 62-74% yield, respectively.
- Shan, Zixing,Xiong, Ying,Li, Weizhong,Zhao, Dejie
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- Photo racemization and polymerization of (R)-1,1′-Bi(2-naphthol)
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(R)-1,1′-Bi(2-naphthol) ((R)-BINOL) in an acetonitrile solution lost optical activity upon irradiation with an Hg-Xe lamp. HPLC resolution of the product indicated that (R)-BINOL was racemized upon irradiation, and SEC analysis suggested that a polymeric product was formed in the course of racemization. It is proposed that polymerization of BINOL can occur before it is racemized and that a unit in a polymer derived from BINOL may lose its optical activity afterwards due to in-chain racemization and/or reduction. The polymeric products seem to consist not only of BINOL residues but also of residues derived from acetonitrile as well as those derived through reduction of BINOL.
- Zhang, Zhaoming,Wang, Yue,Nakano, Tamaki
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- Selective removal of isoquinoline and quinoline from simulated fuel using 1,1′-binaphthyl-2,2′-diol (BINOL): Crystal structure and evaluation of the adduct electronic properties
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1,1′-Binaphthyl-2,2′-diol/quinoline (BINOL/QUN) and 1,1′-binaphthyl-2,2′-diol/isoquinoline (BINOL/ISOQUN) adducts were successfully synthesized. X-ray single crystals of BINOL/QUN and BINOL/ISOQUN were grown and analysed. The crystal packing of the molecules in both adducts confirmed that they are held in aggregates by strong hydrogen bonds (O2-H2?O3), (O3-H3?N1), (O2-H2?O1), (O1-H1?N1), (O2-H2?O1) and weak hydrogen C-H?π bonds. The patterns of the hydrogen bonding network as well as the conformation of BINOL contribute to the formation of the shape of the voids that entrap quinoline and isoquinoline. Molecular modelling which was employed to investigate the electronic properties of BINOL/QUN and BINOL/ISOQUN shows that the HOMO positions of the adducts are localized around the 1,1′-binaphthyl-2,2′-diol (BINOL), while the LUMO is positioned on isoquinoline and quinoline. Thermodynamic parameters obtained from isothermal titration calorimetry (ITC) revealed a stronger isoquinoline/BINOL interaction compared to quinoline/BINOL. 6-Vinyl-1,1′-binaphthyl-2,2′-diol was co-polymerized with styrene to form [DBN-co-STY]. Electrospun [DBN-co-STY] exhibited selectivity for quinoline and isoquinoline in a model simulated fuel presenting an adsorption capacity of 2.2 and 2.4 mg g-1 respectively. The adsorption study showed a higher adsorption capacity for isoquinoline compared to quinoline. This may be attributed to the more favourable electronic properties (HOMO-LUMO properties) of isoquinoline. This concept demonstrates the possibility of extracting/separating isoquinoline and quinoline from fuel.
- Ogunlaja, Adeniyi S.,Hosten, Eric,Betz, Richard,Tshentu, Zenixole R.
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- Regio- and Enantioselective Photodimerization within the Confined Space of a Homochiral Ruthenium/Palladium Heterometallic Coordination Cage
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The photoinduced regio- and enantioselective coupling of naphthols and derivatives thereof is achieved in the confined chiral coordination space of a RuII metalloligand based cage. The racemic or enantiopure cages encapsulate naphthol guests, which then undergo a regiospecific 1,4-coupling, rather than the normal 1,1-coupling, to form 4-(2-hydroxy-1-naphthyl)-1,2-napthoquinones; moderate stereochemical control is achieved with homochiral cages. The photoreactions proceed under both aerobic and anaerobic conditions but through distinct pathways that nevertheless involve the same radical intermediates. This unusual dimerization constitutes a very rare example of asymmetric induction in biaryl coupling by making use of coordination cages with dual functionality—photoredox reactivity and stereoselectivity.
- Guo, Jing,Xu, Yao-Wei,Li, Kang,Xiao, Li-Min,Chen, Sha,Wu, Kai,Chen, Xu-Dong,Fan, Yan-Zhong,Liu, Jun-Min,Su, Cheng-Yong
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- A new family of bis-tetrazole (BIZOL) BINOL-type ligands
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The synthesis and characterization of 5-(1-(2-(1H-tetrazole-5-yloxy)naphthalen-1-yl)naphthalen-2-yloxy)-1H-tetrazole (BIZOL) as the first bis-tetrazole BINOL-type ligands is described.
- Dabbagh, Hossein A.,Najafi-Chermahini, Alireza,Banibairami, Soodabeh
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- Electrophilic dimerization of naphthols in the presence of aluminum halides
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Naphthols undergo dimerization in the presence of an excess of aluminum halides to give mixtures of isomeric hydroxynaphthyltetralones.
- Koltunov, Konstantin Yu.,Chernov, Aleksey N.,Ostashevskaya, Ludmila A.,Gribov, Pavel A.
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- Oxidative coupling of 2-naphthol by zeolite-Y supported homo and heterometallic trinuclear acetate clusters
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Two trinuclear acetate clusters of iron and cobalt of general formula [Fe3O(O2CCH3)6(H2O)3]NO3·2H2O and Fe2Co(O)[(OOCC6H4NO2)6]NO3·2H2O are synthesized and characterized. The synthesized trinuclear clusters are supported on zeolite-Y via an ion exchanged method. FTIR study reveals that the two complexes are tethered via formation of Si-O-H...O-H hydrogen bond linkages with a zeolite-Y matrix. Homogeneous and heterogeneous trinuclear catalysts are found to be efficient catalysts for oxidative coupling of 2-naphthol. Compared to homometallic oxo-clusters, bimetallic complexes are found to show better catalytic activity. Besides obtaining BINOL as a major product, these metal clusters also lead to formation of the tautomeric form of BINOL. The crystal structure of the by-product indicates the formation of a tetrahedral chiral centre in the molecule via the attachment of the solvent. Density Functional Theory (DFT) calculations have been performed to elucidate the structural and electronic properties of both homogeneous and heterogeneous complexes. This journal is
- Das, Sameeran Kr.,Mahanta, Sanjeev P.,Bania, Kusum K.
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- C-C coupling reaction of 1,5-dibromo-2,6-dihydroxynaphthalene with alakli 2-naphthoxide. Opposite effects of counterion coordination and hydrogen bonding on stereoselectivity in the formation of cis- and trans-1,1':5',1''-ternaphthyls
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The title reaction yields cis- and trans-2,2',6',2''-tetrahydroxy-1,1':5',1''-ternaphthyls as the main products. In contrast to non-selective distribution of the stereoisomers in the thermodynamic equilibrium, very high selectivity can be attained under conditions of kinetic control. The observed values of cis-/trans- ratios range between the extremes 94:6 and 6:94, depending on the solvent and counterion employed. The coordination of the metal counterion plays a key role in the reaction performed in toluene, supporting formation of the cis-stereoisomer. When the coordination ability of the counterion is suppressed by 18-crown-6, intramolecular hydrogen bonding of the departing bromide group prevails in the stereocontrol, providing support for the trans-stereoisomer formation.
- Belohradsky, Martin,Budesinsky, Milos,Guenterova, Jana,Hodacova, Jana,Holy, Petr,Zavada, Jiri,Cisarova, Ivana,Podlaha, Jaroslav
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- A simple convenient method for the resolution of racemic 2,2'-dihydroxy-1,1'-binaphthyl using (S)-proline
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The racemic mixture of 2,2'-dihydroxy-1,1'-binaphthyl has been resolved to obtain the R(+) and S(-) enantiomers in essentially pure forms by refluxing with (S)-proline (1eq.) in benzene in three successive operations.
- Periasamy,Bhanu Prasad,Bhaskar Kanth,Kishan Reddy
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- Synthesis and Evaluation of 5,5′-Bitetralone-Based Chiral Phosphoric Acids
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A new type of phosphoric acid bearing a 5,5′-bitetralone scaffold was synthesized from BINOL and was shown to be a highly effective catalyst as illustrated in the asymmetric transfer hydrogenation of 2-phenylquinoline and the Friedel-Crafts reaction of 2,2,2-trifluoroacetophenone.
- Wang, Yazhou,Liu, Wei,Ren, Wenlong,Shi, Yian
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- Visible-Light-Driven di-t-Butyl Peroxide-Promoted the Oxidative Homo- and Cross-Coupling of Phenols
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The visible-light-induced oxidative homo- and cross-coupling of phenols by di-t-butyl peroxide (DTBP) are described. These reactions occur with metal-free process and feature high chemo- and regioselectivity under mild reaction conditions. DTBP is an inexpensive, benign, stable at room temperature, and commercially available oxidizer. It can be irradiated by blue LEDs to generate tert-butoxyl radical (tBuO?), which induces the oxidative homo-coupling of phenols and the cross-coupling of phenols with naphthols, respectively.
- Jia, Hanqiang,He, Min,Yang, Shilei,Yu, Xiaoqiang,Bao, Ming
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- Synthesis of structurally diversified BINOLs and NOBINs via palladium-catalyzed C-H arylation with diazoquinones
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Privileged biaryl frameworks, BINOL and NOBIN, were efficiently constructed with sole 1-DNQs as arylation reagents under one set of reaction conditions. The judicious selection of palladium-catalytic system plays a pivotal role in the excellent selectivities. This transformation accommodated fairly broad substrate generality for both 2-naphthol and N-Boc-2-naphthylamine and afforded the structurally diversified BINOLs and NOBIN derivatives in high efficiency. Notably, the bromo-substituents which cannot survive in conventional palladium-catalyzed reactions were well-compatible with this set of conditions, providing an effective handle for further enriching the library of BINOLs and NOBINs. Preliminary attempts on the asymmetric variant of this reaction were also performed with up to 80:20 er for BINOLs synthesis. [Figure not available: see fulltext.].
- Zhang, Ji-Wei,Jiang, Fei,Chen, Ye-Hui,Xiang, Shao-Hua,Tan, Bin
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p. 1515 - 1521
(2021/07/06)
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- Nickel-Catalyzed Ring-Opening C-O Functionalization of peri-Xanthenoxanthenes for 8-Substituted Binaphthol Synthesis
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Herein, we disclose the Ni-catalyzed ring-opening C-O functionalization of peri-xanthenoxanthenes using Grignard reagents that forms 8-monofunctionalized binaphthols. 1,2-Bis(dicyclohexylphosphino)ethane was the best ligand for alkylations and ICy for arylation. After mechanistic investigations, we assumed that the reaction proceeds via C-O reduction and subsequent C-O functionalization. To verify the mechanism, the intermediate after reduction was isolated. Moreover, the asymmetric addition, using 8-octylbinaphthol after optical resolution, was studied.
- Matsuyama, Naoki,Minamino, Naoto,Shimada, Toyoshi,Kamei, Toshiyuki
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supporting information
p. 3908 - 3912
(2021/05/29)
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- A mild and practical method for deprotection of aryl methyl/benzyl/allyl ethers with HPPh2andtBuOK
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A general method for the demethylation, debenzylation, and deallylation of aryl ethers using HPPh2andtBuOK is reported. The reaction features mild and metal-free reaction conditions, broad substrate scope, good functional group compatibility, and high chemical selectivity towards aryl ethers over aliphatic structures. Notably, this approach is competent to selectively deprotect the allyl or benzyl group, making it a general and practical method in organic synthesis.
- Pan, Wenjing,Li, Chenchen,Zhu, Haoyin,Li, Fangfang,Li, Tao,Zhao, Wanxiang
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p. 7633 - 7640
(2021/09/22)
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- Accurate Understanding the Catalytic Role of MnO2 in the Oxidative-Coupling of 2-naphthols into 1,1′-bi-2-naphthols
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Abstract: It has been reported that β-MnO2 has photocatalytic activity for the oxidative-coupling of 2-naphthols into 1,1′-bi-2-naphthols. Nevertheless, it is hard to exclude the possibility that the oxidative-coupling of 2-naphthols is initiated by β-MnO2 catalysis in dark due to the insufficient investigations in the related reports. In the present work, the oxidative-coupling of 2-naphthols into 1,1′-bi-2-naphthols with different phases MnO2 catalysis in dark and under visible-light irradiation were systematically investigated. The results revealed that the oxidative-coupling of 2-naphthols is jointly initiated by MnO2 catalysis and O2-oxidation, not by MnO2 photocatalysis. Among the α-MnO2, β-MnO2, γ-MnO2 and δ-MnO2 catalysis, β-MnO2 catalysis has the optimal performance, its selectivity for the oxidative-coupling of 2-naphthols into 1,1′-bi-2-naphthols is close to 100%, and its catalytic capacity could be well retained after multiple using. Our findings provide comprehensive and accurate understanding the catalytic role of MnO2 for the oxidative-coupling of 2-naphthols into 1,1′-bi-2-naphthols. Graphic Abstract: In the present work, the oxidative-coupling of 2-naphthols into 1,1′-bi-2-naphthols was proved to be jointly initiated by MnO2 catalysis and O2-oxidation, not by MnO2 photocatalysis. β-MnO2 has the optimal catalytic activity for the oxidative-coupling of 2-naphthols relative to α-MnO2, γ-MnO2 and δ-MnO2. [Figure not available: see fulltext.]
- Wu, Yuting,Yang, Long,Wu, Bo,Li, Jie,Liu, Binyao,Ke, Gaili,Dong, Faqin,Zhou, Yong,He, Huichao
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p. 901 - 908
(2020/08/17)
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- Fe(III) superoxide radicals in halloysite nanotubes for visible-light-assisted benzyl alcohol oxidation and oxidative C[sbnd]C coupling of 2-naphthol
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Selective oxidation of benzyl alcohols to aldehydes and 2-naphthol to BINOL was achieved by activation of molecular oxygen (O2) and hydrogen peroxide (H2O2) over an iron-oxide catalyst embedded in halloysite nanotube. Electron spin resonance spectroscopy (ESR), Raman and in situ FTIR spectroscopic analysis provided direct evidence for the involvement of superoxide radical bound FeIII species in the oxidation reaction. Both the analysis suggested the end-on binding of superoxide radical with FeIII-centre. The stability of such radical bound FeIII-species in halloysite nanotube was analyzed through density functional theory (DFT) calculations. Results suggested that end-on (η1) binding was favourable by 13.5 kcal/ mol than the side-on (η2) binding mode. The formation of such reactive species was believed to play the crucial role in bringing the high selectivity in the catalytic oxidation of benzyl alcohol and oxidative C[sbnd]C coupling of 2-naphthol. UV–Vis spectroscopic studies on the oxidation of benzyl alcohol suggested for the initial adsorption of substrate molecule on the catalyst surface followed by its interaction with FeIII -superoxide/hydroperoxide species generated upon photoirradiation with visible light in presence of O2. The presence of a suitable band gap ~2.14 eV enabled the catalyst to catalyze the reaction under visible light irradiation. Both the reactions (benzyl alcohol and 2-naphthol oxidation) were tested in presence of both O2 and H2O2 as oxidants at ambient temperature. The influence of different parameters like rate of oxygen flow, amount of peroxide, nature of solvent, and catalyst amount on the conversion and selectivity of the reactions were studied to understand their role in the catalytic reactions. Successful oxidation of 2-naphthol with H2O2 as oxidant was a real success to overcome the limitations associated with this reaction using H2O2 as oxidant.
- Baruah, Manash J.,Bora, Tonmoy J.,Dutta, Rupjyoti,Roy, Subhasish,Guha, Ankur Kanti,Bania, Kusum K.
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- Method for efficiently preparing binaphthol through liquid ligand assisted catalysis
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The invention relates to a method for efficiently preparing binaphthol by liquid ligand assisted catalysis, which comprises the following steps: 1) adding 2-naphthol, solid cuprous chloride, liquid diazabicyclo DBU and an n-butyl alcohol solvent into a four-neck flask; 2) installing a thermometer, a heating and stirring device and a reflux condensing pipe on the four-neck bottle; 3) starting to stir at normal pressure, heating to 30-60 DEG C to dissolve the raw materials, introducing air with the flow rate of 100-500ml/min to oxidize the raw materials, and performing reacting at 50-70 DEG C for 3-12 hours to obtain a reaction mixed solution; 4) adding water into the reaction mixed solution, performing stirring, performing heating to 50-90 DEG C, performing washing with water, separating liquid, and removing a wastewater layer to obtain an organic layer; 5) cooling the obtained organic layer to 5-25 DEG C, performing crystallizing, filtering and drying to obtain a white-like binaphtholcrude product, carrying out reduced pressure distillation on the filtrate, and recycling the n-butyl alcohol solvent; and 6) recrystallizing the crude binaphthol product, and performing drying to obtain a white crystallized binaphthol product. The reaction conditions are mild, the product yield is greater than 78%, and the product purity is higher than 99%.
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Paragraph 0034-0045
(2021/03/13)
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- Method for efficiently preparing 1, 1'-bi-2-naphthol under catalysis assistance of solid ligand
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The invention relates to a method for efficiently preparing 1, 1'-bi-2-naphthol under catalysis assistance of solid ligand; the method comprises the following steps: 1), adding 2-naphthol, solid cuprous chloride, solid phenanthroline and an n-butyl alcohol solvent into a four-neck flask; 2), installing a thermometer, a heating and stirring device and a reflux condensing pipe on the four-neck bottle; 3), starting to stir at normal pressure, performing heating to dissolve, introducing air to oxidize, and performing heating to react to obtain a reaction mixed solution; 4), adding water into the reaction mixed solution, performing stirring, performing heating, performing washing with water, separating liquid, and removing a wastewater layer to obtain an organic layer; 5), cooling, crystallizing, filtering and drying the organic layer to obtain an off-white 1, 1'-bi-2-naphthol crude product, carrying out reduced pressure distillation on the filtrate, and recycling the n-butyl alcohol solvent; and 6), performing recrystallizing and drying to obtain a white crystal 1, 1'-bi-2-naphthol product. The reaction temperature is low, the reaction conditions are mild, the yield of the product obtained by recrystallization after the reaction is greater than 80%, and the purity of the product is higher than 99.3%.
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Paragraph 0033-0044
(2021/03/31)
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- A chemo- And regioselective Pd(0)-catalyzed three-component spiroannulation
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A chemo- and regioselective Pd(0)-catalyzed spiroannulation has been successfully developed. The key feature of this method is the use of readily available 1,2-dihaloarenes, alkynes and 2-naphthols for the rapid assembly of spirocarbocyclic molecules. Mechanistic studies revealed that this domino reaction proceeded through a cascade of oxidative addition to Pd(0), alkyne migratory insertion, and 2-naphthol-facilitated dearomatizing [4+1] spiroannulation.
- Wu, Jiaoyu,Bai, Lu,Han, Lingbo,Liu, Jingjing,Luan, Xinjun
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supporting information
p. 1117 - 1120
(2021/02/06)
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- Mechanistic Investigation of a Synthetic Route to Biaryls by the Sigmatropic Rearrangement of Arylsulfonium Species
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A comprehensive mechanistic investigation was conducted on the coupling reaction of aryl sulfoxides with phenols by using trifluoroacetic anhydride to yield biaryls. NMR experiments revealed that our previously proposed mechanism, which consists of a cascade of an interrupted Pummerer reaction and a rate-determining [3,3] sigmatropic rearrangement, is reasonable. The electronic effects of the substrates were also evaluated to elucidate the nature of the rearrangement step. Based on experimental observations and theoretical calculations, we conclude that the rearrangement is highly asynchronous and stepwise rather than concerted when electron-rich phenols are employed for the reaction.
- Yanagi, Tomoyuki,Yorimitsu, Hideki
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supporting information
p. 13450 - 13456
(2021/08/23)
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- Iron-Catalyzed Oxidative C?C Cross-Coupling Reaction of Tertiary Anilines with Hydroxyarenes by Using Air as Sole Oxidant
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A mild procedure for the oxidative C?C cross-coupling of tertiary anilines with phenols is described which provides the products generally in high yields and with excellent selectivity. The reaction is catalyzed by the hexadecafluorinated iron–phthalocyanine complex FePcF16 in the presence of substoichiometric amounts of methanesulfonic acid and ambient air as sole oxidant.
- Purtsas, Alexander,Kataeva, Olga,Kn?lker, Hans-Joachim
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p. 2499 - 2508
(2020/02/11)
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- Mixed er-NHC/phosphine Pd(ii) complexes and their catalytic activity in the Buchwald-Hartwig reaction under solvent-free conditions
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A series of novel (NHC)PdCl2-PR3 complexes were synthesized and fully characterized by 1H, 13C, 31P NMR and FT-IR spectroscopy. These complexes showed high catalytic activity toward solvent-free Buchwald-Hartwig amination. Both primary and secondary amines were efficiently utilized under the same reaction conditions. The solvent-free synthesis of valuable N-aryl carbazoles and similar N-heterocyclic systems was described.
- Ageshina, Alexandra A.,Sterligov, Grigorii K.,Rzhevskiy, Sergey A.,Topchiy, Maxim A.,Chesnokov, Gleb A.,Gribanov, Pavel S.,Nechaev, Mikhail S.,Asachenko, Andrey F.,Bermeshev, Maxim V.,Melnikova, Elizaveta K.
-
supporting information
p. 3447 - 3452
(2019/04/30)
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- The Interrupted Pummerer Reaction in a Sulfoxide-Catalyzed Oxidative Coupling of 2-Naphthols
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A benzothiophene S-oxide catalyst, generated in situ by sulfur oxidation with H2O2, mediates the oxidative coupling of 2-naphthols. Key to the catalytic process is the capture and inversion of reactivity of a 2-naphthol partner, using an interrupted Pummerer reaction of an unusual benzothiophene S-oxide, followed by subsequent coupling with a second partner. The new catalytic manifold has been showcased in the synthesis of the bioactive natural products, (±)-nigerone and (±)-isonigerone. Although Pummerer reactions are used widely, their application in catalysis is rare, and our approach represents a new catalytic manifold for metal-free C?C bond formation.
- He, Zhen,Pulis, Alexander P.,Procter, David J.
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supporting information
p. 7813 - 7817
(2019/05/15)
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- An enantioselective oxidative coupling reaction of 2-naphthol derivatives catalyzed by chiral diphosphine oxide-iron(ii) complexes
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An enantioselective oxidative coupling of 2-naphthol derivatives is developed with the use of chiral Fe(ii)-diphosphine oxide complexes. Optically active 1,1-bi-2-naphthol derivatives can be synthesized in high yields when a 2?:?1 complex of (S)-xylyl-iPrO-BIPHEP-oxide and Fe(OTf)2 is used in the presence of t-butyl hydroperoxide as an oxidant. The non-linear effect, X-ray crystal structure and ESI-MS suggest that a 2?:?1 complex of (S)-xylyl-iPrO-BIPHEP-oxide and Fe(OTf)2 is a pre-catalyst for a Fe(iii)/Fe(iv) redox cycle.
- Horibe, Takahiro,Nakagawa, Keita,Hazeyama, Takashi,Takeda, Kazuki,Ishihara, Kazuaki
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supporting information
p. 13677 - 13680
(2019/11/19)
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- Pd-Au-Y as Efficient Catalyst for C-C Coupling Reactions, Benzylic C-H Bond Activation, and Oxidation of Ethanol for Synthesis of Cinnamaldehydes
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Pd-Au nanoalloy supported on zeolite-Y (Pd-Au-Y) matrix was found to be an effective catalyst for C-Cl bond activation and oxidative coupling of 2-naphthol, leading to the formation of various biaryl products and 1,1′-bi-2-naphthol, BINOL. The same catalyst was also highly efficient for selective oxidation of benzylic alcohols to benzaldehydes. Cinnamaldehydes were obtained directly from benzaldehydes by aldol condensation with acetaldehyde generated in situ by partial oxidation of ethanol in the presence of Pd-Au-Y catalyst at 120 °C under basic condition. The biaryl products were also obtained directly from benzylic alcohols in a one-pot system by reacting with phenylboronic acid. The formation of biaryls from benzylic alcohols was believed to occur via one-pot benzylic C-H and C-Cl bond activation. A high % yield of biaryls, BINOL, aldehydes, and cinnamaldehydes was obtained by performing different reactions using the single Pd-Au-Y catalyst. The strong interaction of chloro-benzylic alcohol was predominantly located at active gold species. X-ray photoelectron and diffuse reflectance spectroscopic studies revealed the strong interaction between Pd and Au particles. Electrochemical studies provided proper evidence for the individual role of the nanoparticles (NPs) in one-pot synthesis of biaryls from benzylic alcohols.
- Sharma, Mukesh,Das, Biraj,Baruah, Manash J.,Biswas, Subir,Roy, Subhasish,Hazarika, Anil,Bhargava, Suresh K.,Bania, Kusum K.
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p. 5860 - 5875
(2019/06/17)
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- Continuous flow solvent free organic synthesis involving solids (reactants/products) using a screw reactor
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Here we report for the first-time various organic transformations such as aldol condensation, oxidation, nucleophilic substitutions, protection, acylations and coupling reactions using a mechanochemical approach at a controlled temperature using a single synthesis platform. Almost minimal solvents or solvent-free conditions are used, making it a very efficient and clean synthesis of various products. A jacketed screw reactor when operated at different temperatures (0 °C to 160 °C) and over a range of rotation speeds for changing the residence time (15 s-300 s) helped to achieve maximum conversion. This approach is also extended to the synthesis using substrates having different substitutions, heterocycles and steric hindrance.
- Sharma, Brijesh M.,Atapalkar, Ranjit S.,Kulkarni, Amol A.
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supporting information
p. 5639 - 5646
(2019/10/22)
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- Tetrafluoropyridyl (TFP): a general phenol protecting group readily cleaved under mild conditions
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Phenols are extremely valuable building blocks in the areas of pharmaceuticals, natural products, materials and catalysts. In order to carry out modifications on phenols, the phenolic oxygen is routinely protected to prevent unwanted side reactions. Presently many of the protecting groups available can require harsh conditions, specialist equipment, expensive or air/moisture-sensitive reagents to install and remove. Here we introduce the use of the tetrafluoropyridyl (TFP) group as a general protecting group for phenols. TFP can be installed in one step with no sensitivity to water or air, and it is stable under a range of commonly employed reaction conditions including acid and base. The TFP protecting group is readily cleaved under mild conditions with quantitative conversion to the parent phenol, observed in many cases in less than 1 hour.
- Brittain, William D. G.,Cobb, Steven L.
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supporting information
p. 2110 - 2115
(2019/02/27)
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- Photochemical Oxidative Coupling of 2-Naphthols using a Hybrid Reduced Graphene Oxide/Manganese Dioxide Nanocomposite under Visible-Light Irradiation
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We describe a simple, cost-effective, efficient, and high-yielding photocatalytic approach for the oxidative self-dimerization of 2-naphthols using a semiconductor–metal hybrid that consists of intercalated manganese dioxide nanoparticles in reduced graphene oxide (rGO/MnO2) under visible-light irradiation. The desired photocatalyst was synthesized in a single step by mixing MnO2 nanoparticles with rGO ultrasonically. The hybrid photocatalyst exhibited a significantly higher activity than neat MnO2 nanoparticles and rGO, which is believed to be because of the synergistic effect of its components. To our knowledge, this hybrid rGO/MnO2 nanocomposite is the first heterogeneous, green photocatalyst for the oxidative coupling of 2-naphthols under mild conditions.
- Kumar, Anurag,Aathira,Pal, Ujjwal,Jain, Suman L.
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p. 1844 - 1852
(2018/02/12)
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- Cobalt-Catalyzed Aerobic Cross-Dehydrogenative Coupling of C-H and Thiols in Water for C-S Formation
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Organosulfides have great significance and value in synthetic and biological chemistry. To establish a versatile and green methodology for C-S bond generation, we successfully developed a new aerobic cross-dehydrogenative coupling of C-H and S-H to synthe
- Huang, Xin,Chen, Yongqi,Zhen, Shan,Song, Lijuan,Gao, Mingqi,Zhang, Panke,Li, Heng,Yuan, Bingxin,Yang, Guanyu
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p. 7331 - 7340
(2018/07/29)
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- Selective, Catalytic, and Metal-Free Coupling of Electron-Rich Phenols and Anilides Using Molecular Oxygen as Terminal Oxidant
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Selective oxidative homo- and cross-coupling of electron-rich phenols and anilides was developed using nitrosonium tetrafluoroborate as a catalyst. Oxidative coupling of phenols revealed unusual selectivities, which translated into the unprecedented synthesis of inverse Pummerer-type ketones. Mechanistic studies suggest that oxidative coupling of phenols and anilides shares a common pathway via homolytical heteroatom-hydrogen bond cleavage. Nitrosonium salt catalysis was applied for cross-dehydrogenative coupling initiated by generation of heteroatom-centered radicals.
- Bering, Luis,Vogt, Melina,Paulussen, Felix M.,Antonchick, Andrey P.
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supporting information
p. 4077 - 4080
(2018/07/15)
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- Iron(II) Chloride-Catalyzed Nitrene Transfer Reaction for Dearomative Amination of β-Naphthols with Aryl Azides
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A first example of Fe-catalyzed dearomative amination of β-naphthols with aryl azides is described. The method constructs a nitrogen-containing quaternary carbon center catalyzed by cheap and readily available iron salt FeCl2, and affords a series of α-amino-β-naphthalenones in good to excellent yields under simple and mild reaction conditions. Preliminary experimental and computational studies suggest that the reaction is probably initiated by iron-iminyl diradical and followed by intramolecular hydrogen transfer to generate iron-aminyl radical and finally an intramolecular radical combination reaction. (Figure presented.).
- Wu, Dun-Qi,Guan, Zhen-Yu,Peng, Yi,Sun, Jian,Zhong, Cheng,Deng, Qing-Hai
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p. 4720 - 4725
(2018/11/23)
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- Lipase-Catalyzed Dynamic Kinetic Resolution of C1- and C2-Symmetric Racemic Axially Chiral 2,2′-Dihydroxy-1,1′-biaryls
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We have discovered that the racemization of configurationally stable, axially chiral 2,2′-dihydroxy-1,1′-biaryls proceeds with a catalytic amount of a cyclopentadienylruthenium(II) complex at 35–50 °C. Combining this racemization procedure with lipase-catalyzed kinetic resolution led to the first lipase/metal-integrated dynamic kinetic resolution of racemic axially chiral biaryl compounds. The method was applied to the synthesis of various enantio-enriched C1- and C2-symmetric biaryl diols in yields of up to 98 % and enantiomeric excesses of up to 98 %, which paves the way for new developments in the field of asymmetric synthesis.
- Moustafa, Gamal A. I.,Oki, Yasuhiro,Akai, Shuji
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supporting information
p. 10278 - 10282
(2018/05/30)
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- Regioselective and Chemoselective Reduction of Naphthols Using Hydrosilane in Methanol: Synthesis of the 5,6,7,8-Tetrahydronaphthol Core
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A regioselective and chemoselective method for catalytic synthesis of biologically interesting 5,6,7,8-tetrahydronaphthols by reduction of naphthols was described. The side aromatic hydrocarbons in naphthols were site-selectively reduced, using hydrosilanes in methanol, allowing for retaining functional phenol scaffolds intact. It presents a rare example of using low-cost and air-stable hydrosilane for catalytic reduction of unactivated aromatic hydrocarbons under mild conditions. This reaction is scalable and proceeds in high selectivity without the formation of 1,2,3,4-tetrahydronaphthol byproducts with toleration of sensitive functionalities such as bromide, chloride, fluoride, ketone, ester, and amide.
- He, Yuan,Tang, Jinghua,Luo, Meiming,Zeng, Xiaoming
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supporting information
p. 4159 - 4163
(2018/07/29)
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- KHF2: A mild and selective desilylating agent for phenol tert-butyldimethylsilyl (TBDMS) ethers
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TBDMS (t-BuMe2Si, tert-butyldimethylsilyl) ethers of a variety of phenols have been deprotected with KHF2 in MeOH, at room temperature. Carboxylic ester and labile phenolic acetate were unaffected under these conditions. In competition reactions between TBDMS ethers of a phenol and two primary benzylic alcohols, the phenolic ether underwent cleavage whereas the alcohol ethers remained intact. From a substrate containing both a phenolic hydroxyl group and a secondary, doubly benzylic hydroxyl group protected as TBDMS ethers, the phenol was rapidly and selectively released. Cleavage of TBDMS, TBDPS, and TIPS ethers of a phenol was also compared. TBDMS and TBDPS ethers underwent cleavage at room temperature within 30 minutes, whereas removal of the TIPS ether required 2.5 hours. Ease of cleavage appears to be TBDMS ≈ TBDPS > TIPS. At 60°C, TBDMS ethers of primary benzylic, allylic, and unactivated alcohols can be efficiently desilylated over a prolonged period (13-17 h). Thus, KHF2 proves to be a mild and effective reagent for the selective desilylation of phenol TBDMS ethers at room temperature.
- Lakshman, Mahesh K.,Tine, Fatou A.,Khandaker, Tashrique A.,Basava, Vikram,Agyemang, Nana B.,Benavidez, Michael S.A.,Ga?i, Marikone,Guerrera, Lisa,Zajc, Barbara
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supporting information
p. 381 - 385
(2017/02/10)
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- Synthetic Transformations Using Molecular Oxygen-Doped Carbon Materials
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Carbon materials like activated carbon (AC) undergo chemisorption with O2 to give species with electron deficiency in the carbon skeleton and negative charge at the oxygen end that upon reaction with PPh3 and benzoic acid afford Phs
- Periasamy, Mariappan,Shanmugaraja, Masilamani,Reddy, Polimera Obula,Ramusagar, Modala,Ananda Rao, Gunda
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p. 4944 - 4948
(2017/05/12)
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- Solvent-controlled selective synthesis of biphenols and quinones: Via oxidative coupling of phenols
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A regioselective synthesis of unsymmetrical and symmetrical biphenols and binaphthols via oxidative coupling of phenols or naphthols in the presence of K2S2O8 in CF3COOH under ambient conditions is described. Interestingly, the 1:1 ratio of H2O and CH3CN solvent mixtures at 80 °C instead of CF3COOH provided substituted unsymmetrical quinones. A gram-scale synthesis of biphenols and binaphthols was demonstrated.
- More, Nagnath Yadav,Jeganmohan, Masilamani
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supporting information
p. 9616 - 9619
(2017/09/01)
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- Regioselective Construction of Functionalized Biarylols by Fe(OTf)3-Catalyzed Direct Arylation of 1-Diazonaphthalen-2(1H)-ones and Their Fluorescence Properties
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A facile and efficient protocol for the construction of functionalized biarylols by Fe(OTf)3-catalyzed direct arylation of 1-diazonaphthalen-2(1H)-ones with arenes has been developed. This methodology provides diverse 1-arylnaphthalen-2-ols in moderate to good yields. This approach has also been applied to the synthesis of biologically interesting polycyclic-aromatic-substituted and heteroaryl-substituted naphthalen-2-ols. The synthesized compounds bearing an anthracene scaffold can be useful as potential fluorescent biomarkers for confocal imaging of clone cells.
- Somai Magar, Krishna Bahadur,Edison,Lee, Yong Rok
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p. 7046 - 7054
(2017/12/28)
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- Meso-Tetraphenylporphyrin Iron Chloride Catalyzed Selective Oxidative Cross-Coupling of Phenols
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A novel catalytic system for oxidative cross-coupling of readily oxidized phenols with poor nucleophilic phenolic partners based on an iron meso-tetraphenylporphyrin chloride (Fe[TPP]Cl) complex in 1,1,1,3,3,3-hexafluoropropan-2-ol (HFIP) was developed. The unique chemoselectivity of this reaction is attributed to the coupling between a liberated phenoxyl radical with an iron-ligated phenolic coupling partner. The conditions are scalable for preparing a long list of unsymmetrical biphenols assembled from a less reactive phenolic unit substituted with alkyl or halide groups.
- Shalit, Hadas,Libman, Anna,Pappo, Doron
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supporting information
p. 13404 - 13413
(2017/10/05)
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- Enantioselective Oxidative Homocoupling and Cross-Coupling of 2-Naphthols Catalyzed by Chiral Iron Phosphate Complexes
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Novel chiral iron phosphate complexes were prepared as catalysts for asymmetric oxidative coupling reactions. These catalysts were applied for the synthesis of enantio-enriched C1- and C2-symmetric BINOLs, in which the 3 and 3′ positions are available for chemical modifications. It was proposed that the reaction takes place via an oxidative radical-anion coupling mechanism. A destructive BINOL racemization that competes with the enantioselective oxidative coupling of 2-naphthols was revealed, thereby offering new insights into this highly important reaction.
- Narute, Sachin,Parnes, Regev,Toste, F. Dean,Pappo, Doron
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supporting information
p. 16553 - 16560
(2016/12/27)
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- Synthesis of bridged biarylbisquinones and effects of biaryl dihedral angles on photo- and electro-chemical properties
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A series of bridged biarylbisquinones, QBINOLs 1-4, and their corresponding monomers, QNaphs 5-6, were designed to demonstrate the influence of biaryl conformation on the photo- and electro-chemical properties of the molecules. All target compounds were synthesized from the Diels-Alder reaction between silyl enol ethers of the corresponding naphthyl or binaphthyl derivatives and p-benzoquinone. Addition of an OMe auxochrome or formation of the dimeric structures affect the absorption spectra and the energy band gap (Eg), but not the reduction potentials of the molecules. Narrowing the dihedral angles of the QBINOLs by shortening methylene bridges limited the contribution of bridging OR auxochromes and therefore resulted in lower HOMO levels and larger Eg.
- Wongma, Krittaphat,Bunbamrung, Nantiya,Thongpanchang, Tienthong
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p. 1533 - 1540
(2016/03/01)
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- Tetrahydro-1,4-epoxynaphthalene-1-carboxylic acid: a chiral resolving agent for the resolution and absolute configuration assignment of 7,7'-disubstituted 1,1'-bi-2-naphthols
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Tetrahydro-1,4-epoxynaphthalene-1-carboxylic acid (THENA), was applied as a chiral derivatizing agent to resolve 7,7'-disubstituted 1,1'-bi-2-naphthol derivatives. This process is very efficient and could potentially be used as a preliminary tool to assign the absolute configuration of substituted 1,1'-bi-2-naphthols by means of a simple TLC.
- Dolsophon, Kulvadee,Ruangsupapichat, Nopporn,Soponpong, Jakapun,Sungsuwan, Suttipun,Prabpai, Samran,Kongsaeree, Palangpon,Thongpanchang, Tienthong
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p. 1113 - 1120
(2016/11/11)
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- A novel type of catalysts for asymmetric oxidative coupling of 2-naphthol
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Stereochemically inert, positively charged chiral octahedral complexes of CoIII and CrIII were used as catalysts for asymmetric oxidative coupling of 2-naphthol. The reaction product 1,1′-bi-2-naphthol was produced with a yield of up to 74% and enantiomeric excess of up to 22%. The reduction and oxidation potentials of a series of CoIII and CrIII cationic complexes were measured.
- Larionov,Peregudova,Maleev,Belokon, Yu. N.
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p. 685 - 688
(2016/12/27)
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- Synthesis of enantiomerically pure helicene-like mono 1,3-oxazines from 1,1′-binaphthyl-2,2′,7-triol and study of their chiroptical properties
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A method was developed to synthesize 1,1′-binaphthyl-2,2′,7-triol by an oxidative cross coupling reaction of 2-hydroxy naphthalene and 2,7-dihydroxy naphthalene. A process was optimized to separate the enantiomers of this compound by making its complex with S-brucine; its absolute configuration was established and it was converted into a series of helicene-like mono 1,3-oxazines. The chiroptical properties of these molecules were investigated and it was established that the helicene-like structural element contributes more to the optical rotation as compared to the stereogenic center.
- Sundar, M. Shyam,Bedekar, Ashutosh V.
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p. 46258 - 46269
(2016/06/06)
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- Amino acid derived CuII compounds as catalysts for asymmetric oxidative coupling of 2-naphthol
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We report the synthesis and characterization of several novel aminopyridine-l-amino acid derived CuII-complexes. The ligands are prepared by a one-pot reductive alkylation of the l-amino acid scaffold and the respective aminopyridine CuII-complexes were obtained by reaction with CuCl2 or Cu(acetato)2. All compounds were characterized by spectroscopic techniques, as well as ESI-MS. Two of the CuII-complexes were characterized by single-crystal X-ray diffraction, one of them, [CuII(L)(CH3COO)] (HL = (S)-3-phenyl-2-(pyridin-2-ylmethylamino)propanoic acid), being the first ever reported aminopyridine-class CuII complex bearing a tridentate N,N,O donor set and a monodentate acetato ligand. The complexes are tested as catalysts in the oxidative coupling of 2-naphthol in organic solvent-water mixtures using dioxygen as the terminal oxidant. The effect of variables such as ligand denticity and substituents, as well as solvent, temperature and oxidant intake, on the overall performance is studied. In general, moderate to low conversions of 2-naphthol to 1,1′-bi-2-naphthol (BINOL) are obtained. The catalysts also showed moderate to low enantioselectivity. Some aspects of the reaction mechanism were elucidated by spectroscopy, electrochemical and theoretical studies. It was found that basic additives are important for activity, but these also increase the formation of secondary oxidation products. The addition of peroxide scavengers such as KI resulted in an increase of conversion, the yield of BINOL and enantioselectivity. This journal is
- Ado, Pedro,Barroso, Snia,Carvalho, M. Fernanda N. N.,Teixeira, Carlos M.,Kuznetsov, Maxim L.,Costa Pessoa, Joo
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supporting information
p. 1612 - 1626
(2015/02/19)
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- Oxidative Cross-Coupling of Two Different Phenols: An Efficient Route to Unsymmetrical Biphenols
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An efficient synthesis of unsymmetrical biphenols via the oxidative cross-coupling of two different phenols in the presence of K2S2O8 and Bu4N+·HSO3- (10 mol %) in CF3COOH at ambient conditions is described. 1:1 Cross-coupling of substituted phenols with naphthols and 1:2 cross-coupling of naphthols with phenol are also disclosed. By using Bu4N+·HSO3-, the homocoupling of phenols or naphthols was controlled. In these reactions, the ortho C-H bond of two different phenols and the ortho and para C-H bond of phenols were coupled together.
- More, Nagnath Yadav,Jeganmohan, Masilamani
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p. 3042 - 3045
(2015/06/30)
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- Efficient Microwave Method for the Oxidative Coupling of Phenols
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The tert-butyl peroxide-initiated, oxidative coupling of phenols can frequently promote reactions that otherwise perform poorly under alternative conditions. Despite this utility, peroxide coupling reactions employing conventional heat often require high-
- Grant-Overton, Sharday,Buss, Joshua A.,Smith, Eva H.,Gutierrez, Elisa G.,Moorhead, Eric J.,Lin, Vivian S.,Wenzel, Anna G.
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supporting information
p. 331 - 337
(2015/10/29)
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- Carbocatalysed Oxidative C sp 2 -C sp 2 Homocouplings of Benzo-Fused Heterocycles
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Appropriate and fine-tuned treatments of amorphous carbon (AC) involving aqua regia or concentrated HNO3 lead to oxidised carbon materials (oAC) which are able to catalyse 2,2′- and 3,3′-homocouplings of various functionalised indoles with outs
- Wirtanen, Tom,M?kel?, Mikko K.,Sarfraz, Jawad,Ihalainen, Petri,Hietala, Sami,Melchionna, Michele,Helaja, Juho
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supporting information
p. 3718 - 3726
(2016/01/25)
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- Oxidative coupling of 2-naphthol to (R)/(S)-BINOL by MCM-41 supported Mn-chiral Schiff base complexes
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Three Mn(III)-chiral Schiff base complexes supported on MCM-41 are found to be effective reusable catalysts for enantioselective oxidation of 2-naphthol to (R)- and (S)-BINOL (1,1′ bi-2-naphthol) in the presence of oxygen. The supported Mn(III)-complexes are characterized by PXRD, FTIR, solid state-NMR, BET, and cyclic voltammetry study. The homo-coupling reaction with oxygen as the oxidant is promoted by 20 mg of Mn(III) Schiff base complexes to afford binaphthols in nearly quantitative yields with high enantioselectivity of up to 91% ee. The catalytic activities of the homogeneous and heterogeneous chiral catalyst are found to be almost similar. However, the heterogeneous counterparts are found to be advantageous in terms of recyclability and storability. Oxygen partial pressure, the nature of the solvent, temperature and the amount of catalyst affect the catalytic oxidation process. High temperature and highly polar solvent are found to have adverse effects on the catalytic oxidation process.
- Bania, Kusum K.,Karunakar,Satyanarayana, Lanka
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p. 33185 - 33198
(2015/04/27)
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- Synthesis and Study of 7,12,17-Trioxa[11]helicene
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Synthesis of the title compound 7,12,17-trioxa[11]helicene, a large oxygen-containing helicene, has been reported. The 11-membered heterohelicene was synthesized by a combination of two simple reactions involving oxidative coupling and dehydrative cyclization. The final helicene was characterized by single-crystal X-ray diffraction, fluorescence spectroscopy, and differential scanning calorimetric analysis.
- Shyam Sundar,Bedekar, Ashutosh V.
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supporting information
p. 5808 - 5811
(2015/12/11)
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- {Cu2+-Co3+-Cu2+} and {Cu2+-Fe3+-Cu2+} heterobimetallic complexes and their catalytic properties
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We report on the heterobimetallic complexes {Cu+-Co3+-Cu+} (3), {Cu+-Fe3+-Cu+} (4), {Cu2+-Co3+-Cu2+} (5), and {Cu2+-Fe3+-Cu2+} (6) and show their catalytic applications in the oxidation of hindered phenols and the oxidative coupling of terminal alkynes. The former reaction produces C-C-coupled and dealkylated products, whereas the latter leads to the homo- and heterocoupling of terminal alkynes. The facile redox interconversion between Cu+ and Cu2+ for the secondary metal ions in these heterobimetallic complexes appears to be essential for the observed catalysis, and an important design aspect is better substrate accessibility and the use of molecular oxygen as the sole oxidant. Heterobimetallic complexes {Cu+-Co3+-Cu+} (3), {Cu+-Fe3+-Cu+} (4), {Cu2+-Co3+-Cu2+} (5), and {Cu2+-Fe3+-Cu2+} (6) have been used as catalysts for the oxidation of substituted phenols and the oxidative homo- and heterocoupling of terminal alkynes.
- Srivastava, Sumit,Ali, Afsar,Tyagi, Adish,Gupta, Rajeev
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p. 2113 - 2123
(2015/04/27)
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- Biaryl-based anion receptors bearing thiourea groups: Fluoride anion receptor
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The synthesis, characterization and binding studies with anions for biaryl-based anion receptors bearing thiourea groups have been described. The results revealed that receptors (1 and 2) showed good selectivity and binding affinity for F-, and among them binaphthyl-based receptor (1a) showed the best binding affinity for F-in comparison to other tested anions (Cl-, Br-, I-, NO-3 ; HSO-4 ; AcO-And H2PO-4 ). This is probably due to the fact that the moderate rigidity of binaphthyl skeleton in 1a is able to provide the better geometry of two thiourea groups for incorporating F-into the binding pocket. The higher basicity of F-Also participated in this selectivity. Springer Science+Business Media Dordrecht 2013.
- Takahashi, Yohei,Endo, Masatoshi,Ito, Kazuaki
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p. 237 - 245
(2014/06/09)
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- Enantioselective oxidative-coupling of polycyclic phenols
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Enantioselective oxidative-coupling of polycyclic phenols, such as 2-anthracenol, 9- or 3-phenanthrol, and 5-chrysenol was established by using vanadium(V/IV) catalysis under air or O2 as a co-oxidant. In the vanadium catalyzed reaction, the co
- Takizawa, Shinobu,Kodera, Junpei,Yoshida, Yasushi,Sako, Makoto,Breukers, Stefanie,Enders, Dieter,Sasai, Hiroaki
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p. 1786 - 1793
(2014/03/21)
-