- Selective O -alkylation of 2-naphthol using phosphonium-based ionic liquid as the phase transfer catalyst
-
The selective preparation of O-alkylated aromatic products from substituted phenol and naphthols is challenging. The O-alkylation of 2-naphthol with benzyl chloride has been studied in this work using phosphonium-based ionic liquids as catalysts such as trihexyl(tetradecyl)phosphonium chloride (THTDPC), trihexyl(tetradecyl)phosphonium bromide (THTDPB), trihexyl(tetradecyl) phosphonium decanoate (THTDPD), and trihexyl(tetradecyl)phosphonium hexafluorophosphate (THTDPH). This is a liquid-liquid phase-transfer-catalysed reaction with reuse of catalyst. The effects of various parameters such as agitation speed, various phosphonium-based ionic liquids, phase volume ratio, catalyst concentration, NaOH concentration, mole ratio of starting materials, and temperature were studied systematically to understand the conversion patterns and the selectivity of the desired product. A mechanism of the reaction and a kinetic model are proposed.
- Yadav, Ganapati D.,Tekale, Smruti P.
-
-
Read Online
- Transition-Metal-Free and Base-Promoted Carbon-Heteroatom Bond Formation via C-N Cleavage of Benzyl Ammonium Salts
-
A facile and general method for constructing carbon-heteroatom (C-P, C-O, C-S, and C-N) bonds via C-N cleavage of benzyl ammonium salts under transition-metal-free conditions was reported. The combination of t-BuOK and 18-crown-6 enabled a wide range of substituted benzyl ammonium salts to couple readily with different kinds of heteroatom nucleophiles, i.e. hydrogen phosphoryl compounds, alcohols, thiols, and amines. Good functional group tolerance was demonstrated. The scale-up reaction and one-pot synthesis were also successfully performed.
- Liu, Long,Tang, Yuanyuan,Wang, Kunyu,Huang, Tianzeng,Chen, Tieqiao
-
p. 4159 - 4170
(2021/03/09)
-
- Cross-Coupling Reactions of Aryl Halides with Primary and Secondary Aliphatic Alcohols Catalyzed by an O,N,N-Coordinated Nickel Complex
-
A synthesis of alkyl aryl ethers was achieved via the cross-coupling of aryl halides with primary and secondary aliphatic alcohols catalyzed by a bench-stable nickel complex supported by a monoanionic O,N,N-tridentate ligand. This nickel-catalyzed reaction proceeds smoothly in the absence of a phosphine ligand, affording alkyl aryl ethers in moderate to good yields. (Figure presented.).
- Hashimoto, Toru,Shiota, Keisuke,Funatsu, Kei,Yamaguchi, Yoshitaka
-
supporting information
p. 1625 - 1630
(2021/01/26)
-
- Photocatalytic Reductive C-O Bond Cleavage of Alkyl Aryl Ethers by Using Carbazole Catalysts with Cesium Carbonate
-
Methods to activate the relatively stable ether C-O bonds and convert them to other functional groups are desirable. One-electron reduction of ethers is a potentially promising route to cleave the C-O bond. However, owing to the highly negative redox potential of alkyl aryl ethers (Ered -2.6 V vs SCE), this mode of ether C-O bond activation is challenging. Herein, we report the visible-light-induced photocatalytic cleavage of the alkyl aryl ether C-O bond using a carbazole-based organic photocatalyst (PC). Both benzylic and non-benzylic aryl ethers underwent C-O bond cleavage to form the corresponding phenol products. Addition of Cs2CO3 was beneficial, especially in reactions using a N-H carbazole PC. The reaction was proposed to occur via single-electron transfer (SET) from the excited-state carbazole to the substrate ether. Interaction of the N-H carbazole PC with Cs2CO3 via hydrogen bonding exists, which enables a deprotonation-assisted electron-transfer mechanism to operate. In addition, the Lewis acidic Cs cation interacts with the substrate alkyl aryl ether to activate it as an electron acceptor. The high reducing ability of the carbazole combined with the beneficial effects of Cs2CO3 made this otherwise formidable SET event possible.
- Yabuta, Tatsushi,Hayashi, Masahiko,Matsubara, Ryosuke
-
p. 2545 - 2555
(2021/02/01)
-
- Enantioselective Ni-Catalyzed Electrochemical Synthesis of Biaryl Atropisomers
-
A scalable enantioselective nickel-catalyzed electrochemical reductive homocoupling of aryl bromides has been developed, affording enantioenriched axially chiral biaryls in good yield under mild conditions using electricity as a reductant in an undivided cell. Common metal reductants such as Mn or Zn powder resulted in significantly lower yields in the absence of electric current under otherwise identical conditions, underscoring the enhanced reactivity provided by the combination of transition metal catalysis and electrochemistry.
- Chen, Song,Chen, Yue-Gang,Gao, Pei-Sen,Liu, Dong,Ma, Hong-Xing,Mei, Tian-Sheng,Qiu, Hui,Shuai, Bin,Wang, Yun-Zhao
-
p. 9872 - 9878
(2020/06/27)
-
- Preparation method of thermal paper sensitizer benzyl-2-naphthyl ether
-
The invention relates to a preparation method of a thermal paper sensitizer benzyl-2-naphthyl ether. According to the preparation method, benzyl alcohol and 2-bromonaphthalene are used as raw materials, N-tetrahydropyrrole acetic acid is used as a ligand, and Cu (I) or Cu (II) is used as a catalyst in the presence of alkali and a solvent to prepare benzyl-2-naphthyl ether. The preparation method comprises the steps of S1, uniformly mixing and stirring 2-bromonaphthalene and a certain quantity of the solvent, and then sequentially adding a certain quantity of alkalis, the catalyst, the ligand and benzyl alcohol; S2, controlling the reaction temperature and time and stirring the reactants during a reaction; S3, after the reaction is finished, recovering the solvent, adding a certain amount of water and an organic solvent, extracting a water phase with the organic solvent several times, combining organic phases, and sequentially performing washing with water and a sodium carbonate water solution; S4, performing drying, filtering, decolorizing and distilling on the combined organic phase after washing is finished to obtain a crude product, and recrystallizing and drying the crude product to obtain a finished product. According to the method, the production cost is greatly reduced after benzyl alcohol and 2-bromonaphthalene are used as the reaction raw materials, and the method hasa high implementation value and great social and economic benefits.
- -
-
Paragraph 0026-0046
(2019/10/02)
-
- Gold(i)-catalyzed Nicholas reaction with aromatic molecules utilizing a bifunctional propargyl dicobalt hexacarbonyl complex
-
A benchtop-stable reagent for the catalytic Nicholas reaction was developed. By combining a propargyl dicobalt hexacarbonyl cluster with an ortho-alkynylbenzoate unit and a fluorous tag, introduction of a propargyl hexacarbonyl complex on various aromatic compounds having acid- or base-sensitive functional groups becomes possible by using a gold(i) catalyst. In addition, the presence of a fluorous tag facilitates convenient separation of the target products from byproducts.
- Okamura, Toshitaka,Fujiki, Shogo,Iwabuchi, Yoshiharu,Kanoh, Naoki
-
supporting information
p. 8522 - 8526
(2019/10/02)
-
- Iodine(III)-Mediated, Controlled Di- or Monoiodination of Phenols
-
An oxidative procedure for the electrophilic iodination of phenols was developed by using iodosylbenzene as a nontoxic iodine(III)-based oxidant and ammonium iodide as a cheap iodine atom source. A totally controlled monoiodination was achieved by buffering the reaction medium with K3PO4. This protocol proceeds with short reaction times, at mild temperatures, in an open flask, and generally with high yields. Gram-scale reactions, as well as the scope of this protocol, were explored with electron-rich and electron-poor phenols as well as heterocycles. Quantum chemistry calculations revealed PhII(OH)·NH3 to be the most plausible iodinating active species as a reactive "I+" synthon. In light of the relevance of the iodoarene moiety, we present herein a practical, efficient, and simple procedure with a broad functional group scope that allows access to the iodoarene core unit.
- Satkar, Yuvraj,Yera-Ledesma, Luisa F.,Mali, Narendra,Patil, Dipak,Segura-Quezada, Luis A.,Ramírez-Morales, Perla I.,Solorio-Alvarado, César R.,Navarro-Santos, Pedro
-
p. 4149 - 4164
(2019/04/30)
-
- Electrochemical C-H cyanation of electron-rich (Hetero)arenes
-
A straightforward method for the electrochemical C-H cyanation of arenes and heteroarenes that proceeds at room temperature in MeOH, with NaCN as the reagent in a simple, open, undivided electrochemical cell is reported. The platinum electrodes are passivated by ad-sorbed cyanide, which allows conversion of an exceptionally broad range of electron-rich substrates all the way down to dialkyl arenes. The cyanide electrolyte can be replenished with HCN, opening opportunities for salt-free industrial C-H cyanation.
- Hayrapetyan, Davit,Rit, Raja K.,Kratz, Markus,Tschulik, Kristina,Goo?en, Lukas J.
-
supporting information
p. 11288 - 11291
(2018/10/20)
-
- Hydrodehalogenation of Haloarenes by a Sodium Hydride–Iodide Composite
-
A simple protocol for hydrodebromination and -deiodination of halo(hetero)arenes was enabled by sodium hydride (NaH) in the presence of lithium iodide (LiI). Mechanistic studies showed that an unusual concerted nucleophilic aromatic substitution operates in the present process.
- Ong, Derek Yiren,Tejo, Ciputra,Xu, Kai,Hirao, Hajime,Chiba, Shunsuke
-
supporting information
p. 1840 - 1844
(2017/02/05)
-
- Exploring the Reactivity of α-Lithiated Aryl Benzyl Ethers: Inhibition of the [1,2]-Wittig Rearrangement and the Mechanistic Proposal Revisited
-
By carefully controlling the reaction temperature, treatment of aryl benzyl ethers with tBuLi selectively leads to α-lithiation, generating stable organolithiums that can be directly trapped with a variety of selected electrophiles, before they can undergo the expected [1,2]-Wittig rearrangement. This rearrangement has been deeply studied, both experimentally and computationally, with aryl α-lithiated benzyl ethers bearing different substituents at the aryl ring. The obtained results support the competence of a concerted anionic intramolecular addition/elimination sequence and a radical dissociation/recombination sequence for explaining the tendency of migration for aryl groups. The more favored rearrangements are found for substrates with electron-poor aryl groups that favor the anionic pathway.
- Velasco, Rocío,Silva López, Carlos,Nieto Faza, Olalla,Sanz, Roberto
-
supporting information
p. 15058 - 15068
(2016/10/11)
-
- Choline chloride based deep eutectic solvent as an efficient solvent for the benzylation of phenols
-
Deep eutectic solvents (such as the combination of urea and choline chloride) are found to be promising solvent and phase-transfer-media for benzylation of phenol. These methods avoided the complexity of multiple alkylations giving selectively O-alkylated aromatic products. Good to excellent yields of the corresponding benzyl phenyl ether were obtained. The non-toxic, biodegradable, inexpensive, and recyclable nature of DES make this protocol green and cost-effective.
- Singh, Abhilash S.,Shendage, Suresh S.,Nagarkar, Jayashree M.
-
p. 7243 - 7246
(2015/02/02)
-
- Tetrabutyl ammonium bromide-mediated benzylation of phenols in water under mild condition
-
Benzylation of phenol was successfully achieved in water under room temperature mediated by tetrabutylammonium bromide (TBAB) for only 2 h affording the corresponding benzyl phenyl ether with good to excellent yields. This protocol is very efficient, simple, avoiding catalysts, easy to work-up after reaction, and especially 'green'.
- Wang, Hailei,Ma, Yuping,Tian, Heng,Yu, Ajuan,Chang, Junbiao,Wu, Yangjie
-
p. 2669 - 2673
(2014/04/03)
-
- Microwave-Assisted solid-liquid phase alkylation of naphthols
-
The microwave promoted alkylation of 1- and 2-naphthols with benzyl, butyl, ethyl and isopropyl halides in the presence of an alkali carbonate may result in O- and C-Alkylated products. The alkylations were O-selective in the presence of K2CO3 in acetonitrile as the solvent and in the absence of phase transfer catalyst. The alkylations utilizing butyl and ethyl halides were also O-selective in solventless accomplishment and in the presence of triethylbenzylammonium chloride.
- Balint, Erika,Kovacs, Orsolya,Drahos, Laszlo,Keglevich, Gyoergy
-
p. 330 - 336
(2013/07/26)
-
- TRIAMINOCYCLOPROPENIUM SALTS
-
Disclosed are salts comprising triaminocyclopropenium cations and various anions, and ionic liquids comprising the salts. Also disclosed are intermediates and methods of preparing the salts. The ionic liquids are useful as, for example, solvents and electrolytes, and for gas storage.
- -
-
Page/Page column 166
(2013/02/27)
-
- Triaminocyclopropenium salts as ionic liquids
-
Salts of the charge-delocalised cations of the triaminocyclopropenium (tac) family bearing alkyl substituents have been prepared and shown to be air- and water-stable ionic liquids.
- Curnow, Owen J.,MacFarlane, Douglas R.,Walst, Kelvin J.
-
supporting information; experimental part
p. 10248 - 10250
(2011/10/18)
-
- Synthesis of aryl alkyl ethers by alkylation of phenols with quaternary ammonium salts
-
Phenolic compounds can be efficiently O-methylated with tetramethylammonium chloride in diglyme or polyethyleneglycol (PEG) at temperatures of 150-160 °C and in the presence of either K2CO3 or NaOH. When applying benzyl-trimethylammonium chloride as a reagent, the benzylation and methylation of phenols occurs, with the benzylation product always predominating. With allyl-substituted phenols as substrates and using NaOH as a base it was possible to achieve both the alkylation and the double-bond isomerization of the allyl group to obtain (E/Z)-propenyl-substituted methyl and benzyl aryl ethers in a single preparative step.
- Maras, Nenad,Polanc, Slovenko,Kocevar, Marijan
-
experimental part
p. 29 - 36
(2010/09/05)
-
- Palladium complexes with abnormal N-heterocyclic carbene ligands derived from 1,2,3-triazolium ions and their application in Suzuki coupling
-
Chiral and achiral pincer type palladium complexes bearing abnormal N-heterocyclic carbene ligands derived from 1,2,3-triazole are reported. Both complexes are effective as catalysts for non-asymmetric Suzuki coupling reaction for the synthesis of bipheny
- Karthikeyan, Thandavamurthy,Sankararaman, Sethuraman
-
scheme or table
p. 5834 - 5837
(2010/01/11)
-
- Microwave-assisted synthesis of substituted phenanthrenes, anthracenes, acenaphthenes, and fluorenes
-
Rapid coupling reactions of polycyclic aromatic halides with various N-, S-, and Se-nucleophiles under focused microwave irradiation are described. Using this method, the desired products are obtained with good to excellent yields in a short reaction time. Crown Copyright
- Chan, Shiuh-Chuan,Jang, Jing-Pei,Cherng, Yie-Jia
-
experimental part
p. 1977 - 1981
(2009/08/08)
-
- Counterattack mode differential acetylative deprotection of phenylmethyl ethers: Applications to solid phase organic reactions
-
A counterattack protocol for differential acetylative cleavage of phenylmethyl ether has been developed. The phenylmethyl moiety is liberated as benzyl bromide that is isolated and reused providing advantages in terms of waste minimization/utilization and atom economy. The applicability of this methodology has been extended for solid phase organic reactions with the feasibility of reuse of the solid support.
- Chakraborti, Asit K.,Chankeshwara, Sunay V.
-
supporting information; experimental part
p. 1367 - 1370
(2009/07/04)
-
- Organic pollutants in paper-recycling process water discharge areas: First detection and emission in aquatic environment
-
In this study, eight compounds have been identified and quantified from the samples collected from paper-recycling process water discharge areas. In particular, five aryl hydrocarbons, including a novel chlorinated aryl ether, were identified for the first time as environmental pollutants. In the effluent stream, concentration levels of up to 1600 μg L-1 and 190 μg g-1 were detected in the surface water and surface sediment, respectively. The results of this study have raised concerns regarding the organic chemicals used in thermal paper and the environmental consequences of their release.
- Terasaki, Masanori,Fukazawa, Hitoshi,Tani, Yukinori,Makino, Masakazu
-
-
- Heterogeneous catalysis with nickel-on-graphite (Ni/Cg): Reduction of aryl tosylates and mesylates
-
(Chemical Equation Presented) How would you reduce an aryl OH group? Traditionally, a palladium catalyst, a mild source of hydride, and a triflate derivative are used in solution. A more modern alternative is presented that is not only economical but heterogeneous as well. Nickel-on-graphite (Ni/C g) is introduced as a very inexpensive catalyst that reduces aryl tosylates and mesylates with excellent functional group tolerance.
- Lipshutz, Bruce H.,Frieman, Bryan A.,Butler, Tom,Kogan, Vladimir
-
p. 800 - 803
(2007/10/03)
-
- Williamson reaction in [bmim][BF4]: Clean and facile synthesis of aryl benzyl ethers
-
1-Butyl-3-methylimidazolium tetrafluoroborate ([bmin][BF4]) has been demonstrated to be a suitable reaction medium for the synthesis of aryl benzyl ethers by the Williamson reaction. A variety of phenols react with benzyl chloride in [bmim][BF4] to afford the desired ethers in satisfactory yields. The reaction proceeds cleanly and the use of the ionic liquid allows for easy product isolation.
- Wen, Xinmin
-
p. 663 - 664
(2007/10/03)
-
- Applications of surfactant-modified clays to synthetic organic chemistry
-
Two triphase catalysts (SLL) have been developed for organic phase-aqueous phase reactions catalyzed by suitable modified clay (solid phase). These triphase catalysts have been applied to nucleophilic displacement on activated (benzylic) as well as unactivated organic halides and provide a convenient and effective method of preparation of the corresponding products. Other useful transformations to, which these triphase catalysts have been successfully applied are the synthesis of 9,9-dichloro bicyclo[6.1.0]nonane, O-alkylation and C-alkylation of β-naphthol.
- Ghiaci,Sedaghat,Kalbasi,Abbaspur
-
p. 5529 - 5534
(2007/10/03)
-
- Efficient methods for the preparation of alkyl-aryl and symmetrical or unsymmetrical dialkyl ethers between alcohols and phenols or two alcohols by oxidation-reduction condensation
-
Oxidation-reduction condensation via alkoxydiphenylphosphines (diphenylphosphinite esters) (1), generated in situ from chlorodiphenylphosphine (2) and alcohols, 2,6-dimethyl-1,4-benzoquinone (3), and phenols proceeds smoothly to afford alkyl-aryl ethers in good to high yields under neutral conditions. In a similar fashion, a new and efficient method for the preparation of symmetrical or unsymmetrical dialkyl ethers in good to high yields is established via tetrafluoro-1,4-benzoquinone (fluoranil) (4), alcohols, and 1 formed in situ from nBuLi-treated alcohols and 2. This method is applicable also to the etherification of chiral secondary or tertiary alcohols with retention or inversion of configurations. The inverted ethers are afforded by treating chiral alkoxydiphenylphosphines and achiral alcohols, while the reaction of achiral alkoxydiphenylphosphines and chiral alcohols forms retained ethers.
- Shintou, Taichi,Mukaiyama, Teruaki
-
p. 7359 - 7367
(2007/10/03)
-
- Synergism of low energy microwave irradiation and solid-liquid phase transfer catalysis for selective alkylation of phenols to phenolic ethers
-
A 100% selectivity with an order of magnitude rate enhancement is obtained in the synthesis of phenolic ethers when synergistic combination of solid-liquid phase transfer catalysis and low energy microwave irradiation (MISL-PTC) is employed. As against conventional microwave heating with 600 W power input, the current work demonstrates that a low input of 40 W leads to remarkable enhancement in rates without any destruction of the catalyst.
- Yadav, Ganapati D.,Bisht, Priyal M.
-
p. 2885 - 2892
(2007/10/03)
-
- Zinc-catalyzed Williamson ether synthesis in the absence of base
-
A zinc-catalyzed Williamson ether synthesis is described with microwave heating in the presence of DMF or stirring in an oil-bath using THF as solvent and in the absence of base. Zinc powder was found to be a highly efficient catalyst for the synthesis of aromatic ethers using microwave heating in the presence of N,N-dimethylformamide as well as under stirring in an oil-bath using tetrahydrofuran as solvent without any inorganic base. This method can be used for selective mono-, di- or tri-O-alkylations.
- Paul, Satya,Gupta, Monika
-
p. 8825 - 8829
(2007/10/03)
-
- Alkylation of phenols by oxidation-reduction condensation using 2,6-dimethyl-1,4-benzoquinone and alkoxydiphenylphosphine
-
Various alkyl phenyl ethers were obtained in high yields by way of oxidation-reduction condensation where alkoxydiphenylphosphine, prepared easily from chlorodiphenylphosphine and corresponding alcohols, was treated with various phenols in the co-existenc
- Shintou, Taichi,Kikuchi, Wataru,Mukaiyama, Teruaki
-
-
- Efficient method for the preparation of carboxylic acid alkyl esters or alkyl phenyl ethers by a new-type of oxidation-reduction condensation using 2,6-dimethyl-1,4-benzoquinone and alkoxydiphenylphosphines
-
A new-type of oxidation-reduction condensation proceeded smoothly to afford carboxylic acid alkyl esters or alkyl phenyl ethers in good to high yields by combined use of alkoxydiphenylphosphines (1) having primary, bulky secondary or tertiary alkoxy groups, a mild quinone-type oxidant such as 2,6-dimethyl-1,4-benzoquinone (DMBQ) and carboxylic acids or phenols. Generally, alkoxydiphenylphosphines were prepared easily from chlorodiphenylphosphine (2) and alcohols in the presence of pyridine, and were isolated by distillation. On the other hand, the phosphines 1 were also prepared in situ from N,N-dimethylaminodiphenylphosphine (3a) and primary or secondary alcohols while primary, bulky secondary or tertiary alkoxydiphenylphosphines were alternatively formed in situ by adding 2 to the "BuLi-treated alcohols in order to perform the above reactions by a one-pot procedure from alcohols and nucleophiles. The reaction of thus formed 1, DMBQ and carboxylic acids or phenols afforded the corresponding alkylated products, including hindered secondary and tertiary alkylated ones, in good to high yields at room temperature. In the case of using chiral secondary alcohols, the corresponding carboxylic acid alkyl esters were obtained as well in high yields with perfect inversion of stereochemistry by SN2 replacement.
- Shintou, Taichi,Kikuchi, Wataru,Mukaiyama, Teruaki
-
p. 1645 - 1667
(2007/10/03)
-
- Systematic ranking of nucleophiles as electron donors
-
A systematic ranking of different nucleophiles (including enolates, phenolates, thiophenolates, hydroxide, cyanide) with respect to their ability to stabilise the transition state of substitution reactions has been carried out in acetonitrile and dimethyl sulfoxide. The method is based on a comparison of the rate constant, kSUB, for the substitution reaction between a given nucleophile and benzyl chloride with the rate constant, kET, for the corresponding electron transfer from an aromatic radical anion to benzyl chloride. The ratio kSUB/kET expresses the rate enhancement due to electronic interaction in the transition state, ΔGSta, of the substitution reaction. In this study, kSUB/kET ratios between 5 and 1031 were determined corresponding to ΔGSta-values of 4-175 kJ mol-1. These values cover substitution reactions going from outer-sphere electron transfer to SN2 with partial bond formation in the transition state. The kSUB/kET values are found to be largest for nucleophiles such as OH- and CN- with very poor electron-donating abilities (high oxidation potentials). When different types of nucleophile with similar oxidation potentials are compared, a decrease in kSUB/kET is observed going from sulfur-to carbon- and further to oxygen-centred nucleophiles. The ranking of nucleophiles in reactions involving electrophiles other than benzyl chloride is discussed with emphasis on steric hindrance and electronic effects.
- Daasbjerg, Kim,Knudsen, Stig R.,Sonnichsen, Katrine N.,Andrade, Adalgisa R.,Pedersen, Steen U.
-
p. 938 - 948
(2007/10/03)
-
- Solid composite copper-copper chloride assisted alkylation of naphthols promoted by microwave irradiation
-
Naphthyl ethers and naphthyl esters were synthesized in good yield by using mixture of copper metal powder and copper (II) chloride in conventional microwave oven in short time.
- Zadmard,Aghapoor,Bolourtchian,Saidi
-
p. 4495 - 4499
(2007/10/03)
-
- Regioselective alkylation in ionic liquids
-
The room temperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate, [bmim][PF6], is used as a 'green' recyclable alternative to dipolar aprotic solvents for the regioselective alkylation at the heteroatom of indole and 2-naphthol.
- Earle, Martyn J.,McCormac, Paul B.,Seddon, Kenneth R.
-
p. 2245 - 2246
(2007/10/03)
-
- Highly Efficient and Convenient Methods for the Direct Conversion of Aryl Silyl Ethers and Aryl Acetates into Aryl Alkyl Ethers
-
Direct conversion of aryl trialkylsilyl ethers and aryl acetates into the corresponding alkyl-protected phenols such as benzyl and allyl ethers can be conveniently performed by the reaction with alkyl halide in the presence of cesium fluoride and sodium methoxide, respectively, in a one-pot procedure.
- Oriyama, Takeshi,Noda, Kojiro,Yatabe, Kaori
-
p. 701 - 703
(2007/10/03)
-
- Oxidation potential as a measure of the reactivity of anionic nucleophiles. Behaviour of different classes of nucleophiles
-
Anodic peak potentials for 42 anionic nucleophiles are reported along with the rate constants for the reactions of the anions with benzyl chloride.By comparing these rate constants with those of the reactions of outer-sphere electron-transfer reagents (radical anions), it has been demonstrated that the reactions of the anions with benzyl chloride are typical single-step SN2 reactions as opposed to a two-step process comprising dissociative single electron transfer (SET) to benzyl chloride followed by radical combination.The data suggest that very electron-rich nucleophilic anions with potentials of -1.5 to -2.2 V (and more negative) with respect to the ferrocenium/ferrocene couple might participate in a SET reaction.The 42 anions studied included representatives of four classes of nucleophiles, viz. sulfur-, carbon-, oxygen- and nitrogen-centred anions.The previously observed correlation of rate constants and anodic peak potential was again found for these anions with the most reactive species having the most negative peak potentials.Correlations by class indicate that the sensitivity of rate constants to changes in peak potential is greatest (and equivalent) for the sulfur-, carbon- and oxygen-anions and for representatives with the same peak potential, the rate constants by class follow the order sulfur > carbon > oxygen.The nitrogen nucleophiles show a significantly lower sensitivity of rate constant to changes in peak potential than do the other three classes.
- Niyazymbetov, Murat E.,Rongfeng, Zhou,Evans, Dennis H.
-
p. 1957 - 1962
(2007/10/03)
-
- Influence of phase transfer catalyst structure on selectivity
-
A concise review is given of systematic studies concerned with the tuning of regio-, "frequentio-", chemo-, and diastereoselectivity by the structure or type of phase transfer catalyst. - Keywords: phase transfer catalysis; regioselectivity; selectivity control; stereoselectivity; C/O-alkylation; C/N-alkylation.
- Dehmlow, E. V.
-
p. 1998 - 2005
(2007/10/03)
-
- Facile synthesis of alkyl phenyl ethers using cesium carbonate
-
A highly efficient alkylation method of phenols using alkyl halide/cesium carbonate/acetonitrile system is described.
- Lee,Yuk,Cho
-
p. 1367 - 1370
(2007/10/02)
-
- Preparation of β-naphthyl benzyl ether
-
A process for preparing β-naphthyl benzyl ether comprises reacting β-naphthol essentially in the absence of water with an alkali metal carbonate or an alkaline earth metal carbonate and benzyl chloride in an inert water-miscible solvent at from 0° to 200° C.
- -
-
-
- Photoamination of 2-Alkoxynaphthalenes with Alkylamines via Electron Transfer and Its Application to Synthesis of 1-Alkylamino-2-tetralones
-
Photoamination of 2-alkoxynaphthalenes (1) with ammonia and primary alkylamines were performed by irradiating an acetonitrile-water solution containing 1, an amine, and m-dicyanobenzene to give 1-alkylamino-2-alkoxy-1,4-dihydronaphthalene (2) in relatively good yields.The conversion of 2 to N-acetyl-1-alkylamino-2-tetralones was performed by acetylation with Ac2O by a treatment with BF3*OEt2.
- Yamashita, Toshiaki,Tanabe, Kimiko,Yamano, Katsuhiko,Yasuda, Masahide,Shima, Kensuke
-
p. 246 - 250
(2007/10/02)
-
- Ionic liquids as solvents for the regioselective O-alkylation of C/O ambident nucleophiles
-
The reaction of sodium β-naphthoxide with benzyl halides in molten tetraalkylammonium or phosphonium halides (at 110°C or below) leads to a highly regioselective O-alkylation. These new solvents, which can be quantitatively recovered at the end of the reaction, mimic the behaviour of dipolar aprotic solvents.
- Badri, Meryam
-
p. 4435 - 4438
(2007/10/02)
-
- Ameliorations et simplification de la synthese des ethers phenoliques par alkylation d'ions phenates: catalyse par transfert de phase solide-liquide sans solvant
-
Several aryl ethers can be obtained in excellent yields under mild and economical conditions in the absence of organic solvents by reacting stoechiometric amounts of corresponding phenol, finely ground KOH and alkyl bromides in the presence of 2percent Aliquat 336.This method is very favourable compared with recent works dealing with anionic activation.
- Loupy, Andre,Sansoulet, Jean,Zand, Farchid Vaziri-
-
p. 1027 - 1035
(2007/10/02)
-
- Electron Apportionment in Cleavage of Radical Anions. 2. Naphthylmethyl Phenyl Ethers vs. Naphthyl Benzyl Ethers
-
Naphthylmethyl phenyl ethers and naphthyl benzyl ethers were found to undergo scission of the H2C-O bond when treated with radical anions of anthracene or fluoranthene.Under comparable conditions, ethers of the naphthylmethyl phenyl series (α and β) reacted more than 10E4 times faster than ethers of the naphthyl benzyl series (α and β).This preference for regioconservation of spin density in the scission process is interpreted in terms of ?-bond polarization at the transition state.
- Maslak, Przemyslaw,Guthrie, Robert D.
-
p. 2637 - 2640
(2007/10/02)
-
- HIGHLY SELECTIVE BENZILATIONS OF β-NAPHTHOXIDE ANION IN HETEROGENEOUS MEDIA
-
Each of the four products resulting from the benzylation of the ambident β-naphthoxide anion can be efficiently and selectively obtained in mild an economical conditions by a judicious choice of the solid base: LiOH, LiOtBu or KOH-Aliquat.
- Bram, G.,Loupy, A.,Sansoulet, J.,Vaziri-Zand, F
-
p. 5035 - 5038
(2007/10/02)
-
- THE ROLE HYDROGEN BONDING IN THE AUTOOXIDATION AND ALKYLATION OF 2-NAPHTHOLS
-
The powerful hydrogen bond electron donor fluoride ion assists the O-alkylation of 2-naphthols but inhibits the autooxidation of 1-alkyl-2-naphthols.These observations may be explained in terms of the nature of the OHF- hydrogen bond.
- Jazzaa, Abdulaziz Al,Clark, James H.,Miller, Jack M.
-
-
- Kinetics of Benzylation of Hydroxypyridines & Hydroxyquinolines in Dimethyl Sulphoxide - Water & Isopropanol - Water Mixtures
-
The kinetics of benzylation of hydroxypyridines and hydroxyquinolines have been investigated in DMSO-water and isopropanol-water mixtures.A formal comparison of rate of benzylation of phenols and naphthols has also been made.DMSO, being a dipolar aprotic solvent facilitates O-alkylation of phenols and naphthols and a considerable rate increase has been observed in DMSO-water, giving the O-alkylated products in more than 90percent yield in both the cases.However, in the case of benzylation of hydroxypyridine in DMSO-water, O-alkylated product formed is only 65percent and the magnitude of rate increase, compared to phenols and naphthols, is much less, under similar conditions.But the rate of benzylation of 8-hydroxyquinoline in DMSO-water is retarded considerably and the rate is even slower than the rate of N-benzylation of quinoline, indicating only O-benzylation of 8-hydroxyquinoline in DMSO-water is unique and is mainly due to greater ground state solvation of substrate by DMSO, a factor which has been considered insignificant in all the other cases.
- Rajasekar, N.,Srinivasan, V. S.,Venkatasubramanian, N.
-
p. 800 - 802
(2007/10/02)
-
- A Simple One-step Synthesis of Phenyl Ethers from Phenyl Acetates
-
Phenyl acetates when refluxed with alkyl halides in acetone solution in the presence of a crown ether and anhydrous potassium carbonate undergo alkylation yielding phenyl ethers.
- Banerjee, Sunil K.,Gupta, Bishan D.,Singh, Kuber
-
p. 815 - 816
(2007/10/02)
-
- Regioselectivity of the Alkylation of Ambident Anionic Species on Alumina or in the Presence of 'Solid Hexamethylphosphoric Triamide'
-
C-Alkylation of the acetoacetate anions and of sodium naphthoxide is highly favoured on alumina, while O-alkylation of the acetoacetate anion predominates in tetrahydrofuran in the presence of solid hexamethylphosphoric triamide.
- Bram, Georges,Geraghty, Niall,Nee, Gerard,Seyden-Penne, Jacqueline
-
p. 325 - 326
(2007/10/02)
-