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OPTIMIZATION OF POLYMER-SUPPORTED OLIGOETHERS AS SOLID-LIQUID PHASE TRANSFER CATALYSTS
Oligoether residues with terminal 8-quinolyl donor groups have been loaded virtually quantitatively onto polystyrene resin supports and function more effectively than dibenzo-18-crown-6 as solid/liquid phase transfer catalysts in Williamson ether syntheses.
Heffernan, J.G.,Sherrington, D.C.
p. 1661 - 1664
(1983)
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Non-supported and Resin-supported Oligo(oxyethylenes) as Solid-Liquid Phase-transfer Catalysts. Effect of Chain Length and Head-group
A series of oligo(oxyethylenes) containing 3-30 ethylene oxide residues and a number of polystyrene resin-supported analogues have been examined as phase-transfer catalysts in the reaction of solid potassium phenoxide with 1-bromobutane in toluene.With both groups of catalysts the activity increases with the length of the oligoether chain.This effect arises despite a fall in the ability of the oligoethers to solubilize the phenoxide, and must therefore be associated with an increase in the nucleophilicity of the phenoxide anion in the oligoether complexed ion pairs.A group of oligo(oxyethylenes) with three ethylene oxide residues and symmetrically substituted with different head-groups was also examined.One with 8-quinolyl end-groups proved to be as active as dibenzo-18-crown-6, whereas, somewhat surprisingly, a corresponding species with 2-methoxyphenyl substituents was a relatively poor catalyst.In this case the geometry of complexation might allow retention of intimate ion pair character.In the case of oligoethers with head-groups OH,OH; OH,OCH3; and OCH3,OCH3 the presence of an hydroxy-group appears to enhance the ability to complex K+, but simultaneously reduces catalytic activity, possibly because of interaction with the phenoxide counterion.As a result, the unsymmetrically substituted derivative is the most active catalyst providing an optimum balance of these factors.Two series of resin-supported analogues, one with three ethylene oxide residues in each oligoether chain and one with four, were also synthesised.In each case the derivative with an 8-quinolyl head-group and one related structure derived from 2-pyridylmethanol were the most active catalysts.Again the two species with a 2-methoxyphenyl head-group were less effective than anticipated.In the case of the oligoether chain with four ethylene oxide residues, the activity was somewhat better and there is some correlation with the reported complexing ability of analogous unbound species.
Heffernan, James G.,MacKenzie, William M.,Sherrington, David C.
p. 514 - 517
(1981)
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Stealth star polymers: A new high-loading scaffold for liquid-phase organic synthesis
(formula presented) Polyethylene glycol (PEG) has proven to be a versatile soluble-polymer support for organic synthesis, though the use of PEG has been limited by its relatively low loading (0.5 mmol/g or less). We have developed a new high-loading (1 mmol/g) soluble-star polymer based on a cyclotriphosphazene core with PEG arms that exhibit superior precipitation properties compared with those of linear PEG. Additionally, the heterocyclic core does not add interfering signals to the 1H or 13C NMR.
Reed, Neal N.,Janda, Kim D.
p. 1311 - 1313
(2000)
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Magnetically separable phase-transfer catalysts
Magnetic nanoparticles-supported quaternary ammonium and phosphonium salts were prepared and evaluated as phase-transfer catalysts. Some of them exhibited good activities that were comparable to that of tetra-n-butylammonium iodide. The catalysts were readily separated using an external magnet and reusable without significant loss of their catalytic efficiency. The Royal Society of Chemistry.
Kawamura, Masato,Sato, Kazuhiko
p. 4718 - 4719
(2006)
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Use of diethoxymethane as a solvent for phase transfer-catalyzed O -alkylation of phenols
The effectiveness of diethoxymethane (DEM) as a solvent for O-alkylation of a variety of phenols under phase transfer conditions has been examined and evaluated. The reaction between 4-methoxy phenol and benzyl chloride was selected to compare reaction rates in various solvents and the efficiency of various PTCs. This reaction was further studied to develop a commercially amenable process complete with recycle streams and efficient product isolation. DEM is a good solvent for these types of phase transfer-catalyzed reactions and can be considered as an alternative solvent for dichloromethane and toluene.
Coleman, M. Todd,Leblanc, Gabriel
p. 732 - 736
(2010)
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Approximate rate constants for intermolecular additions of alkyl radicals to phenylsulfonyl oxime ethers
Approximate rate constants for intermolecular additions of alkyl radicals to phenylsulfonyl oxime ethers (2a and 2b) have been determined to be k(a) = 9.6 x 105 M-1 s-1 at 25°C for 2a and k(a) = 7.3 x 104 M-1 s-1 at 60°C for 2b, indicating that the additions are fast and highly efficient processes. The kinetic data have been confirmed by two competition experiments.
Kim, Sunggak,Lee, Ill Young
p. 1587 - 1590
(1998)
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N-ARYL SULFONAMIDE DERIVATIVES AS VACCINE ADJUVANT
Bis-aryl sulfonamide compounds and methods of using those compounds, e.g., in a method of enhancing or prolonging an immune response, are provided. For example, the compounds may be employed with a vaccine and optionally at least one other adjuvant and/or one or more TLR ligands, at least one MAP kinase inhibitor, or any combination thereof.
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Page/Page column 101-102

(2021/02/26)

Methylation with Dimethyl Carbonate/Dimethyl Sulfide Mixtures: An Integrated Process without Addition of Acid/Base and Formation of Residual Salts
Dimethyl sulfide, a major byproduct of the Kraft pulping process, was used as an inexpensive and sustainable catalyst/co-reagent (methyl donor) for various methylations with dimethyl carbonate (as both reagent and solvent), which afforded excellent yields of O-methylated phenols and benzoic acids, and mono-C-methylated arylacetonitriles. Furthermore, these products could be isolated using a remarkably straightforward workup and purification procedure, realized by dimethyl sulfide‘s neutral and distillable nature and the absence of residual salts. The likely mechanisms of these methylations were elucidated using experimental and theoretical methods, which revealed that the key step involves the generation of a highly reactive trimethylsulfonium methylcarbonate intermediate. The phenol methylation process represents a rare example of a Williamson-type reaction that occurs without the addition of a Br?nsted base.
Chan, Bun,Lui, Matthew Y.,Lui, Yuen Wai
(2022/01/08)

Radical Anion Promoted Chemoselective Cleavage of Csp2-S Bond Enables Formal Cross-Coupling of Aryl Methyl Sulfones with Alcohols
A novel formal cross-coupling of aryl methyl sulfones and alcohols affording alkyl aryl ethers via an SRN1 pathway is developed. Two marketed antitubercular drugs were efficiently prepared employing this approach as the key step. A dimsyl-anion initiated radical chain process was revealed as the major pathway. DFT calculations indicate that the formation of a radical anion via nucleophilic addition of alkoxide to the aryl radical is the key step in determining the observed chemoselectivity.
Bai, Jixiang,Wang, Tianxin,Dai, Botao,Liu, Qingchao,Yu, Peiyuan,Jia, Tiezheng
supporting information
p. 5761 - 5765
(2021/08/16)

Light-Promoted Nickel Catalysis: Etherification of Aryl Electrophiles with Alcohols Catalyzed by a NiII-Aryl Complex
A highly effective C?O coupling reaction of (hetero)aryl electrophiles with primary and secondary alcohols is reported. Catalyzed by a NiII-aryl complex under long-wave UV (390–395 nm) irradiation in the presence of a soluble amine base without any additional photosensitizer, the reaction enables the etherification of aryl bromides and aryl chlorides as well as sulfonates with a wide range of primary and secondary aliphatic alcohols, affording synthetically important ethers. Intramolecular C?O coupling is also possible. The reaction appears to proceed via a NiI–NiIII catalytic cycle.
Cao, Rui,Lai, Chu-Hui,Li, Gang,Liu, Fengyi,Lu, Huan-Huan,Wang, Chao,Xiao, Jianliang,Xue, Dong,Yang, Liu,Zhang, Wei
supporting information
p. 12714 - 12719
(2020/06/02)

CoII Immobilized on Aminated Magnetic-Based Metal–Organic Framework: An Efficient Heterogeneous Nanostructured Catalyst for the C–O Cross-Coupling Reaction in Solvent-Free Conditions
Abstract: In this paper, we report the synthesis of Fe3O4?AMCA-MIL53(Al)-NH2-CoII NPs based on the metal–organic framework structures as a magnetically separable and environmentally friendly heterogeneous nanocatalyst. The prepared nanostructured catalyst efficiently promotes the C–O cross-coupling reaction in solvent-free conditions without the need for using toxic solvents and/or expensive palladium catalyst. Graphic Abstract: [Figure not available: see fulltext.].
Mohammadinezhad, Arezou,Akhlaghinia, Batool
p. 332 - 352
(2020/01/11)

Nickel-catalyzed removal of alkene protecting group of phenols, alcohols via chain walking process
An efficient nickel-catalyzed removal of alkene protection group under mild condition with high functional group tolerance through chain walking process has been established. Not only phenolic ethers, but also alcoholic ethers can be tolerated with the retention of stereocenter adjacent to hydroxyl group. The new reaction brings the homoallyl group into a start of new type of protecting group.
Meng, Chenkai,Niu, Haolin,Ning, Juehan,Wu, Wengang,Yi, Jun
(2020/02/04)

Structure-Activity Relationship Studies to Identify Affinity Probes in Bis-aryl Sulfonamides That Prolong Immune Stimuli
Agents that safely induce, enhance, or sustain multiple innate immune signaling pathways could be developed as potent vaccine adjuvants or coadjuvants. Using high-throughput screens with cell-based nuclear factor κB (NF-κB) and interferon stimulating response element (ISRE) reporter assays, we identified a bis-aryl sulfonamide bearing compound 1 that demonstrated sustained NF-κB and ISRE activation after a primary stimulus with lipopolysaccharide or interferon-α, respectively. Here, we present systematic structure-activity relationship (SAR) studies on the two phenyl rings and amide nitrogen of the sulfonamide group of compound 1 focused toward identification of affinity probes. The murine vaccination studies showed that compounds 1 and 33 when used as coadjuvants with monophosphoryl lipid A (MPLA) showed significant enhancement in antigen ovalbumin-specific immunoglobulin responses compared to MPLA alone. SAR studies pointed to the sites on the scaffold that can tolerate the introduction of aryl azide, biotin, and fluorescent rhodamine substituents to obtain several affinity and photoaffinity probes which will be utilized in concert for future target identification and mechanism of action studies.
Chan, Michael,Lao, Fitzgerald S.,Chu, Paul J.,Shpigelman, Jonathan,Yao, Shiyin,Nan, Jason,Sato-Kaneko, Fumi,Li, Vicky,Hayashi, Tomoko,Corr, Maripat,Carson, Dennis A.,Cottam, Howard B.,Shukla, Nikunj M.
supporting information
p. 9521 - 9540
(2019/11/11)

Reductive C-O, C-N, and C-S Cleavage by a Zirconium Catalyzed Hydrometalation/β-Elimination Approach
A zirconium catalyzed reductive cleavage of Csp3 and Csp2 carbon-heteroatom bonds is reported that makes use of a tethered alkene functionality as a traceless directing group. The reaction is successfully demonstrated on C-O, C-N, and C-S bonds and proposed to proceed via a hydrozirconation/β-heteroatom elimination sequence of an in situ formed zirconium hydride catalyst. The positional isomerization of the catalyst further enables the cleavage of homoallylic ethers and the removal of terminal allyl and propargyl groups.
Matt, Christof,K?lblin, Frederic,Streuff, Jan
supporting information
p. 6983 - 6988
(2019/09/09)

Competing dehalogenation versus borylation of aryl iodides and bromides under transition-metal-free basic conditions
In this work, selectivity-controllable base-promoted transition-metal-free borylation and dehalogenation of aryl halides are described. Under the conditions of borylation, the dehalogenation which emerges as a competitive side reaction has been well-controlled by carefully controlling the borylation conditions. On the other hand, the dehalogenation using benzaldehyde as a hydrogen source has also been accomplished. The applications of direct radical borylation and dehalogenation of aryl halides demonstrate their synthetic practicability in pharmaceutical-oriented organic synthesis. Based on the experimental evidences, the tBuOK/1,10-Phen-triggered radical nature of both competitive reactions has been revealed.
Niu, Yi-Jie,Sui, Guo-Hui,Zheng, Hong-Xing,Shan, Xiang-Huan,Tie, Lin,Fu, Jia-Le,Qu, Jian-Ping,Kang, Yan-Biao
p. 10805 - 10813
(2019/09/30)

Decarboxylative C(sp3)?O Cross-Coupling
Alkyl aryl ethers are an important class of compounds in medicinal and agricultural chemistry. Catalytic C(sp3)?O cross-coupling of alkyl electrophiles with phenols is an unexplored disconnection strategy to the synthesis of alkyl aryl ethers, with the potential to overcome some of the major limitations of existing methods such as C(sp2)?O cross-coupling and SN2 reactions. Reported here is a tandem photoredox and copper catalysis to achieve decarboxylative C(sp3)?O coupling of alkyl N-hydroxyphthalimide (NHPI) esters with phenols under mild reaction conditions. This method was used to synthesize a diverse set of alkyl aryl ethers using readily available alkyl carboxylic acids, including many natural products and drug molecules. Complementarity in scope and functional-group tolerance to existing methods was demonstrated.
Mao, Runze,Balon, Jonathan,Hu, Xile
supporting information
p. 13624 - 13628
(2018/09/25)

Copper(I)-USY as a Ligand-Free and Recyclable Catalyst for Ullmann-Type O-, N-, S-, and C-Arylation Reactions: Scope and Application to Total Synthesis
The copper(I)-doped zeolite CuI-USY proved to be a versatile, efficient, and recyclable catalyst for various Ullmann-type coupling reactions. Easy to prepare and cheap, this catalytic material enables the arylation and heteroarylation of diverse O-, N-, S-, and C-nucleophiles under ligand-free conditions while exhibiting large functional group compatibility. The facility of this catalyst to promote C-O bond formation was further demonstrated with the total synthesis of 3-methylobovatol, a naturally occurring diaryl ether of biological relevance. From a mechanistic viewpoint, two competitive pathways depending on the nature of the nucleophile and consistent with the obtained results have been proposed.
Garnier, Tony,Danel, Mathieu,Magné, Valentin,Pujol, Anthony,Bénéteau, Valérie,Pale, Patrick,Chassaing, Stefan
p. 6408 - 6422
(2018/05/31)

Benzene C-H Etherification via Photocatalytic Hydrogen-Evolution Cross-Coupling Reaction
Aryl ethers can be constructed from the direct coupling between the benzene C-H bond and the alcohol O-H bond with the evolution of hydrogen via the synergistic merger of photocatalysis and cobalt catalysis. Utilizing the dual catalyst system consisting of 3-cyano-1-methylquinolinum photocatalyst and cobaloxime, intermolecular etherification of arenes with various alcohols and intramolecular alkoxylation of 3-phenylpropanols with formation of chromanes are accomplished. These reactions proceed at remarkably mild conditions, and the sole byproduct is equivalent hydrogen gas.
Zheng, Yi-Wen,Ye, Pan,Chen, Bin,Meng, Qing-Yuan,Feng, Ke,Wang, Wenguang,Wu, Li-Zhu,Tung, Chen-Ho
supporting information
p. 2206 - 2209
(2017/05/12)

Conversion of Cyclohexanones to Alkyl Aryl Ethers by Using a Pd/C–Ethylene System
The conversion of cyclohexanone and substituted cyclohexanones into alkyl aryl ethers by using a Pd/C–ethylene system is discussed, with ethylene functioning as a hydrogen acceptor. The ether products are easily transformed into the corresponding phenols by treatment with BBr3. The direct conversion of cyclohexenone into phenol in the presence of a catalytic amount of Pd/C under an ethylene atmosphere is also described.
El-Deeb, Ibrahim Yussif,Tian, Miaomiao,Funakoshi, Tatsuya,Matsubara, Ryosuke,Hayashi, Masahiko
p. 409 - 413
(2017/01/24)

Characterization of a selective inverse agonist for estrogen related receptor α as a potential agent for breast cancer
The estrogen-related receptor α (ERRα) is an orphan nuclear receptor that plays a primary role in the regulation of cellular energy homeostasis and osteogenesis. It is reported that ERRα is widely expressed in a range of tissues and accumulating evidence has supported that the high expression of ERRα correlates with poor prognosis of various human malignancies, including breast, endometrium, colon, prostate and ovary cancers. Herein is described the discovery of a novel selective inverse agonist (HSP1604) of ERRα, but not of ERRβ and ERRγ, as determined using transient transfection luciferase reporter assay and a time-resolved fluorescence resonance energy transfer (TR-FRET) co-activator assay. HSP1604 potently inhibits ERRα transcriptional activity with IC50=1.47±0.17?μM in cell-based luciferase reporter assay and also decreases the protein level of ERRα and the mRNA levels of its downstream target genes such as pyruvate dehydrogenase kinase 4 (PDK4), pS2 and osteopontin. HSP1604 has also suppressed the proliferation of different human cancer cell lines and the migration of breast cancer cells with high expression of ERRα. Representative in vivo results show that HSP1604 suppresses the growth of human breast cancer xenograft in nude mice as doses at 30?mg/kg or 100?mg/kg administered every other day during 28-day period. HSP1604 thus has the potential both as a new agent to inhibit the growth of tumors and as a chemical probe of ERRα biology.
Zhang, Liudi,Liu, Peihong,Chen, Haifei,Li, Qunyi,Chen, Lu,Qi, Huijie,Shi, Xiaojin,Du, Yongli
p. 439 - 448
(2016/08/17)

Efficient synthesis of diphenyl carbonate from dibutyl carbonate and phenol using square-shaped Zn-Ti-O nanoplates as solid acid catalysts
Square-shaped Zn/Ti oxides were prepared by a co-precipitation method and used for the synthesis of diphenyl carbonate (DPC) via transesterification of dibutyl carbonate (DBC) with phenol. The results showed that a 51% yield of butyl phenyl carbonate (BPC) and 13% yield of DPC could be achieved at 205 °C in the presence of 3ZnTi-400 (Zn : Ti molar ratio 3 : 1). Moreover, it is found that 3ZnTi-400 was also an active catalyst for the disproportionation of BPC to DPC, and 80% conversion of BPC was obtained at 190 °C. The prepared catalysts could be reused for three runs of the transesterification without noticeable deactivation. The catalysts were characterized by XRD, SEM, XPS, and TPD with the aim of establishing the relationship between catalytic performance and structure.
Wang, Peixue,Liu, Shimin,Zhou, Feng,Yang, Benqun,Alshammari, Ahmad S.,Deng, Youquan
p. 84621 - 84626
(2015/10/28)

Iron-catalyzed olefin hydrogenation at 1 bar H2 with a FeCl3-LiAlH4 catalyst
The scope and mechanism of a practical protocol for the iron-catalyzed hydrogenation of alkenes and alkynes at 1 bar H2 pressure were studied. The catalyst is formed from cheap chemicals (5 mol% FeCl3-LiAlH4, THF). A homogeneous mechanism operates at early stages of the reaction while active nanoparticles form upon ageing of the catalyst solution. This journal is
Gieshoff, Tim N.,Villa, Matteo,Welther, Alice,Plois, Markus,Chakraborty, Uttam,Wolf, Robert,Jacobi Von Wangelin, Axel
p. 1408 - 1413
(2015/03/18)

Novel, potent, selective and cellular active ABC type PTP1B inhibitors containing (methanesulfonyl-phenyl-amino)-acetic acid methyl ester phosphotyrosine mimetic
Protein tyrosine phosphatase 1B (PTP1B) which plays an important role in the negative regulation of insulin and leptin pathway has emerged as a novel promising therapeutic target for the treatment of type 2 diabetes mellitus and obesity. Upon careful study, a series of novel scaffold and simple synthesis method inhibitors were discovered based on the analysis of X-ray crystal structures of PTP1B/inhibitor complexes and docking simulations. Among them, compound P7 exhibited high inhibitory activity (IC50 = 222 nM) with moderate selectivity (8-fold) over T-cell PTPase (TCPTP) through interacting with the A, B and C binding sites of PTP1B enzyme. Further studies on cellular activities revealed that compound P7 could enhance insulin-mediated IRβ phosphorylation and insulin-stimulated glucose uptake.
Liu, Peihong,Du, Yongli,Song, Lianhua,Shen, Jingkang,Li, Qunyi
p. 7079 - 7088
(2015/11/11)

Nanosized ferric hydroxide catalyzed c-o cross-coupling of phenol and halides to generate phenoxy ether
The iron-based catalyst can effectively catalyze the phenolic hydroxyl C-O bond formation reaction to give the corresponding phenoxy ethers. The reaction of phenol and methyl chloroacetate, for example, gives phenoxy acetic acid methyl ester in 98 % yield under the optimal reaction conditions. Among the iron-based catalysts, nanosized ferric hydroxide prepared through sol-gel method gives the best catalytic activity.
Sun, Hongbin,Sun, Yuanhua,Tian, Xiaohua,Zhao, Yunxia,Qi, Xuan
p. 6189 - 6191
(2013/07/26)

Synthesis of aryl ethers from benzoates through carboxylate-directed C-H-activating alkoxylation with concomitant protodecarboxylation
One in, one out: In the presence of a copper/silver bimetallic catalyst system, aromatic carboxylate salts undergo ortho C-H alkoxylation with concomitant loss of the carboxylate directing group in a protodecarboxylation step (see scheme, FG=functional group). This process provides a convenient synthetic access to the important class of aromatic ethers from widely available carboxylic acids. Copyright
Bhadra, Sukalyan,Dzik, Wojciech I.,Goo?en, Lukas J.
p. 2959 - 2962
(2013/04/10)

Synthesis of aryl ethers from aromatic carboxylic acids
A silver/copper bimetallic catalyst system promotes the decarboxylative Chan-Evans-Lam alkoxylation of ortho-substituted aromatic carboxylate salts with tetraalkyl orthosilicates or triaryl borates. Non-ortho-substituted carboxylates are alkoxylated via an ortho-C-H-alkoxylation with concomitant cleavage of the carboxylate directing group via protodecarboxylation. This way, meta-substituted carboxylates are converted into para-substituted alkoxyarenes and vice versa. The combined processes provide a convenient synthetic entry to the important class of aromatic ethers from widely available carboxylic acids.
Bhadra, Sukalyan,Dzik, Wojciech I.,Goossen, Lukas J.
supporting information
p. 2387 - 2390
(2013/09/23)

Azodicarbonyl dimorpholide (ADDM): An effective, versatile, and water-soluble Mitsunobu reagent
One of the caveats of the Mitsunobu reaction is the often difficult and laborious purification of the reaction mixture. Herein, we show that azodicarbonyl dimorpholide (ADDM) is an effective and versatile Mitsunobu reagent, which, along with its reduced form ADDM-H2, may be removed from the reaction mixture by a simple aqueous extraction. Furthermore, we demonstrate that the isolated ADDM-H2 may be re-oxidized with silver(I) oxide to regenerate ADDM. Finally, a chromatography-free Mitsunobu reaction is presented.
Lanning, Maryanna E.,Fletcher, Steven
p. 4624 - 4628
(2013/08/23)

Cross-coupling of alkyl halides with aryl or alkyl Grignards catalyzed by dinuclear Ni(ii) complexes containing functionalized tripodal amine-pyrazolyl ligands
Structurally distinctive dinuclear Ni(ii) complexes with furan or thiophene tethered amine-pyrazolyl tripodal hybrid ligands have been synthesized and crystallographically characterized. All complexes are catalytically active towards cross-coupling of aryl/alkyl Grignard reagents with β-H containing alkyl halides at room temperature in the presence of N,N,N',N'- tetramethylethylenediamine (TMEDA). The catalytic efficacy of the complexes is dependent on the tether substituent at the central amine. Two species, Ni(ii) TMEDA and Mg(ii) TMEDA complexes, have been isolated from the catalytic reaction mixtures under different conditions. Some ligand-stabilized Ni(ii) and Mg(ii) bimetallic species have also been identified in the ESI-MS spectra.
Xue, Fei,Zhao, Jin,Hor, T. S. Andy
p. 5150 - 5158
(2013/04/10)

Alkoxylation reactions of aryl halides catalyzed by magnetic copper ferrite
Copper ferrite (CuFe2O4), which is easy-made, air-stable, low cost, easy separable, and regenerable, was applied as catalyst in an efficient method for C-O coupling reactions between various kinds of unactivated alkyl alcohols and aryl halides. This method only adopts 2.5% mol CuFe2O4 catalyst and selectively proceeds to C-O bond formation even sensitive substituents exist in the system.
Yang, Shuliang,Xie, Wenbing,Zhou, Hua,Wu, Cunqi,Yang, Yanqin,Niu, Jiajia,Yang, Wei,Xu, Jingwei
supporting information
p. 3415 - 3418
(2013/04/23)

Effects of charge separation, effective concentration, and aggregate formation on the phase transfer catalyzed alkylation of phenol
The factors that influence the rate of alkylation of phenol under phase transfer catalysis (PTC) have been investigated in detail. Six linear, symmetrical tetraalkylammonium cations, Me4N+, Et 4N+, (n-Pr)4N+, (n-Bu) 4N+, (n-Hex)4N+, and (n-Oct) 4N+, were examined to compare the effects of cationic radius and lipophilicity on the rate of alkylation. Tetraalkylammonium phenoxide·phenol salts were prepared, and their intrinsic reactivity was determined from initial alkylation rates with n-butyl bromide in homogeneous solution. The catalytic activity of the same tetraalkylammonium phenoxides was determined under PTC conditions (under an extraction mechanism) employing quaternary ammonium bromide catalysts. In homogeneous solution the range in reactivity was small (6.8-fold) for Me4N+ to (n-Oct) 4N+. In contrast, under PTC conditions a larger range in reactivity was observed (663-fold). The effective concentration of the tetraalkylammonium phenoxides in the organic phase was identified as the primary factor influencing catalyst activity. Additionally, titration of active phenoxide in the organic phase confirmed the presence of both phenol and potassium phenoxide aggregates with (n-Bu)4N+, (n-Hex)4N+, and (n-Oct)4N+, each with a unique aggregate stoichiometry. The aggregate stoichiometry did not affect the PTC initial alkylation rates.
Denmark, Scott E.,Weintraub, Robert C.,Gould, Nathan D.
p. 13415 - 13429
(2012/09/25)

Synthesis and characterization of novel starburst phase transfer catalyst
A new phase transfer catalyst, 3,5-bis[(2-methyl-naphthylene-1 -yl)-phenylamino-phenyl]-butyl-(2methoxy-naphthalene-1 -yl)-phenylammonium bromide (BPBPB) has been synthesized, characterized using spectral analysis and its catalytic activity ascertained. Efficiency of BPBPB is studied using etherification of phenol and compared with tetra butyl ammonium bromide (TBAB). O-Alkylation of naphthol, iV-alkylation of indole and halogen substitution reactions are carried out using BPBPB and its efficiency is compared with reported PTCs. BPBPB gives high yield of product, the time for completion of the reaction is short and is required in a very low concentration. Almost 95% of this catalyst is regenerated and reused.
Mathew, Siji,Divia,Nair, T.D. Radhakrishnan,Haridas, Karickal R.
scheme or table
p. 1389 - 1393
(2011/01/13)

Three component reaction of arynes with cyclic ethers and active methines: Synthesis of ω-trichloroalkyl phenyl ethers
Synthesis of ω-chlorinated alkyl phenyl ethers by tandem reaction of arynes with cyclic ethers and active methines was achieved. Reaction of benzenediazonium 2-carboxylate with tetrahydropyran or tetrahydrofuran in refluxing chloroform afforded 6,6,6-trichlorohexyl phenyl ether or 5,5,5-trichloropentyl phenyl ether in 40% and 61% yields, respectively. When dichloroacetonitrile was used as a reactant, 5,5-dichloro-5-cyanopentyl phenyl ether was obtained in 61% yield. While benzenediazonium carboxylate did not react with epoxides, reaction of benzyne derived from 2-(trimethylsilyl)phenyl triflate with epoxides afforded 3,3,3-trichloropropyl phenyl ethers in good yields as isomeric mixtures. The reaction of oxetanes with benzyne was also reported.
Okuma, Kentaro,Fukuzaki, Yuta,Nojima, Akiko,Sou, Ayumi,Hino, Haruna,Matsunaga, Nahoko,Nagahora, Noriyoshi,Shioji, Kosei,Yokomori, Yoshinobu
experimental part
p. 1238 - 1247
(2010/12/20)

Radical alkylations of alkyl halides and unactivated C-H bonds using vinyl triflates
Radical alkylations of activated alkyl iodides and bromides were achieved using vinyl triflates in the presence of hexadimethyltin, whereas those of unactivated C-H bonds using vinyl triflates proceeded cleanly under tin-free conditions. Georg Thieme Verl
Lee, Jin Young,Lim, Kyoung-Chan,Meng, Xiangjian,Kim, Sunggak
experimental part
p. 1647 - 1650
(2010/09/04)

NOVEL SEMI-SYNTHETIC GLYCOPEPTIDES AS ANTIBACTERIAL AGENTS
Semi-synthetic glycopeptides having antibacterial activity are described, in particular, the semi-synthetic glycopeptides described herein are made by chemical modification of the a glycopeptide (Compound A, Compound B, Compound H or Compound C) or the monosaccharide made by hydrolyzing the disaccharide moiety of the amino acid-4 of the parent glycopeptide in acidic medium to give the amino acid-4 monosaccharide; conversion of the monosaccharide to the amino-sugar derivative; acylation of the amino substituent on the amino acid-4 amino-substituted sugar moiety on these scaffolds with certain acyl groups; conversion of the amide group in amino acid-3 on these scaffolds to various acylamide, acylsulfonamide, acylsulfonylurea derivatives; aminomethylation with substituent containing sulfonamide or acylsulfonamide group on amino acid-7 through Mannich reaction; and conversion of the acid moiety on the macrocyclic ring of these scaffolds to certain substituted amides. Also provided are methods for the synthesis of the compounds, pharmaceutical compositions containing the compounds, and methods of use of the compounds for the treatment and/or prophylaxis of diseases, especially bacterial infections.
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(2015/03/06)

Hydrogenation of olefins using Hantzsch ester catalyzed by palladium on carbon
Hantzsch 1,4-dihydropyridine (HEH), a well-known model compound of coenzyme NAD(P)H was found as an efficient reducing agent in hydrogenation of unactivated olefins catalyzed by Pd/C. α,β-Unsaturated ketones also underwent hydrogenation, affording the corresponding saturated ketones selectively.
Liu, Qiang,Li, Jing,Shen, Xiao-Xia,Xing, Rui-Guang,Yang, Jie,Liu, Zhengang,Zhou, Bo
scheme or table
p. 1026 - 1028
(2009/05/11)

Copper(I)-catalyzed aryl bromides to form intermolecular and intramolecular carbon-oxygen bonds
(Chemical Equation Presented) A highly efficient Cu-catalyzed C-O bond-forming reaction of alcohol and aryl bromides has been developed. This transformation was realized through the use of copper(I) iodide as a catalyst, 8-hydroxyquinoline as a ligand, and K3PO4 as a base. A variety of functionalized substrates were found to react under these reaction conditions to provide products in good to excellent yields.
Niu, Jiajia,Guo, Pengran,Kang, Juntao,Li, Zhigang,Xu, Jingwei,Hu, Shaojing
scheme or table
p. 5075 - 5078
(2009/10/17)

A process for the rapid removal of dialkylamino-substituents from aromatic rings. Application to the expedient synthesis of (R)-tolterodine
A range of N,N-dialkylanilines have been successfully converted to the parent substituted benzenes by a novel two-step pathway. The products are obtained in good yields and optical purity of adjacent stereocenters is maintained. This technology has been applied toward the synthesis of (R)-tolterodine.
Paras, Nick A.,Simmons, Bryon,MacMillan, David W.C.
experimental part
p. 3232 - 3238
(2009/08/15)

Radical cyanation of alkyl iodides with diethylphosphoryl cyanide
The β-elimination of an organophosphoryl group from an iminyl radical is observed for the first time. On the basis of this finding, radical cyanation of alkyl iodides is achieved by using diethylphosphoryl cyanide. Georg Thieme Verlag Stuttgart.
Chang, Ho Cho,Jin, Young Lee,Kim, Sunggak
experimental part
p. 81 - 84
(2009/05/30)

An efficient Ullmann-type C-O bond formation catalyzed by an air-stable copper(I)-bipyridyl complex
(Chemical Equation Presented) An efficient O-arylation of phenols and aliphatic alcohols with aryl halides was developed that uses an air-stable copper(I) complex as the catalyst. This arylation reaction can be performed in good yield in the absence of Cs2CO3. A variety of functional groups are compatible with these reaction conditions with low catalyst loading levels.
Niu, Jiajia,Zhou, Hua,Li, Zhigang,Xu, Jingwei,Hu, Shaojing
p. 7814 - 7817
(2008/12/22)

A comparative study on the binding behaviors of β-cyclodextrin and its two derivatives to four fanlike organic guests
(Figure Presented) Four fanlike organic compounds, 1-ethoxybenzene (EOB), 1-butoxybenzene (BOB), 1-dodecyloxybenzene (DOB), and 1-(dodecyloxy)-2- methoxybenzene (DOMB), were chosen as guests, and β-cyclodextrin (β-CD) and its two derivatives, mono(2-O-2-methyl)-β-CD and mono(2-O-2-hydroxy-propyl)-β-CD, were chosen as hosts. Energy changes involved in host-guest inclusion processes were clearly obtained by applying semiempirical PM3 calculations. According to this, probable structures of the host-guest inclusion complexes were proposed. The inclusion systems in aqueous solution were investigated by UV-vis spectroscopy and nuclear magnetic resonance (1H NMR) titration, and the formation constants (K) of the inclusion complexes were determined using the Benesi-Hildebrand equation. Moreover, two solid inclusion complexes of β-CD with EOB and DOB were prepared and characterized by Fourier transform infrared spectra, X-ray powder diffraction, 1H NMR, electrospray ionization mass spectrometry, and thermogravimetric analyses. Results showed that the host-guest stoichiometrics in the inclusion complexes were all 1:1 both in solid state and in aqueous solution. As for the same host, the values of K increased in the order EOB BOB DOB, in strong association with the fan handle in the fanlike molecules; that is to say, the K values increased with increasing carbon chain length of substituent on benzene ring. In addition, the K values of DOMB complexes were larger than those of DOB complexes for the same CD, indicating that the introduction of an extra o-methoxyl group on DOB further stabilized the CD inclusion complexes. The decomposition activation energies of EOB-β-CD and DOB-β-CD were very similar but significantly larger than that of free β-CD.
Le, Xin Song,Hai, Ming Wang,Xue, Qing Guo,Bai, Lei
experimental part
p. 8305 - 8316
(2009/04/11)

Synthesis and reactivity profiles of phosphinated poly(alkyl aryl ether) dendrimers
Poly(alkyl aryl ether) dendrimers were utilized to synthesize a series of new triphenylphosphine functionalized dendrimers. Zero, first, second and third generation dendrimers, carrying 3, 6, 12 and 24 triphenylphosphine units, were prepared and characterized. The new triphenylphosphine containing dendrimers were assessed for their reactivity profiles and in this instance, the dendrimers were used as reagents to mediate Mitsunobu etherification reaction between phenol and various primary, secondary and benzylic alcohols. In addition, dendritic poly-phenols were also tested in an O-benzylation reaction. A monomeric methoxy group attached triphenylphosphine acted as a control for comparison of reactivity profiles of dendrimers. It was observed that the etherification reaction was mediated efficiently by the dendritic reagent, and in addition, the dendritic phosphine oxide reagents could be recovered quantitatively by precipitation methods. The recovered dendritic phosphine oxides were reduced subsequently to the corresponding phosphines and used as reagents for the Mitsunobu reaction, repetitively.
Nithyanandhan, Jayaraj,Jayaraman, Narayanaswamy
p. 11184 - 11191
(2007/10/03)

Organosoluble copper clusters as precatalysts for carbon - Heteroelement bond-forming reactions: Microwave and conventional heating
(Chemical Equation Presented). The coupling of aryl iodides with alcohols under mild conditions has been explored using self-assembled octanuclear copper clusters as catalysts. Reactions involving tetrahydrofurfuryl alcohol were typically complete in 4-8
Manbeck, Gerald F.,Lipman, Adam J.,Stockland Jr., Robert A.,Freidl, Adrienne L.,Hasler, Amy F.,Stone, Joshua J.,Guzei, Ilia A.
p. 244 - 250
(2007/10/03)

Copper-catalyzed etherification of aryl iodides using KF/Al 2O3: An improved protocol
A simple and efficient method for the coupling of aryl iodides with aliphatic alcohols and phenols that does not require the use of alkoxide bases is described. This C-O bond forming procedure shows that the combination of air stable CuI and 1,10-phenanthroline in the presence of KF/Al2O 3 comprises an extremely efficient and general catalyst system for the etherification of aryl iodides. Different functionalized aryl iodides were coupled with alcohols and phenols using this method.
Hosseinzadeh, Rahman,Tajbakhsh, Mahmood,Mohadjerani, Maryam,Alikarami, Mohammad
p. 1101 - 1104
(2007/10/03)

Use of tunable ligands allows for intermolecular Pd-catalyzed C-O bond formation
Bulky biaryl phosphine ligands facilitate Pd-catalyzed C-O coupling reactions of aryl halides with primary and secondary alcohols by promoting reductive elimination at the expense of β-hydride elimination. The key to their success is the ability to match the size of the ligand to that of the combination of substrates. The efficient coupling of a number of unactivated aryl chlorides and bromides with cyclic and acyclic secondary alcohols was achieved. This included the coupling of allylic alcohols for the first time in a Pd-catalyzed coupling process.
Vorogushin, Andrei V.,Huang, Xiaohua,Buchwald, Stephen L.
p. 8146 - 8149
(2007/10/03)

An efficient lutidine-assisted etherification of phenols with alkyl chloride in water
An efficient etherification of phenol derivatives with alkyl chloride in water was achieved. The reactivity of the ether bond forming reaction was activated by addition of 2,6-lutidine.
Aki, Shinji,Nishi, Takao,Minamikawa, Jun-Ichi
p. 940 - 941
(2007/10/03)

Application of alkoxy-λ6-sulfanenitriles as strong alkylating reagents
Alkoxy-λ6-sulfanenitriles were found to be versatile alkylating reagents toward various nucleophiles bearing at least one proton such as methanol, phenol, thiophenols, carboxylic acids, ptoluenesulfonic acid, hydrochloric acid, and primary and secondary amines. Reactivity of the alkoxy group of the λ6-sulfanenitriles showed an opposite trend to the usual SN2 character, i.e. Me (la), Pr (1b), and Bu (1d) ? i-Pr (1c). In the presence of p-TsOH, alkyl tosylates were predominantly formed instead of the alkylation products of nucleophiles. In addition, even a sterically hindered substrate, neopentyloxy-λ6-sulfanenitrile, was found to undergo an SN2 reaction toward thiophenol without any rearrangement product to give neopentyl phenyl sulfide in good yield.
Hao, Wei,Fujii, Takayoshi,Dong, Tiaoling,Wakai, Youko,Yoshimura, Toshiaki
p. 193 - 198
(2007/10/03)

Preparation of 1-Alkoxy-1,3-cyclohexadienes via Iron Complexation/Decomplexation
A synthetic method for the preparation of 1-alkoxy-1,3-cyclohexadienes is presented. Iron complexation/decomplexation is used to produce and purify the desired compound without contamination of isomeric by products.
Rennels, Roger A.,McClusky, John V.
p. 651 - 656
(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)

Design of polyaromatic hydrocarbon-supported tin reagents: A new family of tin reagents easily removable from reaction mixtures
We report in this paper the preparation and use of stannanes 11, 12a, and 12b, compounds whose 3-pyrenylpropyl side chain affinity for activated carbon simplifies tin removal and product isolation. Our pyrene-supported reagents can be used for radical reductions and cyclizations (11), radical and cationic allylations (12a), and Stille couplings (12b) in much the same way as tributyltin derivatives.
Stien, Didier,Gastaldi, Stephane
p. 4464 - 4470
(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
p. 22 - 23
(2007/10/03)

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)

PAH-supported tin hydride: A new tin reagent easily removable from reaction mixtures
We demonstrate here that a new pyrene-supported tin hydride can be used in radical chemistry. Final products were easily purified by adsorption of the PAH-supported tin side product with activated carbon.
Gastaldi, Stéphane,Stien, Didier
p. 4309 - 4311
(2007/10/03)