1126-79-0Relevant academic research and scientific papers
OPTIMIZATION OF POLYMER-SUPPORTED OLIGOETHERS AS SOLID-LIQUID PHASE TRANSFER CATALYSTS
Heffernan, J.G.,Sherrington, D.C.
, p. 1661 - 1664 (1983)
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.
Non-supported and Resin-supported Oligo(oxyethylenes) as Solid-Liquid Phase-transfer Catalysts. Effect of Chain Length and Head-group
Heffernan, James G.,MacKenzie, William M.,Sherrington, David C.
, p. 514 - 517 (1981)
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.
Stealth star polymers: A new high-loading scaffold for liquid-phase organic synthesis
Reed, Neal N.,Janda, Kim D.
, p. 1311 - 1313 (2000)
(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.
Magnetically separable phase-transfer catalysts
Kawamura, Masato,Sato, Kazuhiko
, p. 4718 - 4719 (2006)
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.
Use of diethoxymethane as a solvent for phase transfer-catalyzed O -alkylation of phenols
Coleman, M. Todd,Leblanc, Gabriel
, p. 732 - 736 (2010)
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.
Approximate rate constants for intermolecular additions of alkyl radicals to phenylsulfonyl oxime ethers
Kim, Sunggak,Lee, Ill Young
, p. 1587 - 1590 (1998)
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.
N-ARYL SULFONAMIDE DERIVATIVES AS VACCINE ADJUVANT
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Page/Page column 101-102, (2021/02/26)
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.
Radical Anion Promoted Chemoselective Cleavage of Csp2-S Bond Enables Formal Cross-Coupling of Aryl Methyl Sulfones with Alcohols
Bai, Jixiang,Wang, Tianxin,Dai, Botao,Liu, Qingchao,Yu, Peiyuan,Jia, Tiezheng
supporting information, p. 5761 - 5765 (2021/08/16)
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.
Methylation with Dimethyl Carbonate/Dimethyl Sulfide Mixtures: An Integrated Process without Addition of Acid/Base and Formation of Residual Salts
Chan, Bun,Lui, Matthew Y.,Lui, Yuen Wai
, (2022/01/08)
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.
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
Mohammadinezhad, Arezou,Akhlaghinia, Batool
, p. 332 - 352 (2020/01/11)
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.].
