- Potassium fluoride supported on natural nanoporous zeolite: A new solid base for the synthesis of diaryl ethers
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An efficient and inexpensive synthesis of diaryl ethers has been developed. The process involves the nucleophilic aromatic substitution of electron-deficient aryl halides and phenols and is mediated by potassium fluoride/Clinoptilolite (KF/CP) in dimethyl sulfoxide (DMSO). The approach affords good to excellent yields of the arylated products without the need for additional cation capture. The solid base is also efficient in the Ullmann ether synthesis. A new, inexpensive solid base for the synthesis of diaryl ethers has been developed. Clinoptilolite, a natural zeolite with a high tendency for cation capture, combined with potassium fluoride, provides an efficientsolid base for the deprotonation of phenols in nucleophilic reactions. The same solid base acts as a reliable base for the copper-catalyzed synthesis of diaryl ethers. Copyright
- Khalilzadeh, Mohammad A.,Hosseini, Abolfazl,Pilevar, Afsaneh
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experimental part
p. 1587 - 1592
(2011/04/22)
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- Design and synthesis of aryloxyethyl thiocyanate derivatives as potent inhibitors of Trypanosoma cruzi proliferation
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As a part of our project directed at the search of new chemotherapeutic agents against American trypanosomiasis (Chagas' disease), several drugs possessing the 4-phenoxyphenoxy skeleton and other closely related structures employing the thiocyanate moiety as polar end group were designed, synthesized, and evaluated as antiproliferative agents against Trypanosoma cruzi, the parasite responsible for this disease. These thiocyanate analogues were envisioned bearing in mind the potent activity shown by 4- phenoxyphenoxyethyl thiocyanate (compound 8) taken as lead drug. This compound had previously proved to be an extremely active growth inhibitor against T. cruzi with IC50 values ranging from the very low micromolar level in epimastigotes to the low nanomolar level in the intracellular form of the parasite. Of the designed compounds, the ethyl thiocyanate drugs connected to nonpolar skeletons, namely, arylthio, 2,4-dichlorophenoxy, ortho-substituted aryloxy, and 2-methyl-4-phenoxyphenoxy (compounds 15, 34, 47, 52, 72, respectively), were shown to be very potent antireplicative agents against T. cruzi. On the other hand, conformationally restricted analogues as well as branched derivatives at the aliphatic side chain were shown to be moderately active against T. cruzi growth. The biological activity of drugs bearing the thiocyanate group correlated quite well with the activity exhibited by their normal precursors, the tetrahydropyranyl ether derivatives, when bonded to the same nonpolar skeleton. Compounds having the tetrahydropyranyl moiety as polar end were proportionally much less active than sulfur-containing derivatives in all cases. Drugs 47 and 72 also resulted to be very active against the amastigote form of the parasite growing in myoblasts; however, they were slightly less active than the lead drug 8. On the other hand, compounds 34 and 52 were almost devoid of activity against myoblasts. Surprisingly, the dithio derivative 15 was toxic for myoblasts.
- Szajnman, Sergio H.,Yan, Wen,Bailey, Brian N.,Docampo, Roberto,Elhalem, Eleonora,Rodriguez, Juan B.
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p. 1826 - 1840
(2007/10/03)
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- A NOVEL, SIMPLE METHOD FOR THE PREPARATION OF HINDERED DIPHENYL ETHERS
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The displacement of the nitro group from substituted nitrobenzenes is used for the synthesis of diphenyl ethers. 1,4-Dinitrobenzene has been converted into a variety of hindered diphenyl ethers using 2,6-disubstituted phenoxides and studies show that the mechanism of formation of the ether (5a) is radical in nature.
- Sammes, Peter G.,Thetford, Dean,Voyle, Martyn
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p. 3229 - 3232
(2007/10/02)
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- Displacement of an Aromatic Nitro Group using Phenoxides
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1,4-dinitrobenzene undergoes nucleophilic substitution with sodium phenoxide and several hindered 2,6-disubstituted phenoxides to afford diphenyl ethers.
- Sammes, P. G.,Thetford, D.,Voyle, M.
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p. 1373 - 1374
(2007/10/02)
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