Synthesis of new alkyl-type glycerolipids from methylthiomethyl ethers

The synthesis of alkyl-type glycerolipids with aliphatic and heterocyclic cationic “heads” separated by an acetal spacer from the glycerol core is described. The synthesis of sulfur-containing glycerolipids with an ether bond from rac-1-O-(2-bromoethoxy)methyl-2-O-ethyl-3-O-octadecylglycerol and functionalized thiols is considered.     

A mild method for the conversion of alcohols to methylthiomethyl ethers

Alcohols can be easily transformed to their corresponding methylthiomethyl ethers under mild conditions by treatment with methyl sulfide and benzoyl peroxide in acetonitrile.     

O-substituted alkyl aldehydes for rhodium-catalyzed intermolecular alkyne hydroacylation: the utility of methylthiomethyl ethers

Combining α-methylthiomethyl (MTM) ether substituted aldehydes and 1-alkynes in the presence of [Rh(dppe)]ClO(4) results in efficient intermolecular alkyne hydroacylation to deliver α-O-MTM-substituted enone products. The product MTM ethers can be converted to the free hydroxyl group either in situ, by the addition of water to the completed reaction, or in a separate operation, by the action of silver nitrate.     

Vinyl aryl ethers from copper-catalyzed coupling of vinyl halides and phenols

A general procedure for vinyl aryl ether bond formation by direct coupling of vinyl halides and phenols under mild Ullmann-type reaction conditions has been developed. Using copper chloride as the catalyst and cesium carbonate as the base, vinyl bromides or iodides were reacted with phenols in refluxing toluene to produce vinyl aryl ethers in good to excellent yields.     

Sulfated tungstate as hydroxyl group activator for preparation of benzyl,including p-methoxybenzyl ethers of alcohols and phenols

Sulfated tungstate was found to be an effective heterogeneous and reusable catalyst for hydroxy group activation–mediated preparation of benzylic ethers including p-methoxybenzylic ethers of a wide range of alcohols and phenols under mild reaction conditions.     

Rearrangements d'alkyl aryl ethers en phenols meta alkyles

In SbF₅-HF. ethers of para alkylated or 2.6-dialkylaled phenols give the corresponding meta alkylated phenols. For example, ethers 7, 9 and 21 give respectively the phenols 8,10, 22. Cross reactions, and use of deuterated substrates show that the mechanism implies alkylation of the O-protonated ether or phenol.     

Kinetics and mechanism of the reactions of diethylzinc with phenols in cyclic ethers

Reactions of diethylzinc and phenols (phenol, 2-ethylphenol, 2-chlorophenol, 3-ethylphenol, 3-chlorophenol, 4-ethylphenol and 4-chlorophenol) have been carried out in tetrahydrofuran and 1,4-dioxane as solvents. Monomeric ethylzinc phenoxide has been found to be a product of the diethylzinc and phenol (1:1) reaction in 1,4-dioxane solution. Kinetic studies on the ethylzinc phenoxides and phenols reaction in tetrahydrofuran solution established the rate constants and the S_Ei mechanism of the reaction.     

Protection des phenols par le groupement azidomethylene application a la synthese de phenols instables

Phenols are protected by the azidomethylene group in basic, nucleophilic, oxidative, weakly reductive and weakly acidic media. This group is obtained by the reaction of sodium azide with aryloxymethyl chlorides. Its utility lies in the ease with which it can be removed under very mild conditions which allows the synthesis of very unstable phenolic compounds.     

Direct synthesis of enaminone functionalized biaryl ethers by CuI-catalyzed O-arylation of enaminone functionalized phenols

The O-arylation of o-enaminone functionalized phenols, namely, (E)-3-(dimethylamino)-1-(2-hydroxyphenyl)prop-2-en-1-ones, has been achieved via a self-promoted process in the presence of CuI, which provided a class of new biaryl ethers bearing a reactive enaminone fragment. The reactions were performed under mild conditions and the functionalized biaryl ether products have been found as useful building blocks for the assembly of heterocyclic compounds.     

Application of ionic liquid halide nucleophilicity for the cleavage of ethers: a green protocol for the regeneration of phenols from ethers

We have used the high nucleophilicity of bromide ion in the form of the ionic liquid, 1-n-butyl-3-methylimidazolium bromide ([bmim][Br]), for the nucleophilic displacement of an alkyl group to regenerate a phenol from the corresponding aryl alkyl ether. Using 2-methoxynaphthalene (1) as a model compound, we found that the combination of ionic liquid [bmim][Br] and p-toluenesulfonic acid with warming effected demethylation in 14 h, affording the desired product 2-naphthol (2) in good yield (97%). Various other protic acids (MsOH, hydrochloric acid (35%), dilute sulfuric acid (50%)) could be used as a proton source in this demethylation reaction. Under the same conditions, cleavage of alkyl alkyl ether 2-(3-methoxypropyl)naphthalene yielded mixture of corresponding 2-(3-bromopropyl)naphthalene and 2-(3-hydroxypropyl)naphthalene. Dealkylation of various aryl alkyl ethers could also be achieved using significantly reduced (i.e., stoichiometric) amounts of concentrated hydrobromic acid (47%) in the ionic liquid. Both procedures afforded the desired products in moderate to good yield; however, cleavage of aryl alkyl cyclic ether, 2,3-dihydrobenzofuran, resulted in low yield of the desired product o-2-bromoethylphenol. The convenience of this method for ether cleavage and its effectiveness using only a moderate excess of hydrobromic acid make it attractive as a green chemical method.     

Synthesis of internal fluorinated alkenes via facile aryloxylation of substituted phenols with aryl trifluorovinyl ethers

Nucleophilic addition-elimination of ortho- or para-substituted phenols to aryl trifluorovinyl ethers (TFVEs) in N,N-dimethylformamide was studied. Using sodium hydride as a base afforded vinyl substitution products R-Ar-O-CF=CF-O-Ar-R', where R or R' = H, Br, OMe, tert-Bu, or Ph. The vinyl substitution products produced mixtures of (Z)/(E)-isomers and this isomer ratio was influenced by substitution with more sterically encumbered phenol nucleophiles. Reactions using caesium carbonate afforded addition products R-Ar-O-CHFCF(2)-O-Ar-R' whereas upon dehydrofluorination using sodium hydride produced vinyl substitution products. The preparation of vinyl substituted and addition products proceeded in overall good isolated yields and were elucidated using (1)H and (19)F NMR, GC-MS, and X-ray analysis. Vinyl substituted products were inert to UV light and chemical reactivity using common polymerization promoters. Thermal activation of the (Z)/(E)-fluoroolefin (-CF=CF-) was observed at an onset of 310 °C in nitrogen using differential scanning calorimetry (DSC) producing insoluble network material. The synthesis, characterization, and mechanism for stereoselectivity are discussed.     

A convenient procedure for the synthesis of allyl and benzyl ethers from alcohols and phenols

Allyl and benzyl ethers of alcohols can be prepared conveniently and in high yield with allyl and benzyl bromide in the presence of solid potassium hydroxide without use of any solvent. Phenols can be converted to allyl ethers but are inert to benzylation under above conditions.