Rhenium complex-catalyzed coupling reaction of enol acetates with alcohols

The reaction of enol acetates with alcohols in the presence of a catalytic amount of a rhenium complex, such as ReBr(CO)₅, produced the corresponding ketones and aldehydes in moderate to good yields. It was suggested that the preparation of an ether, an intermolecular dehydrated product, was the first step of the reaction.     

一个制备手性烯醇硅醚的新方法

本文合成了8个手性烯醇硅醚, 其中5个为新化合物, 其结构为IR, 1HNMR和MS所证实。     

Reactions of <Emphasis Type="Italic">p</Emphasis>-toluenesulfenyl chloride with enol acetates. The synthetic potential of the resulting adducts

Reactions of vinyl and propen-2-yl acetates with p-toluenesulfenyl chloride afforded the corresponding α-chloro-β-(p-tolyl)thioalkyl acetates in nearly quantitative yields.These adducts reacted with some C-nucleophiles in the presence of Lewis acids to give the corresponding alkylation products.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 730-734, March, 2005.     

Direct photolysis and electron transfer photooxygenation of enol acetates of 3-phenylpropiophenones

Summary Direct photolysis of enol acetates of 3-phenylpropiophenones1a–c gives rise to the parent propiophenones2a–c and the 1,3-acyl shift products3a–c. By contrast, 2,4,6-triphenylpyrylium tetrafluoroborate sensitized photolysis of substrates1a–c affords the -acetyloxypropiophenones7a–c as the most general products. These results have been rationalized according to the generation of radical pairs in the direct photolysis and radical cations in the photoinduced electron transfer processes.

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Direkte Photolyse und Flektron-Transfer-Photooxygenierung von Enolacetaten von 3-Phenylpropiophenonen

Zusammenfassung Die direkte Photolyse von Enolacetaten der 3-Phenylpropiophenone1a–c ergab die zugrundeliegenden Propiophenone2a–c und die 1,3-acyl-verschobenen Produkte3a–c. Im Gegensatz dazu ergab die 2,4,6-Triphenylpyrylium-tetrafluorborat-sensitivierte Photolyse der Substrate1a–c die -Acetyloxypropiophenone7a–c als generelle Produkte. Diese Ergebnisse sind mit der Erzeugung von Radikalpaaren bei der direkten Photolyse und der Bildung von Radikalkationen beim photoinduzierten Elektronen-Transfer-Prozess zu erklären.

     

1, 5-Rearrangement of enol acylates of aryl 1H.-1, 2, 4-triazol-1-ylmethyl ketones

The rearrangement of enol acylates of aryl 1H-1, 2, 4-triazol-1-ylmethyl ketones at 140–150°C in acetic anhydride is studied. The migration of the acyl group to the C(5) atom of the heterocycle is found to be intramolecular. The characteristics of the original and final products are presented. X-ray structural studies of the enol acetates of 2, 4-dichlorophenyl 1H-1, 2, 4-triazol-1-ylmethyl ketone and 2, 4-dichlorophenyl 5-acetyl-1H-1, 2, 4-triazol-1-ylmethyl ketone are carried out.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 560–564, March, 1993.     

Synthesis of vicinal perfluoroalkyl enol ethers

A convenient preparation of vicinal perfluoroalkyl enol ethers, by the action of alcohols on 1-bromo-1-perfluoroalkylethylenes in the presence of potassium hydroxide, is described. Some aspects of their reactivity are reported.     

Electrochemical study of the sequence of reductive dehalogenation of 2-bromo-5-dibromomethyl-4-dichloromethyl-4-methylcyclohexa-2,5-dien-1-one and its analogs

The electrochemical behavior of a series of halogen-containing cyclohexa-2,5-dien-1-ones at the glassy-carbon electrode in DMF was studied. The reductive dehalogenation of 2-bromo-5-dibromomethyl-4-dichloromethyl-4-methylcyclohexa-2,5-dien-1-one first results in the elimination of the carbonylallylic bromine atoms, then the carbonylic bromine atom is elimi-nated, and finally, the neopentylic chlorine atoms are eliminated. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1558–1564, September, 2006.     

New Polyfluorinated Cyanine Dyes for Selective NIR Staining of Mitochondria

In this communication, the synthesis of three unknown polyfluorinated cyanine dyes and their application as selective markers for mitochondria are presented. By incorporating fluorous side chains into cyanine dyes, their remarkable photophysical properties were enhanced. To investigate their biological application, several different cell lines were incubated with the synthesized cyanine dyes. It was discovered that the presented dyes can be utilized for selective near-infrared-light (NIR) staining of mitochondria, with very low cytotoxicity determined by MTT assay. This is the first time that polyfluorinated cyanine fluorophores are presented as selective markers for mitochondria. Due to the versatile applications of polyfluorinated fluorophores in bioimaging and materials science, it is expected that the presented fluorophores will be stimulating for the scientific community.     

Cobalt-catalyzed electrochemical vinylation of aryl halides using vinylic acetates

The electroreduction of aryl halides (bromides or chlorides) allows the coupling reaction with vinylic acetates, in the presence of 2,2-bipyridine and catalytic amounts of cobalt bromide, leading to styrene derivatives in good yields.     

PMA-SiO2 catalyzed synthesis of β-keto enol ethers

An efficient conversion of β-diketones into corresponding β-keto enol ethers with catalytic amount of PMA-SiO2 has been achieved.     

Carbonylation of Polyfluorinated 1-Arylalkan-1-ols and Diols in Superacids

We describe the carbonylation of a series of mono and dihydroxy derivatives of polyfluorinated alkylbenzenes and benzocycloalkenes with OH groups at benzylic positions using carbon monoxide in the presence of a superacid (TfOH, a TfOH–SbF₅ mixture, or a FSO₃H–SbF₅ mixture). It was shown that the superacid-catalyzed addition of CO to various primary and secondary polyfluorinated alcohols and diols gives the corresponding mono- and dicarboxylic acids or lactones. The efficiency of various superacids depending on alcohol structure was evaluated, and FSO₃H–SbF₅ yielded the best results in most transformations. The addition of CO to secondary 1-arylalkan-1-ols containing vicinal fluorine atoms was found to be accompanied by elimination of HF with the formation of α,β-unsaturated aryl-carboxylic acids. In contrast to primary and secondary alcohols, conversion of tertiary perfluoro-1,1-diarylalkan-1-ols into carbonylation products is not complete, and the resulting carboxylic acids are easily decarboxylated after water treatment of the reaction mixture.     

Platinum-catalyzed allylation of aminonaphthalenes with allylic acetates in water

The activation of C-O bonds in allylic acetates in water as a suspension medium has been accelerated by carrying out the reactions in the presence of platinum complexes associated with ligands. The platinum-catalyzed allylation of aminonaphthalenes using allylic acetates gave the corresponding N-allylic aminonaphthalenes in good yields.     

Zinc mediated propenylation of Baylis-Hillman acetates

Allyl bromide efficiently reacts with Baylis-Hillman acetates in the presence of zinc and copper iodide resulting in substituted 1,5-dienes.     

铁基双金属材料还原降解三溴甲烷的研究

本文制备了Cu/Fe和Pd/Fe两种铁基双金属材料,考察它们对溴仿(CHBr₃)的还原去除效果。结果表明,溴仿的还原去除效果都随双金属材料投加量的增加而增加;溶液中H⁺浓度越高,越有利于还原反应的进行;溶解氧的存在会对还原去除反应产生抑制作用。双金属材料与溴仿的还原去除反应包括直接还原和间接还原两种途径。Pd和Cu通过与零价铁组成原电池结构加快了零价铁在水中的腐蚀速度,从而增强了零价铁对溴仿的直接还原去除效果。Pd与Cu相比,具有更高的氢过电位,氢气更容易在Pd的表面生成,而氢气也可以作为还原剂,取代溴仿分子中的溴原子,完成还原脱卤。因此,Pd/Fe双金属材料对溴仿的还原去除效果要好于Cu/Fe双金属材料。     

Synthesis of substituted aryl enol ethers

A facile route toward substituted aryl diarylvinyl ethers 4 is developed from CuI-mediated cross-coupling reaction of substituted phenols 2 with diarylvinyl bromides 3 in the presence of various bidentate-based ligands in DMF. Skeleton 3 is prepared by Yan’s bromomethylenation of diarylketones 1 with CHBr₃–TiCl₄–Mg in the co-solvent of DME and CH₂Cl₂. The synthetic route obtains moderate yields from the one-step operation and the key structure of 4k is confirmed by X-ray crystallographic analysis. The CADD docking experiments of 4k have been included.     

Low temperature syntheses of thioketals from enol ethers and carbonyl compounds

A dithioacetalisation procedure at low temperature using TMSOTf as the promoter is described. This method proved highly efficient for unprecedented transprotection of ketone enol ethers and was successfully applied to polyfunctional sensitive substrates.     

Iodine-catalyzed synthesis of β-keto enol ethers

The use of iodine, as a catalyst for the synthesis of β-keto enol ethers at room temperature is reported.     

Determination of the substitution pattern in the polymer chain of cellulose acetates

Cellulose acetates have been investigated on different structural levels. Based on the determination of the acetate pattern of the monomers, a method has been developed to describe the distribution of the acetyl groups in the polymer chain. This approach comprises permethylation with methyl triflate, deacetylative deuteromethylation under alkaline conditions, random cleavage, remethylation with methyl-d₃, FAB-MS analysis and comparison of the experimental data with those calculated for a random acetate pattern. Results are discussed with respect to the conditions of the acetylation reactions. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3011–3016, 1999     

Titanocene-catalyzed metallation of propargylic acetates in homopropargyl alcohol synthesis

The titanium-catalyzed metallation and subsequent carbonyl addition of propargylic acetates enable the direct formation of homopropargylic alcohols in good yields. The corresponding products were obtained as single regioisomers without the corresponding allene adducts observed.     

First lipase catalysed resolution of epoxy enol esters

We report the first enzyme-catalysed kinetic resolution of epoxy enol esters. The lipase-promoted hydrolysis of these compounds provided α-hydroxyketones or α-hydroxyaldehydes (arising from the spontaneous rearrangement of the epoxy enols) and the residual esters with moderate to good enantioselectivity (E up to 100).