Search

An efficient one-pot procedure has been developed for the synthesis of previously unknown 1,1′-(9-selenabicyclo[3.3.1]nonane-2,6-diyl)dipyridinium dibromides containing acetal moieties via transan-nular addition of selenium dibromide to Z,Z-cycloocta-1,5-diene, followed by reaction with pyridine-3- and 4-carbaldehyde acetals. The yields of the target products range from 80 to 97%. [ABSTRACT FROM AUTHOR]

Efficient methods for the synthesis of new fused heterocyclic compounds have been developed on the basis of annulation–functionalization of acetyl eugenol with selenium dibromide. The proposed procedures make it possible to obtain functional derivatives of dihydrobenzoselenophene and selenochroman containing bromo, methoxy, and acetoxy substituents with high yields in one preparative step. Nucleophilic substitution of bromine in 2-(bromomethyl)-5-methoxy-2,3-dihydro-1-benzoselenophen-6-ol has been found to involve ring expansion rearrangement with the formation of selenochroman derivatives. [ABSTRACT FROM AUTHOR]

One-step procedures have been developed for the selective synthesis of functionalized 2,3-dihydro-1,4-benzoxaselenines in 90–98% yields by cyclization of carvacrol allyl ether with selenium dihalides. Annulation/acetoxyselenation reaction has been performed for the first time. [ABSTRACT FROM AUTHOR]

Hitherto unknown addition and methoxyselenation reactions of selenium dihalides with methyl eugenol and allyl naphth-1-yl ether were studied. The addition and methoxyselenation reactions of selenium dihalides with methyl eugenol led mainly to Markovnikov products, while the formation of anti-Markovnikov products prevailed in the reactions with allyl naphth-1-yl ether. Families of novel functionalized selenides, including bis[3-(3,4-dimethoxyphenyl)-2-methoxy- and -2-haloprop-1-yl] selenides, bis[3-(3,4-dimethoxyphenyl)-1-methoxy- and -1-haloprop-2-yl] selenides, bis[3-(naphth-1-yl)-1-methoxy- and -1-haloprop-1-yl] selenides, bis[3-(naphth-1-yl)-2-methoxy- and -2-haloprop-1-yl] selenides, were synthesized. [ABSTRACT FROM AUTHOR]

Previously unknown functionally substituted 1,1′-(9-selenabicyclo[3.3.1]nonane-2,6-diyl)dipyridi-nium dibromides were synthesized in 90–98% yields by one-pot condensation of selenium dibromide, cyclo-octa-1,5-diene, and substituted pyridines. [ABSTRACT FROM AUTHOR]

We studied immunotropic properties of synthetic selenium-organic preparation 2,6-dipyridinium-9-selenabicyclo[3.3.1]nonyl dibromide (974zh). The experimental preparation reduced the cAMP/cGMP ratio, which indicated an increase in proliferative activity of cells of immunocompetent organs (thymus and spleen) in experimental animals. It was shown that 974zh intensified the immune response to Yersinia pestis EV thereby increasing the resistance to the plague agent. [ABSTRACT FROM AUTHOR]

Efficient methods have been developed for regioselective synthesis of new organochalcogen compounds containing 2,3-dihydro-1-benzofuran-2-ylmethyl and 7-methyl-2,3-dihydro-1-benzofuran-2-ylmethyl substituents by reactions of selenium and sulfur dichlorides and tellurium tetrachloride with 2-allylphenol and 2-allyl-6-methylphenol. [ABSTRACT FROM AUTHOR]

Selenium tetrahalides generated from selenium dioxide and hydrogen halides (HCl, HBr) reacted with hex-1-ene, hept-1-ene, and oct-1-ene at a SeO-alkene molar ratio of 1: 2 to give mixtures of dihalobis-(2-haloalkyl)-λ-selanes (yield 80-90%) and bis(2-haloalkyl) selenides (yield 5-12%). Halogenation of the resulting mixtures afforded 85-93% (calculated on the initial SeO) of the corresponding dihalobis(2-haloalkyl)-λ-selanes, and the reduction of the same mixtures with NaSO gave bis(2-haloalkyl) selenides in 80-86% yield. In the reaction with a SeO-alkene ratio of 5: 8, pure dihalobis(2-haloalkyl)-λ-selanes were formed in 84-93% yield. Dichlorobis(2-chloro-2-phenylethyl)-λ-selane was obtained in 72% yield in the reaction of SeO-HCl with styrene. [ABSTRACT FROM AUTHOR]

Alkoxyselenation of vinylbenzenes with selenium dihalides was accomplished for the first time. The reaction with selenium dibromide was the most efficient. Selenium dibromide reacted with vinylbenzene and 1-chloro-4-(prop-1-en-2-yl)benzene in chloroform or methylene chloride in the presence of methanol or ethanol to give the corresponding Markovnikov adducts, bis(2-alkoxy-2-phenylethyl) selenides and bis[2-alkoxy-2-(4-chlorophenyl)propyl] selenides in 82-95% yield with high regioselectivity. Bis(2-halo-2-phenylethyl) selenides can be obtained at low temperature (-60°C). [ABSTRACT FROM AUTHOR]

The reaction of selenium dichloride with methyl and ethyl propiolates leads to formation of anti-Markovnikov adducts. The regio- and stereoselective synthesis of hitherto unknown bis[(E)-2-chloro-1-(alkoxycarbonyl)vinyl]selenides has been developed based on this reaction. [ABSTRACT FROM AUTHOR]

Bis(2-bromo-3-hydroxypropyl) selenide was synthesized in quantitative yield by the reaction od selenium bromide with allyl alcohol. The product undergoes facile methanolysis at room temperature, which is accompanied by a rearrangement and involves substitution of bromine and hydroxy groups, located β to the selenium atom, to form bis(1,3-dimethoxypropan-2-yl) selenide and (3-hydroxy-2-methoxypropyl)(1,3-dimethoxypropan-2-yl) selenide. [ABSTRACT FROM AUTHOR]

Addition of selenium dibromide to 1-hexene, 1-octene, and allylic ethers occurs through the formation of intermediate kinetic anti-Markovnikov adducts that further transform into more thermodynamically stable Markovnikov adducts presumably via seleniranium intermediates. The methanolysis of both Markovnikov and anti-Markovnikov adducts leads to the formation of the same products in approximately the same ratio thus showing that the reaction proceeds through seleniranium intermediates. [ABSTRACT FROM AUTHOR]

We report the first study of selenium dichloride and dibromide reactions with diallyl ether, aimed at the preparation of selenium-containing heterocyclic compounds. It was established that selenium dichloride reacted regio- and stereoselectively, giving cis-3,5-bis(chloromethyl)-1,4-oxaselenane in 70% yield. Selenium dibromide gave 3,5-bis(bromomethyl)-1,4-oxaselenane in 76% yield, as a mixture of cis and trans diastereomers. The obtained compounds were used for the synthesis of previously unknown 1,4-oxaselenanes: 3,5-bis(methoxymethyl)-, 4,4-dibromo-3,5-bis(chloromethyl)-, and 3,5-bis-(bromomethyl)-4,4-dichloro-1,4-oxaselenane. The diastereomers of 3,5-bis(halomethyl)-1,4-oxa-selenanes were found to undergo unusually facile isomerization. [ABSTRACT FROM AUTHOR]

The mechanism of addition of selenium dihalides to vinyl ethers was studied at the B3LYP/6-311+G( d, p) level of theory. The reaction goes in two steps through seleniranium intermediate. High selectivity of the addition is ensured by consistent effects of the charge and orbital factors. [ABSTRACT FROM AUTHOR]

The article discusses a procedure of 2-(bromomethyl)-1,3-thiaselenole preparation by a new reaction of selenium dibromide with divinyl sulfide. It notes that the reactions occur through the formation of six-membered rings, 2,6-dihalo-1,4-thiaselenanes that underwent a rearrangement into five-membered rings, 5-halo-2-(halomethyl)-1,3- thiaselenoles, with dehydrochlorination and the formation of an endocyclic double bond resulting in 2-(halomethyl)-1,3-thiaselenoles.

The article discusses the use of 2-aryl-5-phenyl-1,4-oxaselenines as antitumor agents. It examines the reaction of selenium dichloride with allyl or propargyl phenyl in the formation of 3-chloromethyl- and E-3-chloromethylene- 2,3-dihydrobenzo[b]oxaselenines. It cites the spectrum analysis of compounds with the multiplets of the protons of the thiophene ring that signal the olefin protons.

The article explores the reactions of selenium dichloride and dibromide with an internal alkyne, hex-3-yne. The accompaniment of the addition of selenium dibromide to diphenylacetylene by electrophilic aromatic substitution leading to selenophene ring closure is discussed. The optimal conditions for the stereoselective synthesis including the use of carbon tetrachloride is also outlined.

Selenium dichloride reacted with acrylic acid, ethyl acrylate, and acrylonitrile at −20°C in a regionselective fashion to give the corresponding anti-Markovnikov adducts. This reaction was used as a basis to develop an efficient procedure for the synthesis of new functionalized selenides in nearly quantitative yields. Raising the temperature to −10°C or ambient led to loss of regioselectivity and formation of mixtures of addition products at both α- and β-positions of the double bond. [ABSTRACT FROM AUTHOR]

The article presents a study on the chemical reaction of selenium dihalides with sulfide 1. Explored is the synthesis of bis(1,4-oxathian-2-ylmethyl) selenide as well as the reaction of selenium dihalide with 2-(allylsulfanyl)-ethanol (1). Mentioned is the use of silica gel column chromatography for purifying the mixture.

The article discusses developing of selenium dihalides, new electrophilic reagents, used for introducing selenium in the structureof organic compounds [4–8]. The reaction of selenium dibromide with cyclopentene in solution in a mixture MeOH–ССl4 in the presence of Na2CO3 afforded previously unknown bis(2-methoxycyclopentyl)-selenide 1 in 96% yield and the compound 1 was proved by 1Н and13С NMR spectra. It may be used in the synthesis of new functional organoselenium compounds.

The article presents a study of the synthesis of 2-(vinylselanyl)pyridine based on nucleophilic addition of organyselenolate or selenide ions to acetylenes. It mentions the two methods used, one-pot reaction of elemental selenium with acetylene and 2-bromopyridine in a basic reducing system (BRS), KOH-DMSO (DMF, HMPA)-N2H4-H2O and the second one that is based on the reaction of acetylene with bis(pyridin-2-yl) diselenide (2) in the same basic reducing systems.

The article discusses the role of electrophilic selenium-containing reagents in the modern organic synthesis. It examines the use of electrophilic selenium in cyclization reactions for the preparation of heterocyclic compounds for the formation of new selenium-carbon bonds. It cites the reaction of selenium dibromide in tetrachloromethane at the molar ratio of the reagents.

The article discusses the study which investigates the reactions of dibromide and selenium dichloride with unsaturated chalcogenides. The study determined the 1,4-thiaselenane (I) and 1,4-thiaselenane (II) compounds on the basis of their hydrogen (H) and carbon nuclear magnetic resonance (C NMR) spectra and elemental analysis. Results show that dibromide and selenium dichloride reacted with diallyl sulfide in acetonitrile and carbon tetrachloride in regioselective fashion.

The article offers information on an experiment revealing chemical reactions of selenium bromides with butyl vinyl ether. It mentions the whole procedure along with chemicals used by scientists for this analysis. The chemical reactions obtained during the experiment have also been elaborated in detail in the article.

A letter to the editor is presented on reactions of selenium dichloride and dibromide with diallyl telluride.

The article focuses on the reaction of selenium dichloride with allyl phenyl ether, in which it resulted to heterocyclic compound such as 3-dihydro-1, 4-benzoxaselenine, and 3-chloromethyl-2. It mentions that the result was achieved through mixing the reactants in low temperature and with subsequent heating in 50-60°Celsius (C). It says that the second step electrophilic aromatic replacement requires an elevation in temperature, in which it was a region- and stereo-selective reaction.

A letter to the editor is presented regarding the addition of selenium dichloride and dibromide to propargyl halogenides to investigate the electrophilic reactions of selenium dihalogenides.

The article discusses a study aimed at using selenium dichloride and dibromide as selective electrophile reagents in synthesis of organiselenium compounds. The reactions of selenium dihalides proceed selectively to afford the target compounds in high yields in contrast to selenium tetrahalides. The results showed the possibility of annulation of the selenium-containing heterocycles to the benzene ring as evident from the reaction of selenium dichloride with unsaturated organyl phenyl ethers.

The article focuses on a study on the reaction of selenium dichloride with trimethylpropargylsilane. The reaction proceeds regio- and stereospecifically to form the Markovnikov Z,E-adduct, viz., Z,E-bis(2-chloro-3-trimethylsilylprop-1-enyl) selenide (1), in quantitative yield. The anti addition of selenium dichloride to one trimethylpropargylsilane molecule is followed by the syn addition of intermediate 2 to the second molecule.

The article focuses on the study regarding the reactions of selenium halides with unsaturated compounds. It notes the suitability of selenium dichloride and dibromide for the preparation of organoselenium compounds resulting to synthesis of diorganyldiethynylsilanes and -germanes new heterocyclic compounds. The study notes that the efficient procedure for the synthesis of selenide I opens a chance to obtain from the new functional and heterocyclic compounds.

The article focuses on the study regarding the reaction of 4-bromo-2-bromomethyl-1,3-diselenolane along with the formation of divinyl selenide. It notes the contribution of the reactions of selenium dichloride and dibromide with divinyl chalcogenides to the synthesis of new heterocyclic compounds. It examines the mechanism of formation of selenide from compound under the action of 1,8-diazabicyclo[5.4.0]undecene-7 (DBU).

The article presents a study which examines if the organic compound selenium dichloride (SD) reacts with divinyl selenide (DS) and meets the expected six-membered heterocyclic compound. It states that SD is an assuring chemical agent for organic synthesis. It also concludes that SD reacts with DS to render a five-membered heterocyclic compound with eminent selectivity, and no six-membered heterocyclic compound was discovered in the reaction mixture.

The article presents a study which examines the reactions of selenium halides and a report on the addition of selenium dibromide to divinyl sulfone. It mentions that the reaction leads to the formation of a four-member heterocyclic compound with high regio- and stereoselectivity. It also describes how selenium dibromide was generated in situ by reaction of selenium with bromine in chloroform.

Oxaselenane derivatives are obtained in reactions of diallyl ether with selenium dichloride and dibromide. [ABSTRACT FROM AUTHOR]

The article focuses on a study aimed at introducing selenium dichloride and dibromide into organic synthesis like the synthesis of 2-ethoxy-2,3-dihydro-1,4-thiaselenine leading to the rearrangement in the reaction of 2-bromomethyl-1,3-thiaselenole with ethanol. The reaction of selenium dihalides with divinyl sulfide leads to 2,6-dihalo-1,4-thiaselenanes. 2-Halomethyl-1,3-thiaselenoles is obtained by dehydrohalogenation reaction of 5-halo-2-halomethyl-1,3-thiaselenolanes in high yields.

A letter to the editor is presented in response to the article about the reaction of selenium dibromide with divinyl sulfide that was published in the previous issue.