Diaryl Tellurides Research Articles

Synthesis of Diaryl Tellurides with Sodium Aryltellurites under Mild Conditions.

A highly efficient new protocol has been developed for the formation of C-Te bonds, leading to both symmetrical and unsymmetrical diaryl tellurides. This protocol utilizes sodium aryltellurites (4), which can be easily prepared from low-cost aryltelluride trichlorides and NaOH. The synthesis involves the use of 4 and arylazo sulfones as starting materials in the presence of (MeO)2P(O)H. A variety of diaryl tellurides are obtained in moderate to good yields using this method. Importantly, this innovative protocol eliminates the need for traditional, highly toxic aryltellurolating reagents such as diaryl ditellurides and elemental tellurium. This study will bring new vitality to the synthesis of tellurides.

Synthesis of Unsymmetrical Diaryl Tellurides Under Mechanical Ball Milling in Room Temperature

Abstract: An efficient transition metal catalyst-free protocol for the synthesis of unsymmetrical diaryl tellurides has been developed by the reaction of diaryl tellurides and aryl diazonium tetrafluoroborates under mechanical ball milling in the absence of any solvent and base under room temperature. InBr (Indium Bromide) plays an important role in generating the organotelluride nucleophile via the Te-Te bond cleavage of ditelluride. A library of diaryl tellurides bearing both electron-donating and withdrawing groups in the aromatic ring has been synthesized in good to excellent yields by this protocol. Despite very high synthetic importance of diaryl tellurides in the field of organic synthesis, very few protocols have been reported to date for their synthesis. The reactions were also performed on a gram scale without any considerable change in the yields, which surely broadened the applicability of this methodology in the industrial field.

SYNTHESIS OF THIAZOLOQUINAZOLINARYLTELLURID

Symmetric and asymmetric chalcogenides of organic nature are a class of organometallic compounds that are widely used as intermediates in a number of organic reactions, as ligands in the chemistry of coordination compounds, they have a wide range of biological activity. Diaryl tellurides, which are important for the formation of new carbon-carbon bonds, have a special area in the chemistry of organotelluric compounds. The synthesis of new representatives of this class of tellurium-containing compounds is an urgent task.
 One of the main methods of obtaining of diaryl tellurides is the interaction of arylboronic acids with diarylditellurides in the presence of various metal-containing catalysts or microwave radiation. In this paper, we have considered the method of obtaining asymmetric tellurides by the reaction of reduction of sodium sulfite with salts of thiazoloquinazolinaryl dichlorotellurides without the usage of catalysts.
 It was found that the reaction of 2-((dichloro(4-methoxyphenyl)-4-tellanyl)methyl)-2,3-dihydro-5H-thiazolo[2,3-b]quinazolin-5-one hydrochloride with triple excess of sodium sulfite leads to the formation of 2-((4-methoxyphenyl)tellanyl)methyl)-2,3-dihydro-5H-thiazolo [2,3-b]quinazolin-5-one. It should be noted that the recovery does not break the bond Te-C. In the analysis of spectral data, the signals of the protons of the thiazole cycle and the exocyclic aryltelluric fragment undergo a strong field shift.
 Thus, as a result of the reduction reaction of 2-((dichloro(4-methoxyphenyl)-4-tellanyl)methyl)-2,3-dihydro-5H-thiazolo[2,3-b]quinazolin-5-one hydrochloride, a biologically promising and suitable for further functionalization telluride was received.

Transition-Metal-Free Synthesis of Unsymmetrical Diaryl Tellurides via SH2 Reaction of Aryl Radicals on Tellurium.

Although diaryl tellurides are parent organotellurium compounds, their synthesis methods, especially for unsymmetrical ones, are limited. This may be due to the instability of diaryl tellurides and their synthesis intermediates under reaction conditions. Radical reactions are known to exhibit excellent functional group selectivity; therefore, we focused on a bimolecular homolytic substitution (SH2) reaction between the aryl radical and diaryl ditelluride. Aryl radicals are generated from arylhydrazines in air and captured by diaryl ditellurides, resulting in a selective formation of unsymmetrical diaryl tellurides with high yields. The electronic effects of the substituents on both arylhydrazines and diaryl ditellurides on the SH2 reaction of tellurium are also discussed in detail.

Efficient preparation of unsymmetrical alkyl–aryl tellurides via a nickel-catalyzed reductive coupling strategy

A selective cross-coupling between unactivated alkyl bromides and diaryl tellurides through reductive nickel-catalysis is described, which efficiently led to unsymmetrical alkyl–aryl tellurides.

Silver-catalyzed synthesis of symmetrical diaryl tellurides from arylboronic acids and tellurium

The synthesis of symmetrical tellurides from different arylboronic acids and elemental tellurium using AgNO3 as a catalyst was performed.

Diorganyl tellurides as substrates in Sonogashira coupling reactions under mild conditions

A new method of Sonogashira coupling reactions between diorganyl tellurides and terminal alkynes is reported. The coupling reactions are performed using Pd(dppf)Cl2 as a catalyst, CuI as a co-catalyst in the presence of K2CO3 in DMSO. The reactions are carried out at room temperature and completed within 2 h when phenyl acetylene is used as a terminal alkyne. For aliphatic terminal alkynes, such as 1-hexyne and 1-octyne, an elevated temperature and longer reaction time are needed for the completion of the reactions. This process results in good yields of Sonogashira coupling products which is applicable for diaryl, divinyl and dialkynyl tellurides but not applicable for dialkyl tellurides.

Reaction of arylhydrazines with diaryl ditellurides in the air: Insight into bimolecular homolytic substitution on tellurium via Aryl–Te bond cleavage

AbstractThe reactivity of diaryl ditelluride and diaryl telluride toward aryl radicals was studied in detail. Diphenyl ditelluride underwent a bimolecular homolytic substitution (SH2) reaction with a phenyl radical generated from phenylhydrazine in the air, to afford diphenyl telluride in excellent yield. Based on this diphenyl telluride synthesis, a one‐pot synthesis of unsymmetrical diaryl tellurides was developed by the SH2 reaction of in situ generated diphenyl telluride with arylhydrazines in the air. The selectivity of mono‐/di‐substitution and the reactivity of arylhydrazines depend on the nature of the substituents on the arylhydrazines, that is, electron‐donating or ‐withdrawing group.

C–Te Cross-Coupling of Diaryl Ditellurides with Arylboronic Acids by Using Copper(I) Thiophene-2-carboxylate under Mild Conditions

We describe the successful cross-coupling of diaryl ditellurides with arylboronic acids by using copper(I) thiophene-2-carboxylate (CuTC) under mild conditions. Although other studies have reported that highly polar solvents (such as DMSO) or bases are required, this reaction was completed by using CuTC and common solvents under neutral conditions at room temperature. This cross-coupling reaction was performed with diaryl ditellurides and arylboronic acids bearing various groups, affording the corresponding diaryl tellurides in good to excellent yields.

Carbon-carbon bond forming reactions via Pd-catalyzed detellurative homocoupling of diorganyl tellurides

A simple and highly efficient method for the constructions of Csp-Csp, Csp2-Csp2 and Csp3-Csp3 bonds is reported. The symmetrical diaryl tellurides undergo detellurative homocouplings to afford symmetrical biaryl products. The reactions are carried out at ambient temperature using PdCl2 as a catalyst in the presence of Ag2O and Na2CO3. Similarly, the detellurative homocouplings of dibenzyl telluride and bis(phenylethynyl)telluride give bibenzyl and the conjugated diyne, respectively.

ChemInform Abstract: A Convenient and Efficient Copper‐Catalyzed Synthesis of Unsymmetrical and Symmetrical Diaryl Chalcogenides from Arylboronic Acids in Ethanol at Room Temperature.

A simple and convenient approach for the synthesis of unsymmetrical diaryl chalcogenides (Te, Se, and S) has been developed by copper-catalyzed cross-coupling reaction of organoboronic acid with diaryl dichalcogenide in ethanol using NaBH4 in air or oxygen. The present methodology is highly practical for the synthesis of unsymmetrical diaryl tellurides with various functionalities such as –NO2, –F, –Br, and –COOH that have been obtained in good to excellent yields. Methodology is also effective for the synthesis of unsymmetrical diaryl selenides and sulfides. Moreover, symmetrical diaryl selenides have also been obtained from arylboronic acids using elemental selenium powder under optimized reaction conditions. The use of NaBH4 is the key for the development of milder reaction conditions, which enable the construction of unsymmetrical diaryl chalcogenides from boronic acid substrates in ethanol at room temperature.

A convenient and efficient copper-catalyzed synthesis of unsymmetrical and symmetrical diaryl chalcogenides from arylboronic acids in ethanol at room temperature

A simple and convenient approach for the synthesis of unsymmetrical diaryl chalcogenides (Te, Se, and S) has been developed by copper-catalyzed cross-coupling reaction of organoboronic acid with diaryl dichalcogenide in ethanol using NaBH4 in air or oxygen. The present methodology is highly practical for the synthesis of unsymmetrical diaryl tellurides with various functionalities such as –NO2, –F, –Br, and –COOH that have been obtained in good to excellent yields. Methodology is also effective for the synthesis of unsymmetrical diaryl selenides and sulfides. Moreover, symmetrical diaryl selenides have also been obtained from arylboronic acids using elemental selenium powder under optimized reaction conditions. The use of NaBH4 is the key for the development of milder reaction conditions, which enable the construction of unsymmetrical diaryl chalcogenides from boronic acid substrates in ethanol at room temperature.

ChemInform Abstract: Catalyst‐Free One‐Pot Synthesis of Symmetrical Diaryl Tellurides with Te0/KOH.

AbstractIn situ generated K2Te readily reacts with various aryl iodides to give diaryl tellurides in good to excellent yields.

Telluride Catalyzed Pinacolization of Aromatic Aldehydes

The coupling reaction of aldehyde leading to pinacols was carried out by using disodium telluride and diaryl telluride in presence of potassium hydroxide in methanol solution at room temperature. These tellurides catalyze the pinacolization reactions to form α-glycols in considerable yield. All the products have been identified by comparison of their properties with those of authentic samples. It has been observed that disodium telluride is better catalyst as compare to diaryl tellurides and bis (p-methoxyphenyl) telluride is better catalyst as compared to bis(hydroxyaryl) tellurides.

Catalyst free one-pot synthesis of symmetrical diaryl tellurides with Te0/KOH

A highly efficient new protocol for C-Te bond formation leading to symmetrical diaryl tellurides has been developed. The synthesis employed aryl iodides and elemental tellurium as starting materials in the presence of KOH. It is a one-pot reaction without using any catalyst. Utilizing this new protocol, a variety of aryl and heteroaryl iodides are reacted with elemental tellurium to afford the corresponding diaryl tellurides in good to excellent yields.

ChemInform Abstract: Negishi Cross‐Coupling of Organotellurium Compounds: Synthesis of Biaryls, Aryl‐, and Diaryl Acetylenes.

A functional group tolerant palladium-catalyzed Negishi coupling of diaryl tellurides with organozinc has been developed. This methodology permits efficient preparation of biaryls, aryl acetylenes and diaryl acetylenes in moderate to good yields. A preliminary study to gain further insight into the reaction was performed using in situ ReactIR technology.

ChemInform Abstract: Aerobic Oxidation of Thiols to Disulfides Catalyzed by Diaryl Tellurides under Photosensitized Conditions.

AbstractIt allows an efficient access to a wide range of disulfides.

Negishi cross-coupling of organotellurium compounds: synthesis of biaryls, aryl-, and diaryl acetylenes

A functional group tolerant palladium-catalyzed Negishi coupling of diaryl tellurides with organozinc has been developed. This methodology permits efficient preparation of biaryls, aryl acetylenes and diaryl acetylenes in moderate to good yields. A preliminary study to gain further insight into the reaction was performed using in situ ReactIR technology.

Aerobic Oxidation of Thiols to Disulfides Catalyzed by Diaryl Tellurides under Photosensitized Conditions

Aerobic oxidation of thiols is efficiently catalyzed by diaryl tellurides such as bis(4-methoxyphenyl) telluride under photosensitized conditions to give the corresponding disulfides in good to excellent yields. In this catalytic system, the tellurone oligomer, produced by the reaction of a telluride with singlet oxygen, is assumed to be the active species and is capable of oxidizing 4 equiv of a thiol.

Formation of Diaryl Telluroxides and Tellurones by Photosensitized Oxygenation of Diaryl Tellurides

Aerobic oxygenation of diaryl tellurides under photosensitized conditions is investigated. Unlike Ph(2)S and Ph(2)Se, reaction of diaryl tellurides with singlet oxygen proceeds smoothly to yield diaryl telluroxides and the corresponding tellurones. The product distribution is largely affected by the substrate and the reaction conditions. In particular, the photooxygenation of bulky diaryl tellurides principally produces tellurones. The results of a series of trapping experiments suggest that the diaryl telluroxides can capture transient intermediates such as Me(2)S(+)OO(-) and Ar(2)Te(+)OO(-), generated in the singlet oxygen oxidation of chalcogenides, to yield diaryl tellurones, and therefore it may be the most potent precursors of the tellurones.