Aryltellurium Trichlorides Research Articles

INTERACTION OF 4-(ALLYLOXY)-5,6-DIMETHYL-2-(THIOPHEN-2-YL)THIENO[2,3-d]PYRIMIDINE WITH TELLURIUM-CONTAINING ELECTROPHILIC REAGENTS

The chemistry of tellurium-containing electrophilic reagents remains less explored and studied compared to other chalcogen-containing electrophiles. This study investigates the interaction of tellurium tetrahalides and p-methoxyphenyltellurium trichloride with 4-(allyloxy)-5,6-dimethyl-2-(thiophen-2-yl)thieno[2,3-d]pyrimidine. It was found that reactions with in situ generated tellurium tetrahalides in glacial acetic acid lead to the formation of adducts with a 1:1 composition of 4-(allyloxy)-5,6-dimethyl-2-(thiophen-2-yl)thieno[2,3-d]pyrimidine-tellurium tetrahalide, confirmed by ¹H NMR spectral data and elemental analysis. Reactions between 4-(allyloxy)-5,6-dimethyl-2-(thiophen-2-yl)thieno[2,3-d]pyrimidine and p-methoxyphenyltellurium trichloride in glacial acetic acid also yielded adducts of an identical composition, indicating that substituting tellurium tetrachlorides with aryl tellurium trichloride does not alter the reaction’s outcome. Experimental data demonstrate that the nature of the electrophilic reagent does not affect the reaction path, enabling regioselective formation of 1:1 substrate-electrophile adducts.

Synthesis of 1,3-benzotellurazole derivatives from phenyl ureas and tellurium tetrachloride

A method has been developed to prepare previously inaccessible substituted 1,3-benzotellurazoles following an efficient two-step process, consisting of the tellurination of electron rich phenyl ureas with tellurium tetrachloride and subsequent ring closure of the resulting aryl tellurium trichlorides. Tellurination occurs regiospecifically ortho to the urea moiety due to intramolecular Te–O coordination, producing highly crystalline solids that are readily isolated in yields up to 83 %. Subsequent ring closure, accomplished by heating with phosphorus trichloride and subsequent reduction with hydrazine hydrate, provides access to 1,3-benzotellurazole derivatives. Selected products were characterized by X-ray crystallography.

REGIOSELECTIVITY OF THE TELLURIUM-INDUCED CYCLISATION OF TERMINALLY SUBSTITUTED ALLYL, BUTENYL AND PROPARGYL THIOETHERS OF THIENOPYRIMIDINE

The method of electrophilic intramolecular cyclization is widely used for the synthesis of condensed thienopyrimidine derivatives. In this work, the regioselectivity of the process of electrophilic intramolecular cyclization of terminally substituted allylic derivatives, but-1-enyl and propargyl thioethers of thienopyrimidine with p-methoxyphenyltellurttrichloride was investigated.
 It was established that as a result of the tellurium-induced cyclization of butenyl thioethers of 5,6-dimethyl-3-phenylthieno[2,3-d]pyrimidin-4(3H)-one with p-methoxyphenyltellurium trichloride, angular tricyclic chlorides ― 8-(dichloro(4-methoxyphenyl)-tellanyl)-2,3,9-trimethyl-4-oxo-5-phenyl-5,7,8,9-tetrahydro-4H-thieno[3',2':5,6]pyrimido[2,1-b][1,3]thiazine-10-ium and 9-((dichloro(4-methoxyphenyl)-tellanyl)methyl)-2,3-dimethyl-4-oxo-5-phenyl-5,7,8,9-tetrahydro-4H-thieno­[3',2':5,6]pyrimido[2,1-b][1,3]thiazine-10-ium with an annealed six-membered ring in the form of complexes with p-methoxyphenyltellurium trichloride. It was proved that the electrophilic intramolecular cyclization of 5,6-dimethyl-2-(prop-2-yn-1-ylthio)-3-phenylthieno[2,3-d]pyrimidin-4(3H)-one with aryltellurium trichloride occurs with the formation of an aryltellurium trichloride complex with angular chloride 8-((dichloro(4-methoxyphenyl)-tallanyl)methylidene)-2,3-dimethyl-4-oxo-5-phenyl-4,5,7,8-tetrahydrothiazolo[3,2-a]thieno [3,2-e]pyrimidin-9-ium in the form of one geometric isomer.
 Keywords: electrophilic heterocyclization; p-methoxyphenyltellurium trichloride; organotellurium compounds; chloride 4H-thieno[3',2':5,6]pyrimido[2,1-b][1,3]thiazine-10-ium; chloride 4H-thieno[3',2':5,6]pyrimido[2,1-b][1,3]thiazine-10-ium; chloride thiazolo[3,2-a]thieno[3,2-e]pyrimidin-9-ium.

TELLURO-INDUCED CYCLISATION 2-(BUT-2-ENYLTHIO)QUINOLINECARBALDEHYDE AND QUINOLINE-4-ONE

Aryltellurium trichlorides have proven themselves as good cyclizing reagents in electrophilic intramolecular cyclization reactions, mainly of propenyl derivatives of heterocycles. On the other hand, information on the use of butenyl derivatives in reactions with p-alkoxyphenyltellurtrichlorides is limited. In this work, the regioselectivity of the process of electrophilic intramolecular cyclization of but-2-enyl thioethers of quinoline-3carbaldehyde and quinazolin-4-one with p-methoxyphenyltellurium trichloride was investigated.
 It was established that, as a result of the tellurium-induced cyclization with p-methoxyphenyltellurium trichloride of but-2-enyl thioethers of quinoline and quinazoline, angular tricyclic chlorides – 2-(dichloro(4-methoxyphenyl)-tellanyl)-1-methyl-5-formyl-2,3- dihydro-1H-[1,3]thiazino[3,2-a]quinolin-11-ium and 2-(dichloro(4-methoxyphenyl)-tellanyl)-1-methyl-6-oxo-5-phenyl-2, 3,5,6-tetrahydro-1H-[1,3]thiazino[3,2-a]quinazolin-11-ium, respectively, with an annealed six-membered ring in the form of complexes with p-methoxyphenyltellurium trichloride. Optimal conditions for the electrophilic intramolecular cyclization reaction were selected.
 Keywords: electrophilic heterocyclization; p-methoxyphenyltellurium trichloride; organotellurium compounds; chloride 2-(dichloro(4-methoxyphenyl)-tellanyl)-1-methyl-5-formyl-2,3-dihydro-1H-[1,3]thiazino[3,2 -a]quinolin-11-ium, chloride 2-(dichloro(4-methoxyphenyl)-tellanyl)-1-methyl-6-oxo-5-phenyl-2,3,5,6-tetrahydro-1H-[1,3]thiazino[3,2-a]quinazolin-11-ium

ARYLTELLUROCHLORINATION OF N-ALLYLTHIOAMIDE OF TRIFLUOROACETIC ACID

Telluroganic compounds have a pronounced biological activity, namely, show antitumor, antioxidant, antiparasitic activity. The introduction of a trifluoromethyl group to such compounds can significantly increase the activity. Therefore, the aim of this study is the synthesis of tellurium-containing compounds by the electrophilic action of aryltellurium trichloride on N-allylthioamide of trifluoroacetic acid.
 As the object of the study of the aryltellurohalogenation process of N-allyl thioamide of trifluoroacetic acid was chosen. The selection is dictated by the presence of several nucleophilic centers suitable for the attack by electrophiles and can form both addition and cyclization products. The synthesis of the amide was performed through the interaction of ethyl ester of trifluoroacetic acid with allylamine in tetrahydrofuran followed by the treatment of the formed N-allylamide with phosphorus (V) sulfide in the presence of hexamethyldisiloxane in toluene.
 Propargyl trifluoroacetic acid amide was investigated in the halogenation reaction, which resulted in the addition product. It was important to establish the effect of the nature of the unsaturated alkenyl/alkynyl substituent, the additional nucleophilic center and the electrophilic reagent on the reaction pathway. The reaction of N-allyltrifluorothioacetamide with p-methoxyphenyltellurium trichloride was performed in chloroform or tetrahydrofuran at room temperature in equimolar amounts of reagents. The addition product N-(2-chloro-3- (dichloro (4-methoxyphenyl) -)-l4-4-tellanyl)propyl] -2,2,2-trifluoroethanethioamide was obtained. Similar addition products were formed in the reaction of N-allyl thioureas with aryltellurium trihalides.

ELECTROPHILE CYCLIZATION OF N (S, Se)-ALKENYL DERIVATIVES OF PYRIMIDINONE WITH p-METOXYPHENYLTELLURIUM TRICHLORIDE

Pyrimidinone is a component of bioactive natural compounds such as uracil, thymine and cytosine. Pyrimidinone derivatives exhibit antitumor, antiviral and psychotropic properties. The heterocyclization of unsaturated pyrimidinetione derivatives produces condensed azolopyrimidines, which also exhibit a wide range of biological activity. The introduction а tellurium atom into such systems can increase their bioactivity. One of the most convenient and straightforward methods for introducing a tellurium atom is the electrophilic intramolecular cyclization method.The interaction between synthesized for the first time 3-methyl-2-thioxopyrimidin-4-one and p-methoxyphenyltellurium trichloride was carried out in glacial acetic acid at room temperature. It has been established that the electrophilic intramolecular cyclization of N-methallyl 2-thioxopyrimidine-4-one p-methoxyphenyltellurium trichloride takes place with the participation of a sulfur atom with the anelation of the thiazoline cycle to the pyrimidine system. As a result of reaction received 2,7-Dimethyl-2-{[dichloro(4-methoxyphenyl)-telluro]methyl}-2,3-dihydro-5H-[1,3]thiazolo[3,2-a]pyrimidine-5-one hydrochloride.The regioselectivity of the process of electrophilic cyclization with aryltelluriumtrichlotide was investigated on 2-S-alkenyl derivatives of 6-methylpyrimidin-4-one. It is shown that the reaction between aryltellurium trichloride and 2-thioalkenyl derivatives of 6-methylpyrimidin-4-one results in the formation of cyclization products with the involvement of a nitrogen atom at the third position of the pyrimidine. It is revealed that tellurofunctionalized thiazolinopyrimidines are formed in the form of complexes with aryltellurium trichloride. To study the effect of chalcogen on the regioselectivity of the process of electrophilic cyclization in reaction with p-methoxyphenyltellurium trichloride, a metalyl selenoether of 6-methylpyrimidin-4-one was used. It has been proved that 2-Se-methallyl N-1,3-unsubstituted pyrimidinone is cyclized by aryltellur trichloride to form a selenazolinopyrimidine system, which in turn allows to obtain potentially biologically active heterocycles with an endocyclic Selenium atom and an exocyclic Tellurium atom. The nature of chalcogen does not affect the direction of electrophilic intramolecular cyclization. The structure of obtained compounds were proved by NMR spectroscopy, IR spectroscopy and elemental analysis.

Reactions of N‐alkenyl Thioureas with p‐alkoxyphenyltellurium Trichlorides

N‐Аlkenyl thioureas, under the action of aryltellurium trichlorides, form the addition products N‐{2‐chloro‐3‐[dichloro(4‐alkoxyphenyl)‐tellanyl]propyl} thioureas or the intramolecular cyclization products 5‐{dichloro(4‐alkoxyphenyl)‐telluromethyl}‐2‐phenylamino‐4,5‐dihydro‐1,3‐thiazole hydrochlorides. The reaction route depends on the nature of the substituent in the thiourea. The Fukui function reactivity indexes identify the electrophilic/nucleophilic centers and explain the possible cyclization reaction in the case of phenyl substituted thioureas. In the case of other substituents, the calculated values of partial atomic charges clearly predict that the addition reaction is more possible.

INFLUENCE HALOGEN IN REACTION ARYLTELLUR TRYHALOHENIDE ELECTROPHILIC CYCLIZATION OF N-ALKENYL OF 2-TIOXOBENZO (THIENO)PYRIMIDIN-4-ONES

It is known from the literature that electrophilic heterocyclization of unsaturated substrates under the action of aryltellurium trichlorides is widely used to obtain tellurium-containing polycondensed heterocyclic systems, whereas the use of p -alkoxyphenyltellurium tribromides in such reactions is almost not described. p -Ethoxyphenyltelluriumtribromide was used for study the influence of a halogen in the electrophilic aryltelluronium reagent on products' yields and on the direction of the electrophilic intramolecular cyclization of N-alkenyl-2-thioxobenzo(thieno)pyrimidine-4-ones. It was not possible to obtain this electrophile with the reaction of tellurium tetrabromide with benzene containing electron donating group, so it was synthesized by bromination of the corresponding ditelluride in chloroform medium. The interaction between tellurium-containing electrophile and N-alkenyl-2-thioxobenzo(thieno)pyrimidine-4-ones was carried out in glacial acetic acid at room temperature. It has been established that during aryltellurobromination of 3-allyl-quinazoline-2-thione and N-alkenyl thioxo-thieno-pyrimidinones, the annelation of the thiazoline ring takes place, with the formation of a linear condensed system with an exocyclic aryltellurium fragment – hydrobromides of 3-[dibromo(4-ethoxyphenyl)telluromethyl]-2,3-dihydro-5 H -[1,3]thiazolo[2,3-b]quinazolin-5-one, 2-(dibromo(4-ethoxyphenyl)-telluromethyl)-2,3,6,7,8,9-hexahydro-5 H -benzo[4,5]thieno[2,3-d][1,3]thiazolo[3,2-a]pyrimidin-5-one and 2-methyl-2-(dibromo(4-ethoxyphenyl)-2,3,6,7,8,9-hexahydro-5 H -benzo[4,5]thieno[2,3-d][1,3]thiazolo[3,2-a]pyrimidine-5-one. The structure of the products of bromotelluro-cyclization is similar to the structure of products of aryltellurochlorination of the corresponding heterocycles. However, the yields of salts with the exocyclic bromoaryltellurium fragment are smaller compared to chloro- analogs. Lower yields of hydrobromides are associated with lower stability of intermediate bromotelluronium cation compared with chlorotelluronium, which is confirmed by theoretical calculations of Gibbs free energy of interaction of aryldihalidetellanium cation with an unsaturated substrate. Computations were performed using DFT level of theory in PRIRODA 17 program with using of GGA PBE functional and 3ζ basis set. The effect of solvent medium (acetic acid) was taken into account using the COSMO model with PM7 Hamiltonian in MOPAC2016 program. The composition and structure of all obtained compounds are proved by elemental analysis and NMR spectra.

Telluration of Alkenylmethyl Ketones with Aryltellurium Trichlorides: Synthetic Route and Structural Studies

It has been our endeavor to prepare organotellurium compounds bearing functionalized groups. The electrophilic substitution reactions were performed with 1-acetyl-1-cyclohexene, an alkenylmethyl ketone (cyclo-C6H9COCH3), with NpTeCl3 and MesTeCl3. The reactions were found to proceed smoothly at room temperature. The unsymmetrical functionalized arylalkyltellurium dichloride Np(cyclo-C6H9COCH2)TeCl2, 1Aa or Mes(cyclo-C6H9COCH2)TeCl2, 1Ba was obtained in good to moderate yield when the reactants were stirred for 7-8 h in absence of any solvent. The reaction with MesTeCl3 is rather slow and requires over 24 h of stirring. Biphasic (H2O/CH2Cl2) reduction of the dichlorides 1Aa or 1Ba with aqueous Na2S2O5 did not gave the expected unsymmetrical telluroether (cyclo-C6H9COCH2)-Te-Ar, instead the usual work up of the organic phase afforded the respective ditellurides, Ar2Te2. The bromo analogues of 1Aa and 1Ba, namely Ar(cyclo-C6H9COCH2)TeBr2 (Ar= 1-Np, 1Ab and Mes, 1Bb), were prepared by the metathetical reaction of the chlorides with sodium bromide (Scheme 1). The newly synthesized dihaloaryltellurated alkenyl carbonyl compounds are colourless to pale yellow crystalline solids soluble in common organic solvents and have been characterized by 1H, 13C and 125Te NMR in solution. The structural studies in the solid state for the compounds 1Aa and 1Ba have been carried out by single-crystal X-ray diffraction technique

Electrophilic substitution of acetyltrimethylsilane with tellurium(IV) halides: A synthetic route to 3-methyl-5-(trimethylsilyl)-1,2-oxatellurol-1-ium halides

The reaction of tellurium tetrahalides, TeX4 (XCl. Br) with acetyltrimethylsilane in CCl4 at ambient temperature, unlike that of the aryltellurium trichlorides, ArTeCl3 that give the expected electrophilic substitution products, Ar(Me3SiCOCH2)TeCl2, (Ar = 1-C10H7, 2; 2,4,6-Me3C6H2, 3), afforded novel silylated heterocycles, 3-methyl-5-(trimethylsilyl)-1,2-oxatellurol-1-ium halides 1a and 1b. These Te(II) heterocyclic compounds undergo halide exchange with sodium iodide and also add dihalogens oxidatively to afford the corresponding iodide, 1c and the Te(IV) trihalides, 5a and 5b respectively. A large lowering of ν(CO) is indicative of strong Te⋯OC interactions among these heterocycles, and is also substantiated by single-crystal X-ray diffraction data for 3-methyl-5-(trimethylsilyl)-1,2-oxatellurol-1-ium chloride. The 125Te chemical shifts for the new 10-Te-3 telluranes and 12-Te-5 pertelluranes that involve tellurium bound to two highly electronegative atoms (O, X) are among the highest (downfield) reported for organotellurium(II) and (IV) compounds.

Stereospecific chlorotelluration of terminal acetylenes

Chlorotelluration of terminal acetylenes, RCHCH (R = Ph, 1; 4-MeC6H4, 2; t-Bu, 3) with aryltellurium trichlorides and TeCl4 in refluxing toluene affords (2-chloro-2-organylvinyl)tellurium(IV) dichlorides, Ar[R(Cl)CCH]TeCl2 (Ar = 1-C10H7, 1Aa–3Aa; 2,4,6-Me3C6H2, 1Ba–3Ba; 4-MeOC6H4, 1Ca) and [t-Bu(Cl)CCH]2TeCl2, 3a respectively. These Te(IV) derivatives on reduction with Na2S2O5 give the corresponding vinyltellurides as oils, except (2,4,6-Me3C6H2)[Ph(Cl)CCH]Te (1B) which is a crystalline solid. The dibromides (1Ab–3Ab, 1Bb–3Bb, 3b) and diiodides (1Ac–3Ac, 1Bc–3Bc, 1Cc) were obtained by the oxidative addition of dihalogens to the tellurides. The stereochemistry of the products has been established with the help of X-ray diffraction studies of 1Aa, 1Ba, 1Bc, 1Cc, 3Aa, 3a and 1B. Intramolecular Te⋯Cl attractive interactions appear to favor the (Z) conformation adopted by the 2-chloro-2-organylvinyltellurium group irrespective of the steric demand of the aryl ligand of the Te(IV) electrophile and the terminal acetylene substituent. The intermolecular Te⋯X secondary bonding interactions give rise to dimeric units in the lattices of 1-naphthyl- and anisyltellurium(IV) derivatives, but are absent among the mesityl analogues, consistent with the larger steric requirement of the latter ligand.

Controlled hydrolysis of aryltellurium trichlorides using 2-pyrrolidinones: isolation and structural characterization of monomeric aryltellurium(IV) monohydroxides

The 2-pyrrolidinone (Pyrr)-assisted hydrolysis of aryltellurium trichlorides, provided their first-step hydrolysis products as 1 : 1 molecular adducts, ArTeCl2OH.Pyrr (Ar = 1-C10H7, Npl, 1; 2,4,6-Me3C6H2, Mes, 2). The hydroxo ligand occupies an equatorial position in the ψ-trigonal bipyramidal geometry around Te(IV) and is involved in a strong H-bonding interaction with the amido O of the base. As NplTeBr3 did not react with 2-pyrrolidinone under similar conditions, the bromo analogue of 1, NplTeBr2OH.Pyrr (3), was prepared by a metathetical reaction with NaBr. Both 1 and 2 undergo electrophilic substitution with acetone and pinacolone to afford Ar(RCOCH2)TeCl2 (R = Me, t-Bu), but do not react with iodoacetic acid, suggesting that the hydroxo ligand acts as a nucleophile rather than a base. The Te–OH bond in 1 is also cleaved by CH3COCl to give the parent trihalide NplTeCl3, while reaction with BrCH2COBr results in NplTeBr3 (4) as the ultimate tellurium containing product. The reaction of NplTeCl3 with N-Methyl protected 2-pyrrolidinone (PyrrMe), under similar conditions, gave an ionic complex [(PyrrMe)2H] [NplTeCl4] (5), but did not react with N-acyl protected 2-pyrrolidinone, PyrrCOCH2Br. However, the latter added oxidatively to elemental tellurium to give (PyrrCOCH2)2TeBr2 (6). In the crystal lattice of 5, discreet five-coordinate square pyramidal CTeX4 units are present, while in the case of 4 the same units are realized via intermolecular Te⋯Br interactions in a one-dimensional supramolecular architecture. N-(2-pyrrolidinone)amidomethyl ligands in 6 adopt a rare, if not the first, 1,6-(C,O) mode of chelation in preference to 1,4-(C,O) mode often observed in similar Te(IV) compounds.

Intramolecularly Coordinated Telluroxane Clusters and Polymers

The stoichiometrically controlled chlorination of the diarylditelluride (8-Me(2) NC(10) H(6) Te)(2) with SO(2) Cl(2) afforded the aryltellurinyl chloride 8-Me(2) NC(10) H(6) TeCl (1) and the aryltellurium trichloride 8-Me(2) NC(10) H(6) TeCl(3) (2). Alternatively, 1 was obtained by the reaction of the aryltellurenyl diethyldithiacarbamate 8-Me(2) NC(10) H(6) Te(S(2) CNEt(2) ) with hydrochloric acid. The base hydrolysis of 2 provided the novel telluroxanes (8-Me(2) NC(10) H(6) Te)(2) OCl(4) (3), (8-Me(2) NC(10) H(6) Te)(6) O(5) Cl(8) (4), (8-Me(2) NC(10) H(6) Te)(6) O(8) Cl(2) (5), [(8-Me(2) NC(10) H(6) Te)(2) O(3) ](n) (6) and (8-Me(2) NC(10) H(6) Te)(6) O(8) (OH)(2) (7) depending on the reaction conditions applied. The reaction of 7 with ClTe(OiPr)(3) in the presence of water gave rise to the telluroxane (8-Me(2) NC(10) H(6) Te)(6) Te(2) O(12) Cl(2) (8). The crystal and molecular structures of 1-3 and 5-8 were determined by X-ray crystallography. The telluroxane clusters and polymers 6-8 hold potential as model compounds for alkali tellurite glasses (M(2) O)(x) (TeO(2) )(1-x) (M=Li, Na, K) for which no precise structural data are available.

ChemInform Abstract: Cyclization of Olefinic Benzyl Ethers with Aryltellurium Trichlorides.

Abstract Olefinic benzyl ethers react with aryltellurium trichlorides leading to tetrahydrofurans in high yields. The reaction times and yields are similar to the analogous cyclization of the corresponding olefinic alcohols. The stereoselec-tivity of the transformation is low.

α-Telluration of 2,4,6-trimethylacetophenone under mild conditions: Role of steric factor in the solid state structures of Te(II and IV) compounds

Elemental tellurium inserts into the C sp3–Br bond of α-bromomesitylmethyl ketone and due to its strong carbophilic character affords the crystalline C-tellurated derivative of 2,4,6-trimethylacetophenone, (MesCOCH 2) 2TeBr 2, 1b in over 80% yield. Electrophilic substitution of the parent ketone with aryltellurium trichlorides, at room temperature, gives nearly quantitative yields of unsymmetrical alkylaryltellurium dichlorides (MesCOCH 2)ArTeCl 2 (Ar = mesityl, Mes, 2a; 1-naphthyl, Np, 3a; anisyl, Ans, 4a). Fairly stable mesitoylmethyltellurium(II) derivatives, (MesCOCH 2) 2Te, 1 and (MesCOCH 2)ArTe (Ar = Mes, 2; Np, 3 and Ans, 4) obtained as the reduction products of their dihalotellurium(IV) analogues, readily undergo oxidative addition of dihalogens to afford the corresponding (MesCOCH 2) 2TeX 2 (X = Cl, 1a; Br 1b; I, 1c) and (MesCOCH 2)ArTeX 2 (X = Cl, Br, I, Ar = Mes, 2a, 2b, 2c; Np, 3a, 3b, 3c and Ans, 4a, 4b, 4c). Crystallographic structural characterization of 1, 1b, 2, 2a, 2b, 2c, 3, 3a and 4c illustrates that the steric demand of mesityl group appreciably influences primary geometry around the 5-coordinate Te(IV) atom when it is bound directly to it. It also makes the Te atom inaccessible for the ubiquitous Te⋯X intermolecular secondary bonding interactions that result in supramolecular structures. In the crystal lattice of symmetrical telluroether 1, an interesting supramolecular synthon based upon reciprocatory weak C–H⋯O H-bonding interaction gives rise to chains via self-assembly.

Acylmethyl(aryl)tellurium(iv,ii) derivatives: intramolecular secondary bonding and steric rigidity

Electrophilic substitution of acylmethanes (methyl ketones), RCOCH3 (R = i-Pr, 1; Et, 2; Me, 3) with aryltellurium trichlorides, ArTeCl3 (Ar = 1-C10H7, Np, A; 2,4,6-Me3C6H2, Mes, B; 4-MeOC6H4, Anisyl, C) under mild conditions affords the corresponding acylmethyl(aryl)tellurium dichlorides (RCOCH2)ArTeCl2. Reduction of the dichlorides, gives tellurides, (i-PrCOCH2)ArTe, 1A-1C, which give the corresponding dihalides, (i-PrCOCH2)ArTeX2 (X = Cl, 1Aa-1Ca; Br, 1Ab-1Cb; I, 1Ac-1Cc) when reacted in situ with SO2Cl2, Br2 or I2. The unsymmetric tellurides are labile towards disproportionation and attempts to obtain them lead to the isolation of Ar2Te2 except in the case of (i-PrCOCH2)MesTe (1B), which represents an interesting example of a kinetically stable aryl(alkyl)telluride. All the dihalomesityltellurium(IV) derivatives show separate 1H and 13C NMR signals for the ortho methyls irrespective of the sizes of R and X ligands. The telluride, 1B with free rotation about Te-C(mesityl) bond shows, like the unsymmetric diorganotellurium(IV) dihalides, only one 125Te NMR signal. The 1,4-chelating behavior of the acyl ligand among diorganotellurium(IV) compounds is inferred from the X-ray diffraction data for 1Aa, 1Ac, 1Ba, 1Bb, 1cA and 1Cc which are indicative of the presence of intramolecular Te...O secondary bonding interactions (SBIs) at least in the solid state. As a consequence, steric repulsion in case of the mesityltellurium(IV) derivatives, 1Ba and 1Bb, reaches the threshold so as to cause loss of two-fold rotational symmetry of the mesityl group about the Te-C(mesityl) bond axis. Intermolecular C-HO...O H-bonding interactions appears to stabilize such an orientation of the aryl ligand at least in the solid state.

One-Pot Synthesis of Aryl Butyl Tellurides from Tellurium Tetrachloride and Activated Aromatics Through a Solventless Step.

A solventless preparation of aryl tellurium trichlorides from activated aromatic compounds avoiding the use of hazardous solvents as carbon tetrachloride and chloroform is described. The trichlorides were reduced and alkylated leading to aryl butyl tellurides in a one-pot procedure. Transmetallation of these tellurides with n-butyllithium followed by reaction with benzaldehyde gave the corresponding benzhydrols in good yields.

One-pot synthesis of aryl butyl tellurides from tellurium tetrachloride and activated aromatics through a solventless step

A solventless preparation of aryl tellurium trichlorides from activated aromatic compounds avoiding the use of hazardous solvents as carbon tetrachloride and chloroform is described. The trichlorides were reduced and alkylated leading to aryl butyl tellurides in a one-pot procedure. Transmetallation of these tellurides with n-butyllithium followed by reaction with benzaldehyde gave the corresponding benzhydrols in good yields.

Facile access to aryltellurium compounds from arylboronic acids

Arylboronic acids were treated with tellurium tetrachloride to generate substituted aryltellurium trichlorides, which were reduced to the corresponding diaryl ditellurides in good to excellent overall yields. Representative products include diphenyl ditelluride, bis(2-nitrophenyl) ditelluride, bis(3-nitrophenyl) ditelluride, bis(4-methylphenyl) ditelluride and bis(2-chlorphenyl) ditelluride. 3,5-Dimethylphenyl 2′-nitrophenyl telluride and 3,5-dimethylphenyl 3′-nitrophenyl telluride were prepared in analogous fashion, in modest yields, from 3,5-dimethylphenyltellurium tribromide and the corresponding nitrophenylboronic acids.

The Influence of the Substrate Structure in the Tellurocyclofunctionalization Reaction of <FONT FACE=Symbol>g,d</FONT>-Unsaturated Carboxylic Acids and their Corresponding Benzyl Esters

g,d-Unsaturated carboxylic acids containing monosubstituted double bonds react with aryltellurium trichlorides to give the expected tellurolactone. Reaction of the corresponding benzyl esters gives the addition product of the aryltellurium trichlorides to the double bond. g,d-Unsaturated carboxylic acids containing 1,1-disubstituted double bonds lead to a mixture of the expected tellurolactone and the product of hydrochloric acid addition to the double bond; the corresponding benzyl ester gives the tellurolactone as the only product. The stereoselectivity of the reaction is low; mixtures of the two possible diastereomeric lactones are formed in approximately 1:1 ratios.