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FAPESP CNPq CAPES NAP-CatSinQ Hypervalent tellurium compounds (telluranes) are promising therapeutical agents with negligible toxicities for some diseases in animal models. The C-Te bond of organotellurium compounds is commonly considered unstable, disfavoring their applicability in biological studies. In this study, the stability of a set of telluranes composed of an inorganic derivative and noncharged and charged organic derivatives was monitored in aqueous media with H-1, C-13, and Te-125 NMR spectroscopy and high-resolution mass spectrometry. Organic telluranes were found to be remarkably resistant and stable to hydrolysis, whereas the inorganic tellurane AS101 is totally converted to the hydrolysis product, trichlorooxytellurate, [TeOCl3](-), which was also observed in the hydrolysis of TeCl4. The noteworthy stability of organotelluranes in aqueous media makes them prone to further structure-activity relationship studies and to be considered for broad biological investigations. Univ São Paulo, Inst Quim, BR-05508020 São Paulo, SP, Brazil Univ Fed ABC, Ctr Ciencias Nat & Humanas, BR-09210580 Santo Andre, SP, Brazil Univ Fed São Paulo, Inst Ciencias Ambientais Quim & Farmaceut, BR-04021001 Diadema, SP, Brazil Univ Fed São Paulo, Inst Ciencias Ambientais Quim & Farmaceut, BR-04021001 Diadema, SP, Brazil FAPESP: 2014/15962-5 FAPESP: 2015/08539-1 CNPq: 487012/2012-7 Web of Science

In this study was used two strains of marine-derived fungi ( Penicillium citrinum CBMA1186 and Trichoderma sp. CBMAI 932) and two strains of terrestrial fungi ( Aspergillus sp. FPZSP 146 and Aspergillus sp. FPZSP 152) to biotransformation bis-α,β-unsaturated ketones 1 – 2 to their corresponding 1,5-diphenylpentan-3-one ( 1a ), ( E )-1,5-diphenylpent-1-en-3-one ( 1b ), 1,5-diphenylpentan-3-ol ( 1c ), ( E )-1,5-diphenylpent-1-en-3-ol ( 1d ), 1,5-bis(4-methoxyphenyl)pentan-3-one ( 2a ), ( E )-1,5-bis(4-methoxyphenyl)pent-1-en-3-one ( 2b ) and 1,5-bis(4-methoxyphenyl)pentan-3-ol ( 2c ). The products were obtained in up to 84% conversion employing cultural broth and whole mycelia of mentioned fungi.

The search for a new, efficient, cheaper and sustainable matrix for lipase immobilization is a growing area in biotechnology. Amano lipase from Pseudomonas fluorescens was immobilized on silk fibroin spheres and used in the enzymatic kinetic resolution of halohydrins, to obtain optically active epoxides (up to 99% ee), important precursors in the synthesis of derivative antifungal azoles. This paper reinforces the versatility of silk fibroin as a support for heterogeneous catalysts.

Leishmania (Leishmania) infantum chagasi is one of the agents that cause visceral leishmaniasis. This disease occurs more frequently in third world countries, such as Brazil. The treatment is arduous, and is dependent on just a few drugs like the antimonial derivatives and amphotericin B. Moreover, these drugs are not only expensive, but they can also cause severe side effects and require long-term treatment. Therefore, it is very important to find new compounds that are effective against leishmaniasis. In the present work we evaluated a new group of synthetic amides against the promastigote and amastigote forms of L. infantum chagasi. The results showed that one of these amides in particular, presented very effective activity against the promastigotes and amastigotes of L. infantum chagasi at low concentrations and it also presented low toxicity for mammal cells, which makes this synthetic amide a promising drug for combating leishmaniasis.

The total synthesis of (−)-Blastmycinolactol, (+)-Blastmycinone, (−)-NFX-2, and (+)-Antimycinone was accomplished in few steps in high yields and ee, starting from enantiomerically enriched ( S )- Z -vinylic hydroxytellurides.

A influencia de grupos protetores na sintese regio- e estereosseletiva de teluretos vinilicos preparados a partir de BuTeNa e alcoois propargilicos e homopropargilicos demonstrou que o eter de silicio TIPS e util como grupo regio-dirigente. A aplicacao da metodologia na sintese de um fragmento do (±)-Seselidiol, um produto natural, demonstrou a aplicabilidade da metodologia desenvolvida. The influence of protecting groups on the synthesis of regio- and stereodefined vinyl tellurides derived from the reaction of BuTeNa and propargylic- or homo-propargylic alcohols showed that TIPS silyl ether is useful as a regiodirecting group. The application of the methodology to the synthesis of a fragment of (±)-Seselidiol, a natural product, demonstrated the applicability of the new methodology.

A set of tellurium amines have been evaluated in the tellurium/lithium exchange reaction. The nitrogen-containing organolithium compounds were efficiently prepared by using N-Bz tellurium amines and a mixture of n-butyllithium and lithium naphthalenide (LiNp) for performing the exchange reaction. The corresponding dianion intermediates were trapped with a wide range of electrophiles, furnishing the corresponding products in good to excellent yields. The reaction was also employed in the synthesis of phenethylamines. Um conjunto de amino teluretos foram preparados e testados em reações de troca telúrio/lítio. Os compostos de organolítio contendo nitrogênio foram facilmente preparados utilizando N-Bz teluroaminas e uma combinação de n-butillítio/naftaleto de lítio nas reações de troca. Os correspondentes intermediários dilitiados foram capturados com vários eletrófilos, levando à formação dos respectivos produtos em bons rendimentos. A reação foi empregada na síntese de fenetilaminas.

In this paper we present a general survey on the history of the selenium and tellurium chemistry in Brazil and worldwide. Neste artigo apresentamos um apanhado geral sobre a história da química do selênio e do telúrio no Brasil e no mundo

Enantiomerically pure (R)- and (S)-γ-hydroxy-organochalcogenides are prepared using poly-[R]-3-hydroxybutanoate (PHB) as the starting material.

The components of the pheromone blend of Mayetiola destructor, Drosophila mulleri, and Contarinia pisi were synthesized in high enantiomeric excess (99% ee) from a common enantiopure dianion prepared from an enantiopure hydroxytelluride.

The mechanism of the addition reaction of TeCl 4 to alkynes was indirectly established by the detection of TeCl 3 centered radicals using EPR spin trapping, ESI-MS and ESI-MS/MS characterization.

The use of whole cells of micro-organisms to bring about the biotransformation of an organic compound offers a number of advantages, but problems caused by enzymatic promiscuity may be encountered upon with substrates bearing more than one functional group. A one-pot screening method, in which whole fungal cells were incubated with a mixture of 4-methylcyclohexanone 1 and phenyl methyl sulfide 2 , has been employed to determine the chemoselectivity of various biocatalysts. The hyphomycetes, Aspergillus terreus CCT 3320 and A. terreus URM 3571, catalysed the oxidation of 2 accompanied by the reduction of 1 to 4-methylcyclohexanol 1a and, for strain A. terreus CCT 3320, the Baeyer-Villiger oxidation of 1 . The Basidiomycetes, Trametes versicolor CCB 202, Pycnoporus sanguineus CCB 501 and Trichaptum byssogenum CCB 203, catalysed the oxidation of 2 and the reduction 1 , but no Baeyer–Villiger reaction products were detected. In contrast, Trametes rigida CCB 285 catalysed the biotransformation of 1 to 1a , exclusively, in the absence of any detectable sulfide oxidation reactions. The chemoselective reduction of (±)-2-(phenylthio)cyclohexanone 3 by T. rigida CCB 285 afforded exclusively the (+)- cis -(1 R , 2 S) and (+)- trans -(1 S ,2 S ) diastereoisomers of 2-(phenylthio)cyclohexan-1-ol 3a in moderate yields (13% and 27%, respectively) and high enantiomeric excesses (>98%). Chemoselective screening for the reduction of a ketone and/or the oxidation of a sulfide group in one pot by whole cells of micro-organisms represents an attractive technique with applications in the development of synthesis of complex molecule bearing different functional groups.

Alkanethiols, selenols and tellurols are generated in situ by reaction of elemental sulfur, selenium and tellurium with commercial alkyllithiums, followed by reaction with deoxygenated water. The alkanechalcogenols react in situ with activated olefins in a Michael-type addition reaction.

Organotellurium(IV) compounds have been reported to have multiple biological activities including cysteine protease-inhibitory activity, mainly cathepsin B. As cathepsin B is a highly predictive indicator for prognosis and diagnosis of cancer, a possible antitumor potential for these new compounds is expected. In this work, it was investigated the effectiveness of organotellurium(IV) RT-04 to produce lethal effects in the human promyelocytic leukaemia cell line HL60. Using the MTT tetrazolium reduction test, and trypan blue exclusion assay, the IC50 for the compound after 24 h incubation was 6.8 and 0.35 microM, respectively. Moreover, the compound was found to trigger apoptosis in HL60 cells, inducing DNA fragmentation and caspase-3, -6, and -9 activations. The apoptsosis-induced by RT-04 is probably related to the diminished Bcl-2 expression, observed by RT-PCR, in HL60-treated cells. In vivo studies demonstrated that the RT-04 treatment (2.76 mg/kg given for three consecutive days) produces no significant toxic effects for bone marrow and spleen CFU-GM. However, higher doses (5.0 and 10 mg/kg) produced a dose-dependent reduction in the number of CFU-GM of RT-04-treated mice. These results suggest that RT-04 is able to induce apoptosis in HL60 cells by Bcl-2 expression down-modulation. Further studies are necessary to better clarify the effects of this compound on bone marrow normal cells.

Reaction of organotellurides with easily available organometallics leads to a fast and clean tellurium/metal exchange reaction, allowing the preparation of a range of functionalized organometallics with C-sp 3 , C-sp 2 , and C-sp hybridization carbanionic centers. Some synthetic applications of the tellurium/metal exchange reactions are discussed.

Edible tuberous roots of the species Arracacia xanthorrhiza and Beta vulgaris together with the associated microorganism, Candida guilliermondii, biocatalysed the reduction of several nitro-aromatic substrates to yield the respective amines, and the subsequent acetylation of the amine products to the corresponding acetamides. The enzymatic formation of acetamides has rarely been reported in association with the bioreduction of nitro groups. The biotransformation reactions catalysed by roots of A. xanthorrhiza, B. vulgaris and C. guilliermondii occurred independently of the locality of origin of the plant material. Consortiums of microorganism were isolated and identified as C. guilliermondii from A. xanthorrhiza and B. vulgaris roots. The C. guillermondii was able to catalyse the biotransformation of nitrobenzene into aniline. The acetanilide was not obtained by C. guilliermondii. The results demonstrate that roots of A. xanthorrhiza may be employed in the synthesis of amines and acetamides under very mild conditions. Moreover, the tuberous roots of these plants may have application in the bioremediation of nitro-aromatic compounds.

Enol phosphates and enol tosilates of β-dicarbonyl compounds react with lithium organoselenolates to give β-organoseleno (Z)-α,β-unsaturated carbonyl compounds. Tetrasubstituted vinylic vic-bis(organylchalcogenides) of (E)-geometry have been prepared by this method.

An efficient synthesis of the chiral cyclic secondary alcohols, trans -2-(phenylseleno)cyclohexanol 1a and cis -2-(phenylseleno)cyclohexanol 1a , was obtained by enzymatic reduction of 2-(phenylseleno)cyclohexanone 1 using whole fungal cells. Five strains of white-rot basidiomycetes were examined; Irpex lacteus CCB 196, Pycnoporus sanguineus CCB 196, Trametes rigida CCB 285, Trametes versicolor CCB 202 and Trichaptum byssogenum CCB 203. Cells of T. rigida CCB 285 gave alcohols cis -( RS )- 1a and trans -( SS )- 1a in high enantiomeric excesses (ca. 99%).

Aspergillus terreus CCT 3320 and A. terreus URM 3571 catalysed the biotransformations of organic β-hydroxyphenyl selenides through oxidation and methylation reactions. The kinetic resolution of (RS)-1-(phenylseleno)-2-propanol (1) via enantioselective oxidation produced (+)-(S)-1 in high enantiomeric excess (>99%) and in a yield of 50% as determined by product isolation. Oxidation of the R-enantiomer of 1, followed by elimination of the propyl moiety and subsequent methylation of the presumed intermediate, led to the formation of methylphenyl-selenide, which was isolated in a yield of 40%. Whole cells of A. terreus also biocatalysed transformations of diphenyldiselenide, benzeneseleninic acid, (RS)-1-(phenylseleno)-2-pentanol and (RS)-1-(phenylseleno)-3-methyl-2-butanol, but not of (RS)-1-(phenylseleno)-2-phenyl-methanol. This is the first report of the biomethylation of organoselenium compounds by whole cells of A. terreus.

This work describes a method to predict the 125Te and 13C NMR chemical shifts of diorgano tellurides based in a three-dimensional approach. For that, a collection of 150 compounds were selected from the literature and had their geometry optimized using the PM3 semi-empirical method. From this data, the structures were coded by the FOCOS program which described the chemical environment for each atom present in the structure, totalizing 1411 focos for the substances. The method developed was tested with ten diorgano tellurides not inserted in the database showing a higher accuracy in the prediction of 125Te and 13C NMR chemical shifts than those predicted by the commercial program. The chemical shifts and the statistical parameters obtained in this work demonstrate that the method applied was able to predict successfully the 13C and 125Te NMR chemical shifts of the diorgano tellurides. Esse trabalho descreve um método para previsão dos deslocamentos químicos de RMN de 125Te e 13C de diorgano-teluretos baseado em uma abordagem tridimensional. Para tanto, 150 substâncias foram selecionadas da literatura e tiveram suas respectivas geometrias otimizadas através do método semi-empírico PM3. A partir desses dados, as estruturas foram codificadas através do programa FOCOS, que descreve o ambiente químico de cada átomo presente na estrutura, num total de 1411 focos para as substâncias. O método descrito foi testado com dez diorgano teluretos não inseridos na base de dados e mostrou uma exatidão maior na previsão de deslocamentos químicos de RMN de 125Te e 13C do que os dados previstos por um programa comercial. Os dados e os parâmetros estatísticos obtidos nesse estudo demonstram que o método aplicado foi capaz de prever com sucesso os deslocamentos químicos de RMN de 125Te e 13C dos diorgano teluretos.

Mannich base derivatives 1–3 were biotransformed through tandem enzymatic reactions by using several microorganisms isolated from Brazilian biomes. The hydrochlorides 1 and 3 produced propiophenone 1a, α,β-unsatured ketone 2c and alcohol (S)-1b (yield 40%, e.e. 81%, Aspergillus terreus). The hydrochloride 2 underwent the Baeyer–Villiger oxidation producing exclusively para-methoxy-phenol by A. terreus and A. niger. The propiophenone 1a was reduced to their corresponding enantiomerically enriched phenylpropanol (S)-1b (yield 65%, e.e. 81%, A. terreus). The para-methoxy-propiophenone 2a afforded Baeyer–Villiger reaction hydrolyzed product, the para-methoxy-phenol (yield 80%, A. terreus). The racemic phenylpropanols 1b,2b were resolved by lipase-catalyzed kinetic resolution (Novozym 435) affording (S)-alcohols 1b,2b and (R)-acetates 1d,2d in high enantiomeric excesses (up to 99%) and good yields (40–45%). We screened new microorganisms in biotransformation of Mannich bases, propiophenones and applied enzymatic resolution of phenylpropanols by Candida antarctica lipase.

Tellurium tetrachloride adds to alkynes via two pathways: a concerted syn-addition that yields Z-tri- and -tetrasubstituted alkenes or an anti-addition that yields E-alkenes. The mechanistic aspects of these divergent pathways for TeCl4 addition to alkynes have been investigated by on-line electrospray ionization (tandem) mass spectrometry (ESI-MS(/MS)). Via ESI-MS(/MS), we have been able to intercept and characterize the active electrophile TeCl3+ in tetrahydrofuran (THF) solutions of TeCl4, as well as its THF complex and several TeClx(OH)y+ derivatives. For the first time, also, key Te(IV) cationic intermediates of the electrophilic addition of TeCl4 to alkynes were captured for gas-phase MS investigation. The detailed structural data of cyclic tellurane intermediates intercepted herein seems to provide insights into the coordinative behavior of the Te(IV) atom and its mode of action towards biological targets.

The tellurium nuclear magnetic resonance spectrum of chiral tellurium ferrocene 2 produces a single signal at different chemical shifts when solubilized together with different enantiomeric proportions of chiral compounds.

Tellurium tetrachloride adds to alkynes via two pathways: a concerted syn addition, that yields Z-tri- and tetra-substituted alkenes or by an anti addition that yields E-alkenes. The mechanistic aspects of these divergent pathways have been reevaluated at the light of crystallographic data. The molecules, of the title compound, in the crystal, are associated in a helical fashion with a Te...Te pitch of 6.3492(6) angstrom. As it exhibits inhibitory activity for cathepsin B and in order to gain more insight of the inhibition mechanism, a docking study was undertaken providing insight on why organic telluranes are more efficient inhibitors than inorganic ones as AS-101. (c) 2006 Elsevier B.V. All rights reserved.

The first experimental evidence for the formation of an organic tellurium-centered radical (RTe•, R = Ph or nBu groups) during the hydrotelluration of alkenes and alkynes is provided. The radicals were detected by electronic paramagnetic ressonance (EPR), using DBNBS (3,5-dibromo-4-nitrosobenzenesulfonate) as the spin trap. The radical adducts (DBNBS/•TenBu and DBNBS/•TePh) presented an EPR spectrum characterized by a triplet of triplets due to one nitrogen and two equivalent hydrogen atoms (aN = 21.6 G and aH = 0.7 G) and a g value of 2.0060. The presence of tellurium radical adducts was confirmed by isotopic substitution (125Te) and by electrospray and chemical ionization mass spectrometry and MS/MS analysis. The products showed isotopic patterns expected for compounds containing Br and Te. These results provide evidence for organic tellurium-centered radical formation and suggest that the hydrotelluration reactions occur by a free radical mechanism.

The enzymatic resolution of racemic mixtures of hydroxy tellurides with a range of lipases has been investigated. Lipase-B from Candida antarctica (CALB) gave the best conversions, providing both enantiomers with high enantiomeric purity. A comparative study of the effect of solvent and substrate on the enzymatic kinetic resolution was performed.

Bioreduction of acetophenone derivatives 1a – e and biooxidation of ( RS )-1-phenylethanol derivatives 2a – e have been evaluated using edible plants as biocatalysts. Chiral ( R )- and ( S )-alcohols were prepared by different plants in up to 98% of enantiomeric excess. Ketones can also be prepared from alcohol oxidation using this clean protocol.

The action of different fungal strains and hydrolytic enzymes on the biotransformation of ethyl acetate constituent of laboratory wastes (mixtures of ethyl acetate–hexanes) was investigated. The studies using Aspergillus terreus SSP 1498 as biocatalyst, showed good results concerning the efficiency of ethyl acetate biotransformation (upto 99%) and quickness of the process (5 min). Novozym 435 was found to be the best lipase for the hydrolysis of ethyl acetate from the waste (85% biotransformation).

Application of 21 new bacterial strains from natural environments (coastal plain of Santos and Atlantic Rain Forest, Sao Paulo, Brazil) in the asymmetric reduction of acetophenone derivatives is described. The bioreduction was carried out with whole bacterial cells leading to (S)-chiral alcohols in up to ≥99% e.e. The (S)-(−)-1-(2-bromo-phenyl)-ethanol was employed in the preparation of chiral tellurium derivatives.

The potential of different Aspergillus strains in carrying out the biotransformation of cyclic ketones was investigated. All the strains employed showed alcohol dehydrogenase and Baeyer–Villiger monooxygenase activities. trans -2-Methylcyclohexanol and trans -4-methylcyclohexanol were prepared in a single isomeric form by the use of Aspergillus terreus SSP 1498 and the corresponding ketones. Baeyer–Villiger oxidation of cyclic ketones by all the fungi Aspergillus led to chiral lactones in good enantioselectivity.

White-rot Basidiomycetes promoted the oxidation of aromatic pro-chiral sulfides into sulfoxides with good enantioselectivity, conversion and a small production of sulfones. The reactions were carried out using whole cells of Irpex lacteus, Pycnoporus sanguineus, Trichaptum byssogenum, Trametes rigida, Trametes versicolor and Trametes villosa. The enantioselectivity for all the aryl alkyl sulfoxides was in favor of (S)-enantiomers. Oxidation of (phenylpropyl)sulfide produced (S)-(phenylpropyl)sulfoxide with high enantiomeric excess (e.e. ≥99%) by all the Basidiomycetes employed. Basidiomycetes isolated from Brazilian biomes were used as biocatalysts in the oxidation reaction.

A series of common organometallic reagents were used in the reaction with an acyclic and a cyclic activated 2-alkenyl aziridines and the selectivity aspects for each aziridine was addressed.

Kinetic resolutions of a number of β-hydroxy selenides promoted by enzymes were performed using PPL (free Porcine pancreatic lipase), PSL (Amano PS—free Pseudomonas sp. lipase) and CALB (NOVOZYM 435 ® —immobilized Candida Antarctica lipase type B) with ( RS )-1-phenylselanyl-propan-2-ol. CALB gave the best results and provided both ( R )- and ( S )-enantiomers in high enantiomeric purity. A comparative study of the effect of temperature, solvent, enzyme immobilization and the structure of the substrates on the resolution is presented.

Experimental conditions using whole cells to select fungal strains for specific bioreduction of ketones and formation of Baeyer–Villiger oxidation products were studied. Epicoccum nigrum SSP 1498 was effective in the bioreduction leading to the chiral alcohols in up to 98% enantiomeric excess. High acetophenone monooxygenase activity was observed by the use of the fungus Emericella nidulans CCT 3119 as biocatalyst.

A series of novel organoseleno acetophenones (3a–f) have been synthesized. The microbial reduction of the seleno ketones (3) has been evaluated using whole cells of Rhizopus oryzae CCT 4964, Aspergillus terreus CCT 3320, A. terreus CCT 4083 and Emericella nidulans CCT 3119. These microorganisms showed Prelog and anti-Prelog stereoselectivity, leading to the arylselenoalcohols in moderate to high enantiomeric excesses. The organoselenium compounds were compatible with the biocatalytic conditions employed.

The enantioselective deracemization of a number of p-substituted aryl ethanols and the reduction of p-substituted acetophenones were carried out with whole fungal cells of Aspergillus terreus CCT 4083, A. terreus CCT 3320 and Rhizopus oryzae CCT 4964 giving the corresponding alcohols in enantiomeric excesses up to >99%.

C15Cl3H19O2Te, Mr = 465.25, (1), P21/a, a = 9.8303(9), b = 17.492(2), c = 10.911(1) Å, β = 108.521(8)°, Z = 4, R 1 = 0.0274. (2), P21/c, a = 8.2661(9), b = 22.863(2), c = 9.828(1) Å, β = 108.894(8)°, Z = 4, R 1 = 0.0379. In both compounds, the primary geometry of the TeIV atom is a pseudo-trigonal-bipyramidal arrangement with two halide atoms in apical positions and a lone pair of electrons and C atoms in the equatorial plane. In (1), the TeIV atom is involved in an intermolecular secondary interaction resulting in the self-assembly of a chain-like supramolecular array. In (2), molecules are linked in centrosymmetric dimers through Cl···H–O interactions.

Lithium diallylcyanocuprates generated by reaction of allyl halides with lithium n-butyltellurolate followed by transmetalation with lithium dibutylcyanocuprate react with vinyl triflates leading to highly unsaturated hydrocarbons.

The enantioselective bioreduction of a number of fluoroacetophenones was carried out with whole cells of Rhizopus oryzae CCT 4964, Aspergillus terreus CCT 3320 and Aspergillus terreus CCT 4083 giving the corresponding alcohols in good yield and high enantioselectivity. Initial results with these fungi indicated that some of them are promising biocatalysts for deracemization reactions of secondary alcohols.

This review presents the recent research in biocatalysis and biotransformation in Brazil. Several substrates were biotransformed by fungi, bacteria and plants. Biocatalytic deracemization of secondary alcohols, oxidation of sulfides, sp(3) CH hydroxylation and epoxidation of alkenes were described. Chemo-enzymatic resolution of racemic alcohols and amines were carried out with lipases using several substrates containing heteroatoms such as silicon, boron, selenium and tellurium. Biotransformation of nitriles by marine fungi, hydrolysis of epoxides by microorganisms of Brazilian origin and biooxidation of natural products were described. Enzymatic reactions under microwave irradiation, continuous flow, and enzymatic assays using fluorescent probes were reported.

1,1,3-Trichloro-2,4,5,6-tetrahydro-1H-1λ4-benzo[b]tellurophene (a = 8.807(1), b = 14.495(2), c = 9.263(1) Å, β = 110.18(1)°; P21/a, Z= 4, R[F 2 > 2σ(F 2)] = 0.0383), prepared by reacting 1-ethynyl-1-cyclohexanol with tellurium tetrachloride, displays a hexagonal grid structure made of four-membered Te2Cl2 and 12-membered Te6Cl6 rings formed by self-assembly of Cl-Te-Cl rods through Te···Cl secondary bonds into a supramolecular 2D network. The comparison with structurally related compounds reveals that 2D layers can also be formed by similar self-assembly of eight-membered Te4I4 rings alone or in a combination of four-membered Te2I2 with eight-membered Te4I4 rings.Key words: diorganotellurium(IV), supramolecular 2D assembly, self-assembly, secondary bonding.

1-(Phenylthio)-, 1-(phenylseleno)- and 1-(phenyltelluro)-propan-2-ol were efficiently resolved by CAL-B in sc-CO2.

The preparation and synthetic applications of selenium- and tellurium-stabilized carbanions as well as selenonium and telluronium ylides are reviewed. Selenium- and tellurium-stabilized carbanions are prepared by deprotonation or by element/lithium exchange of the parent selenides and tellurides. Additionally, selenium-stabilized carbanions are prepared by conjugate addition of organometallics to vinyl- and alkynyl selenides. Selenonium and telluronium ylides are prepared mainly by deprotonation of the parent selenonium and telluronium salts. The above-mentioned anionic species react with electrophiles, giving intermediates, which by subsequent transformations, lead to synthetically useful products. In the case of the selenium-stabilized carbanions, these sequences of reactions were applied in the synthesis of natural products. The tellurium counterparts were not yet explored for this purpose. Selenonium and telluronium ylides were not yet employed in total synthesis. Keywords: selenium-stabilized carbanions; tellurium-stabilized carbanions; selenium ylides; tellurium ylides; selenonium salts; telluronium salts; deprotonation; element/lithium exchange; reactivity and transformations; total synthesis

Several carbonyl functionalized Z-vinylic tellurides were synthesized. Infrared spectra of compounds 1 showed a peculiar pattern. Appreciable shifts to lower wavenumbers for both the VC─C and VC─O modes, as well as extensive mixing of such modes were observed. This behaviour could be rationalized in terms of a proposed Te-O interaction.