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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.

The inhibition of human cysteine cathepsins B, L, S and K was evaluated by a set of hypervalent tellurium compounds (telluranes) comprising both organic and inorganic derivatives. All telluranes studied showed a time- and concentration-dependent irreversible inhibition of the cathepsins, and their second-order inactivation rate constants were determined. The organic derivatives were potent inhibitors of the cathepsins and clear specificities were detected, which were parallel to their known substrate specificities. In all cases, the activity of the tellurane-inhibited cathepsins was recovered by treatment of the inactivated enzymes with reducing agents. The maximum stoichiometry of the reaction between cysteine residues and telluranes were also determined. The presented data indicate that it is possible to design organic compounds with a tellurium(IV) moiety as a novel warhead that covalently modifies the catalytic cysteine, and which also form strong interactions with subsites of cathepsins B, L, S and K, resulting in more specific inhibition.

Aims: To investigate the diversity and the catabolic capacity of oil-degrading Klebsiella strains isolated from hydrocarbon-contaminated sediments in San- tos-Sao Vicente estuary systems in Brazil. Methods and Results: Klebsiella strains obtained from the estuary were charac- terized using 16S rRNA gene sequencing and BOX-PCR patterns, testing their catabolic capacity to degrade toluene, xylene, naphthalene and nonane, and identifying the catabolic genes present in the oil-degrading strains. Results show that Klebsiella strains were widespread in the estuary. Twenty-one isolates from the Klebsiella genus were obtained; 14 had unique BOX patterns and were further investigated. Among four distinct catabolic genes tested (todC1, ndoB, xylE and alkB1), only the todC1 gene could be amplified in two Klebsiella strains. The biodegradation assay showed that most of the strains had the ability to degrade all of the tested hydrocarbons; however, the strains displayed different efficiencies. Conclusions: The oil-degrading Klebsiella isolates obtained from the estuary were closely related to Klebsiella pneumoniae and Klebsiella ornithinolytica. The isolates demonstrated a substantial degree of catabolic plasticity for hydrocar- bon degradation. Significance and Impact of the Study: The results of this study show that several strains from the Klebsiella genus are able to degrade diverse hydrocar- bon compounds. These findings indicate that Klebsiella spp. can be an impor- tant part of the oil-degrading microbial community in estuarine areas exposed to sewage.

The easily obtained β-phenylseleno α,β-unsaturated aldehydes react with Grignard reagents and with n-butyllithium leading to the 1,2-addition products, which upon acidic hydrolysis in the presence of silica gel afford the selenium-free α,β-unsaturated carbonyl compounds with 1,3-carbonyl transposition.

The primary geometry about the Te IV atom in the title compound, C 12 H 13 Cl 3 OTe or [TeCl 2 (C 9 H 8 Cl)(C 3 H 5 O)], is a pseudo-trigonal-bipyramidal arrangement with the lone pair of electrons and the C atoms occupying the equatorial positions, and the Cl atoms occupying the axial positions. There are three secondary interactions, two intramolecular [Te…O 2.926(4) and Te…Cl 3.180(1) A] and one intermolecular [Te…Cl 3.659(1) A], which link the molecules. Significant distances and angles are: Te-Cl 2.4870(13) and 2.5096(12), Te-C 2.119(4) and 2.122(4) A, Cl-Te-Cl 171.78(5), Cl-Te-C 88.07(11), 87.68(15), 86.28(11) and 87.17(15), and C-Te-C 97.59(17)°.

Through direct transmetalation reaction of Z-vinylic tellurides with nBuLi was observed the unexpected isomerization of double bonds leading to potassium E-vinyltrifluoroborates salts in low to moderate yields. Using EPR spin trapping experiments the radical species that promoted the stereoinversion of Z-vinylic organometallic species during the preparation of potassium vinyltrifluoroborate salts was identified. The experiments support the proposed mechanism, which is based on the homolytic cleavage of the TenBu bond.

Vinylic tellurides react with higher order dialkylcyanocuprates leading to mixed vinylcyanocuprates with retention of the olefin geometry. The mixed vinylcyanocuprates react with enones giving the 1,4-addition products in good yields.

Dihalocarbenes generated under phase transfer conditions add to cis and trans vinylic selenides to give the corresponding 1,1-dihalo-2-selenocyciopropanes with retention of configuration.

( Z )-β-Butyltellanyl α,β-unsaturated carbonyl compounds were stereoselectively produced by hydrotelluration of alkynones or by an addition/elimination sequence from enol tosylates. The β-butyltellanyl-enones were chemoselectively reduced with NaBH 4 /MeOH, NaBH 4 ·CeCl 3 ·7H 2 O/MeOH and DIBAL-H systems to the corresponding allylic alcohols with retention of the Z stereochemistry.

Organotellurium trichlorides are efficiently reduced with sodium borohydride. The intermediate organo tellurolates are transformed into diaryl ditellurides, alkyl aryl tellurides, tellurides containing a cyclic ether, and vinylic tellurides.

tert -Butyldimethylsilyl ethers of propargylic alcohols are hydrotellurated regioselectively to give 1,2- Z -vinylic tellurides. Enantiomerically pure propargylic alcohols give enantiomerically pure vinylic tellurides, which are coupled with alkynes under Pd catalysis to give enantiomerically pure allylic enynols.

Volatile compound biodegradation analysis usually requires the time-consuming step of extraction of the analytes from the matrix using organic solvents or costly radioactive-compounds. Thus, it is desirable to have a simple and fast technique to generate a good evaluation of bacterial biodegradation. The goal of this research was to develop a methodology on the basis of static headspace-gas chromatography/mass spectrometry (HS-GC/MS) to evaluate the level of volatile contaminant biodegradation. The effects of the following parameters were studied: temperature and time of equilibration. The biodegradation experiments were carried out with bacteria inoculation in mineral media in presence of volatile hydrocarbon compounds (toluene, p-xylene, nonane and naphthalene). Autoclaved inoculates were used as control and reference sample. The optimal headspace conditions were observed when the vials were heated at 80 degrees C for 20 min, the syringe at 81 degrees C and an injection volume of 0.4 mL was used. This methodology has the advantage of being relative free from matrix effects.

New organotellurium(IV) compounds with specific cysteine protease inhibitory activity were synthesized. Serine and aspartic protease activity were not affected by any of these compounds. All Te(IV) compounds tested exhibited high specific second-order constant for cathepsin B inactivation. Tellurium(IV) compound 6 was the best inhibitor of the series, showing a second-order constant of 36,000 M(-1)s(-1). This value is about 100-fold higher than the second-order rate for cysteine protease inactivation shown by the historic Te(IV) compound AS 101 (1). The inhibition was irreversible and time and concentration dependent; no saturation kinetics were observed, suggesting a direct bimolecular reaction. The results described in this paper show that the new organotellurium(IV) compounds are powerful inhibitors of cathepsin B, constituting promising potential anti-metastatic agents.

In the title compound, [TeCl 2 (C 8 H 6 Cl)(C 7 H 7 O)], the Te IV atom is in a trigonal bipyramidal configuration with the lone pair of electrons occupying one of the equatorial positions. Distances and angles are: Te-Cl 2.521 (2) and 2.485 (2), Te-C 2.073 (7) and 2. 110 (7) A (aryl); Cl-Te-Cl 117.65 (8), Cl-Te-C 87.1 (2), 90.6 (2), 90.8 (2) and 90.6 (2), C-Te-C 95.0 (3)°

The geometry around the Te atom in the anion in C13H22N+·C3H3Cl4OTe− is distorted pseudo-octahedral with three Cl atoms and the O atom forming the equatorial plane, and the C atom lying opposite the tellurium lone pair. Distances and angles are: Te—O 2.0120 (18), Te—C 2.072 (2), Te—Cl 2.5239 (7), 2.5283 (7) and 2.5577 (7) A; O—Te—C 81.61 (9), O—Te—Cl 90.69 (6), 90.99 (6) and 168.13 (5), C—Te—Cl 87.13 (8), 86.64 (8) and 86.59 (8), and Cl—Te—Cl 87.02 (2), 90.00 (3) and 173.24 (3)°. The anions are arranged in an infinite zigzag chain parallel to the a axis through a secondary Te⋯Cl bond [3.8391 (8) A].

[TeCl 2 (C 9 H 8 Cl)(C 7 H 7 O)] cristallise dans Pbcn avec a=18,829, b=8,809, c=20,969 A, Z=8; affinement jusqu'a R=0,034. L'ion Te(IV) adopte une configuration bipyramide rhomboedrique avec une paire libre d'electrons en position equatoriale

A homoenolate generated by tellurium/lithium exchange reaction was employed in a straightforward enantioselective synthesis of (+)-endo-brevicomin in 70% yield and 84.4% e.e. Um homoenolato gerado pela reação de troca telúrio/lítio foi aplicado na síntese enantioseletiva do (+)-endo-brevicomin com 70% de rendimento isolado e 84,4% de e.e.

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.

The primary geometry about the Te(IV) atom in the title compound, [TeCl2(C8H6Cl)(C3H5O)] or C11H11Cl3OTe, is a pseudo-trigonal-bipyramidal arrangement, with two Cl atoms in apical positions, and the lone pair of electrons and C atoms in the equatorial plane. The Te(IV) atom is involved in three secondary interactions, two intramolecular [Te...O = 2.842 (3) A and Te.Cl3 = 3.209 (1) A] and one intermolecular [Te...Cl = 3.637 (1) A], the latter giving rise to a helical chain. These helices are linked by C-H...O interchain interactions.

Dihalocarbenes generated under phase transfer conditions add to cis and trans vinylic selenides to give the corresponding 1,1-dihalo-2-selenocyciopropanes with retention of configuration.

In this paper we describe a systematic preparation and oxidation of several aryl benzyl tellurides.

Pyrolysis of α-acyl,α-thio phosphoranes affords thioacetylenes in good yield. The thio acetylenes are precursors of terminal and alkyl disubstituted acetylenes.

Selenophosphonates of the general formula (EtO)2P(O)CHRSePh were prepared and their reactions with aldehydes and ketones investigated. The products formed are vinylic selenides having predominantly the E configuration. Hydrolytic cleavage of these products gives the corresponding ketones.

[TeCl 2 (CHOC 6 H 4 )(C 8 H 11 O 2 )]•0,27CHCl 3 cristallise dans le systeme hexagonal, groupe d'espace P6 5 et sa structure est affinee jusqu'a R=0,0471. Coordination pseudo bipyramidale rhomboedrique autour de Te

A procedure is described which allows for the in situ synthesis of arylalkyl, diaryl and dialkylchalcogenides under phase transfer conditions starting from the corresponding diorganodichalcognides. The dichalcogenides are reduced by aminoiminomethanesulfinic acid (thiourea dioxide) in alkaline medium and catalyzed by a quaternary ammonium salt. The reduction proceeds easily for diaryl disulfides and diaryl diselenides at a sodium hydroxide concentration of 13%; diaryl ditellurides require a 50% sodium hydroxide solution to give the aryl tellurolate anion. The dialkyl diselenides and dialkyl ditellurides are more difficult to reduce. The intermediate arylthiolates and arylselenolates are quenched by alkyl and activated aryl halides to give the corresponding sulfides and selenides in high yield (77–97%). The aryltellurolates react with alkyl halides giving the aryl alkyl tellurides in 81–96% yield. The procedure could not be successfully used for the synthesis of dialkylselenides and dialkyl tellurides; low yields and mixture of products were formed.

Acetylenic selenides and tellurides were prepared in good yields by nucleophilic substitution at acetylenic carbon by reaction of selenolate and tellurolate anions with 1-bromo, 2-phenyl ethyne.

Synthese par lithiation d'hydrocarbures halogenes de tellurure de phenylethynyl et d'alkyl. Ces composes conduisent a des ditellurures symetriques et des tellurures vinyliques non symetriques

Elemental tellurium is reduced by thioureadioxide in alkaline medium, leading to disodium telluride or ditelluride, depending on the amount of thioureadioxide used. The intermediate disodium telluride or ditelluride reacts “in situ” with alkyl halides to give dialkyltellurides or dialkylditellurides in high yield.

The addition of selenophenol to mono - and di-substituted unactivated acetylenes have been investigated. At room temperature the vinylic selenides obtained were predominantly of the Z configuration; at 120°C Z/E mixtures were produced. Vinylic selenides with the E configuration were obtained by reduction of the corresponding selenoacetylenes with lithium aluminium hydride.

Butyl vinyl tellurides and bis-vinyl tellurides furnish vinyllithiums with retention of configuration in good yields upon treatment with n-butyllithium at −78°C.

The transylidation reactions of PhSeBr with two equivalents of an alkylidene-triphenylphosphorane give selenophosphoranes, Ph3P=CRSePh. These also can be obtained by treating the corresponding selenophosphonium salts, prepared by quarternization of triphenylphosphine with PhSeCHRBr, with n-BuLi. The selenophosphoranes react with aldehydes in situ (Wittig reaction) to give the expected vinylic selenides in good yields. The stereochemistry of the reactions is discussed.

Aryltellurium trihalides, arylselenium trihalides, organyltellurium and selenium dichlorides and organylselenoxides and telluroxides were reduced in high yield to the corresponding diaryl ditellurides and selenides with thiourea dioxide in a two phase system.

β,β-Bis-(phenylseleno) carbonyl compounds were prepared by reacting the corresponding silyl enol ether with tris-(phenylseleno) methane in the presence of tin tetrachloride.