Oscar E. D. Rodrigues

An efficient one-pot synthesis of symmetrical diselenides or ditellurides from halides with CuO nanopowder/Se0 or Te0/base.

A CuO nanopowder-catalyzed coupling reaction of aryl, alkyl, and heteroaryl iodides with elemental selenium and tellurium takes place in the presence of KOH at 90 degrees C in DMSO. A wide range of substituted symmetrical diselenides and ditellurides were afforded with good to excellent yields.

Eco-friendly cross-coupling of diaryl diselenides with aryl and alkyl bromides catalyzed by CuO nanopowder in ionic liquid

An eco-friendly cross-coupling reaction of aryl and alkyl bromides with diselenides using a catalytic amount of CuO nanopowder as a catalyst and an ionic liquid as a recyclable solvent is reported. The system shows high efficiency to catalyze this transformation, and in a green fashion due to the recyclable approach and the non-residual design protocol. This procedure has been utilized for the synthesis of a variety of diaryl selenides in good to excellent yields from the readily available aryl and alkyl bromides and diselenides.

C–S cross-coupling of thiols with aryl iodides under ligand-free conditions using nano copper oxide as a recyclable catalyst in ionic liquid

A recyclable copper nanopowder catalyst in ionic liquid is effective for promotion of the cross-coupling reaction of various thiols with aryl iodides under ligand-free conditions. Compared to the usual organic solvents, [bmmim]BF4 exhibited higher performance with the advantage of being able to be reused for up to four successive runs.

Efficient synthesis of selenoesters from acyl chlorides mediated by CuO nanopowder in ionic liquid

Herein, we report an eco-friendly synthesis of selenoesters from acyl chlorides catalyzed by recyclable CuO nanopowder in ionic liquid as a recyclable solvent in good to excellent yields. This protocol shows high efficiency in catalyzing this transformation in a greener fashion than previous protocols due to the non-residual methodological design.

Synthesis of chalcogenol esters from chalcogenoacetylenes

Abstract Thiol and selenol esters were conveniently prepared in good yields by reacting chalcogenoacetylenes with trifluoroacetic acid in dichloromethane in the presence of silica.

New organochalcogen multitarget drug: synthesis and antioxidant and antitumoral activities of chalcogenozidovudine derivatives.

In this article we present the synthesis, characterization, and in vitro biological and biochemical activities of new chalcogenozidovudine derivatives as antioxidant (inhibition of TBARS in brain membranes and thiol peroxidase-like activity) as well as antitumoral agents in bladder carcinoma 5637. A prominent response was obtained for the selected chalcogenonucleosides, showing effective antioxidant and antitumoral activities.

Synthesis of Diorganyl Selenides Mediated by Zinc in Ionic Liquid

A new approach for the synthesis of diorganyl selenides is described. By using economically attractive zinc dust in BMIM-BF(4), a series of diorganyl selenides were efficiently achieved in excellent yields, under neutral reaction conditions. Compared to the usual organic solvents, BMIM-BF(4) exhibited higher performance with the advantage to be reused up to five successive runs.

New C2-symmetric chiral disulfide ligands derived from (R)-cysteine

Abstract Several sulfur-containing optically active C 2 -symmetrical ligands have been synthesized from ( R )-cysteine and applied successfully as chiral catalysts in the asymmetric addition of diethylzinc to aldehydes. The resulting secondary alcohols could be obtained in good yields and excellent enantiomeric excess.

Selenides and diselenides containing oxadiazoles: a new class of functionalised materials

A simple and efficient procedure for the synthesis of a new class of organoselenium liquid crystal compounds was developed. The coupling of aryl bromides with elemental selenium was catalysed using copper oxide nanopowder in the presence of potassium hydroxide employing dimethyl sulfoxide as the solvent. This is the first report of the synthesis and characterisation of liquid crystal-based diselenides. Their mesophases were characterised by polarising optical microscopy and differential scanning calorimetry. Compounds 1, 2 and 4b exhibited the smectic A phase. In addition, these compounds showed weak blue fluorescence in solution (λmax. em. 350–405 nm) and a Stokes shift of around 90 nm.

Studies on the antioxidant effect and interaction of diphenyl diselenide and dicholesteroyl diselenide with hepatic δ-aminolevulinic acid dehydratase and isoforms of lactate dehydrogenase

Studies on the interaction of dicholesteroyl diselenide (DCDS) and diphenyl diselenide (DPDS) with hepatic delta-aminolevulinic acid dehydratase (ALA-D) and different isoforms of lactate dehydrogenase (LDH) from different tissues were investigated. In addition, their antioxidant effects were tested in vitro by measuring the ability of the compounds to inhibit the formation of hepatic thiobarbituric acid reactive species (TBARS) induced by both iron (II) and sodium nitroprusside (SNP). The results show that while DPDS markedly inhibited the formation of TBARS induced by both iron (II) and SNP, DCDS did not. Also, the activities of hepatic delta-aminolevulinic acid dehydratase (ALA-D) and different isoforms of lactate dehydrogenase (LDH) were significantly inhibited by both DPDS and DCDS. Moreover, we further observed that the in vitro inhibition of different isoforms of lactate dehydrogenase by DCDS and DPDS likely involves the modification of the groups at the NAD+ binding site of the enzyme. Since organoselenides interacts with thiol groups on proteins, we conclude that the inhibition of different isoforms of lactate dehydrogenase by DPDS and DCDS possibly involves the modification of the thiol groups at the NAD+ binding site of the enzyme.