Fabrício Vargas

Synthesis of β-organotelluro vinylphosphine oxides by hydrotelluration of 1-alkynylphosphine oxides and their palladium-catalyzed cross-coupling with alkynes

Abstract β-Organotelluro vinylphosphine oxides 2 can be prepared by treatment of 1-alkynylphosphine oxides 1 with tellurolate anions in satisfactory yields. Compound 2d undergoes direct coupling reaction with terminal alkynes in the presence of PdCl 2 /CuI, triethylamine and methanol at room temperature to give β-alkynyl vinylphosphine oxides 3 with retention of configuration in good yields.

Sonogashira cross-coupling reaction of organotellurium dichlorides with terminal alkynes

The Sonogashira cross-coupling reaction of vinylic and heteroaromatic tellurium dichlorides has been explored, yielding the corresponding enynes and 2-alkynyl substituted heteroaromatic compounds. The reaction was carried out with PdCl2/CuI as catalysts and triethylamine as base, using methanol as solvent. The reaction proceeded under mild conditions and the cross-coupled products were obtained in good yields and in a stereoconservative manner.

Synthesis of new chiral imidazolidine disulfides derived from l-cystine and their application in the enantioselective addition of diethylzinc to aldehydes

Abstract Several chiral imidazolidine disulfides 4a–d derived from l -cystine have been synthesized. These ligands have been applied as chiral catalysts in the asymmetric addition of diethylzinc to aldehydes. The best results were obtained by employing 5 mol% of imidazolidine disulfide 4a , and chiral secondary alcohols were obtained in up to 91% e.e.

Catalytic enantioselective arylation of aldehydes: boronic acids as a suitable source of transferable aryl groups

The catalytic enantioselective arylation of several aldehydes using boronic acids as the source of transferable aryl groups is described; the reaction is found to proceed in excellent yields and high enantioselectivities (up to 97% ee) in the presence of a chiral amino alcohol.

An in vivo insight to the toxicological profile of various organotellurides.

In this study we have examined the in vivo toxic effects of various organochalcogens on hepatic, renal, glycemic and lipid profile. Diorganotellurium dichloride phosphonate (C1) at all tested doses did not modify serum alanine aminotransferase (ALT) activity in mice. While, 2-butyltellurium furan (C2) and dinaphthalene ditelluride (C3) at a dose of 0.75 and 0.125 mmol/kg caused an increase in aspartate aminotransferase (AST) and ALT activities. Our data showed that C1 caused an increase in urea content at different doses while treatment with C2 and C3 did not modify urea content. Treatment with C2 caused a significant alteration in serum glucose and fructosamine levels which explains the possible toxicity of these compounds. No significant changes were observed for cholesterol and triglycerides levels. These results suggest that organochalcogen compounds presented liver and renal toxicity and also altered glycemic profile which may leads to various clinical complications.