We present here our results on the temperature controlled, selective hydrochalcogenation of 1,4-diorganyl-1,3-butadiynes with nucleophilic species of selenium, tellurium and sulfur generated in situ from the respective diaryl dichalcogenide and NaBH4. Using polyethylene glycol (PEG)-400 at 30 ºC the (Z)-chalcogenoenynes are obtained and at 90 ºC the (Z,Z)-bis-chalcogen-1,3-butadienes are produced in good to excellent yields. Alternatively to conventional oil bath heating, the use of microwave irradiation is also presented as an alternative energy source that provides the expected products in few minutes.

We present here our results in the synthesis of eleven new 3-(1H-1,2,3-triazol-1-yl)-2-(arylselanyl)pyridines by copper-catalyzed azide-alkyne cycloaddition reactions. The reactions were performed in the presence of catalytic amount of copper(II) acetate and sodium ascorbate using a mixture of tetrahydrofuran/water (1:1) as solvent at room temperature in air. The reaction is tolerant to different functional groups such as substituted-benzene rings, alcohol and ester and none electronic or steric influence was observed. All the products were obtained in good to excellent yields. Alternatively to the conventional oil bath heating, the use of microwave irradiation or ultrasound methods is also presented as alternative energy sources.

Este trabalho descreve nossos resultados para a reação entre benzenosselenol, gerado in situ pela reação entre disseleneto de difenila com H3PO2, com uma série de (E)-chalconas utilizando glicerol como solvente. Utilizando as condições de reação otimizadas, uma variedade de produtos de redução 1,4-quimiosseletivas podem ser obtidos em bons rendimentos. A mistura glicerol/H3PO2 pode ser facilmente recuperada e reutilizada em condições de reação de redução 1,4-quimiosseletivas por ciclos sucessivos sem perda de eficiência. Adicionalmente, sob condições de reação de redução 1,4-quimiosseletivas, o produto natural zingerona pode ser sintetizada em bom rendimento.

We describe herein our results for the reaction of benzeneselenol, generated in situ by reaction of diphenyl diselenide with H3PO2, with various (E)-chalcones using glycerol as solvent. Using our optimized reaction conditions, a range of chemoselective 1,4-reduction products could be obtained in good yields. The glycerol/H3PO2 system can be easily recovered and reused in chemoselective 1,4-reductions for successive cycles without loss of efficiency. Additionally, under 1,4-reducing reaction conditions, the natural product zingerone can be synthesized in good yield.