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Benzeneseleninic Acid in the Photo-Catalyzed beta-Hydroxyselenylation of Styrenes
* , , , *
1  Federal University of Pelotas

Abstract:

We established a new synthetic methodology for the regioselective β-hydroxyselenilation of olefins employing benzeneseleninic acid and promoted by blue LED light, as alternative energy source. Using a novel perspective, the bezeneseleninic acid emerges as an efficient and affordable reagent to be used as electrophilic selenium source, since in the presence of visible light it is easily converted to a radical species. In this sense, the photocatalytically formed PhSeradical can react directly with unsaturated substrates affording a radical selenium-containing intermediate. Following, it can react with radical HO, generated from different reaction steps, that are present in the reaction medium, leading to the formation of the desired β-hydroxyselanyl compounds. This class of molecules have demonstrated important biological activities and versatile utilities in organic synthesis, as building blocks. For this reason, it is interesting to develop robust, effective, and environmentally benign methodologies for their preparation. The optimal reaction conditions involves the use of styrene as unsaturated substrate and 1.0 equiv. of phenylseleninic acid, as organoselenium source, in the presence of 5.0 mol% of eosin Y, an organic photocatalyst, in 1.5 mL of DMSO. The system was stirred and irradiated with blue LED light for 2 hours, resulting in an efficient and smoothly way for access β-hydroxyselanyl compounds in good yields.

Keywords: benzeleseleninic acid; beta-hydroxyselenation; visible-light; green chemistry
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