Síntese de calcogenocromonas utilizando Oxone® e luz visível

Abstract

The present work describes the results obtained for the synthesis of 3-organoselanylthiochromones and 3-organoselanylchromones through the radical cyclization reaction of ortho-thioarylinones or ortho-methoxyarylinones and diorganoyl diselenides promoted by Oxone®. Through the developed method, it was possible to perform the construction and selenofunctionalization of thiochromones and chromones using Oxone® as a stable and non-hazardous oxidizing agent in the presence of CH3CN at 82 °C. The reactions tolerate a variety of substituents and have enabled the synthesis of twenty-one new 3-organoselanylthiochromones and 3-organoselanylselanylchromones in good to excellent yields (55-95%). Furthermore, the developed method proved to be suitable for scale-up (3.0 mmol, 80%) and the synthetic utility of the prepared compounds was demonstrated in the oxidation of 2-phenyl-3-(phenylselanyl)-4H-thiochromen-4-one which can be applied in selenoxide elimination reactions. In addition, a visible light-mediated method was developed to obtain 3-sulfenylthiochromones via the radical cyclization reaction of ortho-thioarylinones and thiols. The reaction is triggered by the formation of a sulfur-centered radical, which is formed by light excitation of an intramolecular electron donor-acceptor complex (EDA-complex). A total of twenty-one compounds were prepared (sixteen novel), with yields ranging from 28 to 98%. The reactions were conducted under open atmosphere, requiring no metal catalysts, oxidizing species or heating, making this an environmentally friendly methodology to access valuable compounds.