Purpurin-Promoted Photo-Redox Reduction of Benzyl Selenocyanates as Masked Selenols, Preparative, Electrochemical, Computational, and Mechanistic Study

BOUCHET, LYDIA M.; ARGÜELLO, JUAN E.; CASTRO-GODOY, WILLBER D.; SCHMIDT, LUCIANA C.; PUIATTI, MARCELO

ChemistrySelect

John Wiley and Sons Inc

Año: 2022 vol. 7 p. 1 - 10

The reduction of substituted benzyl selenocyanates to give the corresponding diselenides was performed by means of photo-redox catalysis using Eosin Y, Rhodamine 6G, Fluorescein, and Purpurin (PP) under LED irradiation. In all cases, diselenides were obtained as the only photoproducts; affording excellent yields when PP was used as photocatalyst under irradiation and air atmosphere in the presence of triethylamine (TEA). Our experimental findings indicate that despite TEA displays an acid-base equilibrium between PP and PP2−, only the former is photoactive. In addition, electrochemical properties of the selenocyanates under study were measured, finding that Se-CN moiety is relatively easy to reduce, around −1 V vs SCE. As a result, RC6H4CH2SeCN can act as masked selenols under photoinduced electron transfer conditions, making this methodology compatible with substituents (R) susceptible to hydrolysis or reduction. DFT calculations lead to a better insight into the reductive process.