Product selectivity of the photoreaction of aryl sulfonates and mesylate of estrone derivatives in sustainable and micellar media. A steady-state investigation.

QUINDT, MATIAS; GOLA, GABRIEL F.; RODRIGUEZ, CRISTIAN; RAMIREZ, JAVIER; BONESI SERGIO M.

NEW JOURNAL OF CHEMISTRY

ROYAL SOC CHEMISTRY

Lugar: CAMBRIDGE; Año: 2022 vol. 46 p. 15504 - 15520

1144-0546

Abstract. Preparative and mechanistic studies on the photochemical reaction of a series of aryl sulfonates and mesylate of estrone and 17-norestrone derivatives in confined and sustainable micellar environment under steady-state conditions were carried out successfully and this photochemical behavior was checked against methanol solution. The goal of this work resides in the fact that a noticeable selectivity in favor of the formation of ortho-regioisomers as the main photoproducts over the formation of estrone (or 17-norestrone) was brought about the nature of the surfactant, i.e. cationic, anionic and neutral. Certainly, the micelles provide the confinement of the sulfonic esters within the hydrophobic core inhibiting the diffusion of the photogenerated radical species into the bulk solution. Because the photoreaction was studied in micellar solutions, the measurement of the binding constant Kb and estimation of the location of the steroids within the hydrophobic core of the micelle have been achieved successfully employing UV-visible, 1D-NMR and 2D-NMR spectroscopies. The binding constant values and Differential Chemical Shift (DCS) analysis showcased the solubilization of the sulfonates within the hydrophobic core. Additionally, Nuclear Overhauser Effect Spectroscopy (NOESY) experiments clearly demonstrated the location of the sulfonates within the micelle and likewise, Diffusional Ordered Spectroscopy (DOSY) experiments definitively showed that steroids and micelle behave like a unique supramolecular entity.