Substituent and Surfactant Effects on the Photochemical Reaction of Some Aryl Benzoates in Micellar Green Environment†

Effect of Confined and Micellar Media on the Photo-Fries Reaction of 4-Phenoxyphenol Esters: A Valuable Key Step Toward the Preparation of Aryloxyethyl Selenocyanates

The irradiation of a series of 4-phenoxyphenol esters in a sustainable micellar environment has been studied from both preparative and mechanistic viewpoints, and the results were compared with those obtained in cyclohexane solutions. These esters underwent the photo-Fries rearrangement reaction, and the microheterogeneous media induced a noticeable selectivity in favor of the ortho-regioisomer formation with yields up to 96% yield. UV-visible and 1D and 2D NMR (DCS, NOESY, and DOSY) spectroscopies have been employed to determine the binding constant (Kb) and the location of the esters within the hydrophobic core of the spherical micelles. Furthermore, the diffusion coefficient (D) and hydrodynamic radius (rs) were also measured. Application of the photo-Fries reaction of esters in microheterogeneous media as a key step in a multistep sequence has been carried out, leading to the preparation of (4-phenoxy)-(2-n-pentylcarbonyl)-phenoxyethyl selenocyanate (10), an interesting target molecule showing potential biological activity against Trypanosoma cruzi.

A density functional theory study on the mechanism of simultaneous trifluoromethylation and oximation of aryl-substituted ethylenes

The effects of different substituents, located at the para position of the aromatic ring and at the β-carbon atom of styrenes, on difunctionalizations involving trifluoromethylation and oxime formation are investigated, showing that the difunctionalization reaction has a good adaptability to such reactants containing a range of substituents. This is important in the actual production process. It was found that proton transfer in the final tautomerism step involving transformation of a nitroso intermediate into an oxime is the rate-limiting step. The solvent effect did not influence the rate-limiting step significantly. Compared with direct proton transfer in a vacuum, the energy barrier of the final tautomerism step decreased from 57.80 kcal mol−1 in vacuum to 12.98 kcal mol−1 in water occurring via mediated proton transfer, which declines by 77.5%. When water participates in the rate-limiting steps in organic solvents, the energy barrier also decreases significantly, which indicates that a small amount of water in the organic solvent is conducive to the reaction.

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

The photochemical reaction of sulfonate steroids in a sustainable environment was carried out successfully under steady-state conditions. Significant selectivity in photoproduct formation was also observed.

Induced selectivity in the photochemistry of estrone derivatives in sustainable and micellar environment: preparative and mechanistic studies

In this study, we carried out preparative and mechanistic studies on the photochemical reaction of a series of 3-acylestrone derivatives in confined and sustainable micellar environment under steady-state conditions and the results were compared with those obtained in cyclohexane solution. The aim of this work is mainly focused to show whether the nature of the surfactant (cationic, neutral and anionic) leads to noticeable selectivity in the photoproduct formation. The 3-acylestrone derivatives underwent the photo-Fries rearrangement, with concomitant homolytic fragmentation of the ester group and [1;3]-acyl migration. This pathway afforded the ortho-acyl estrone derivatives, the main photoproducts together with estrone. However, epimerization of the ortho regioisomer 2-acetylestrone and estrone through Norrish Type I photoreaction occurred involving the fragmentation of the C-α at the carbonyl group (C-17) of the steroid. UV-visible and 2D-NMR (NOESY) spectroscopies have been employed to measure the binding constant K_b and the location of the steroids within the hydrophobic core of the micelle.