Switching of Sulfonylation Selectivity by Nature of Solvent and Temperature: The Reaction of β-Dicarbonyl Compounds with Sodium Sulfinates under the Action of Iron-Based Oxidants
Selectivity of sulfonylation of β-keto esters with sodium sulfinates under the action of iron(III) salts as oxidants can be regulated by the type of solvent used and the reaction temperature. α-Sulfonyl β-keto esters are obtained when the process is conducted in THF/H2O solution at 40 °C. The change of the solvent to iPrOH/H2O and refluxing of a reaction mixture provides α-sulfonyl esters – the products of successive sulfonylation-deacylation. When β-diketones are applied as starting materials, only α-sulfonyl ketones are formed. The reaction pathway includes sulfonylation of dicabonyl compounds under the action of Fe(III) to form α-sulfonylated dicarbonyl compounds, which are then attacked by a solvent as the nucleophile, resulting in the products of successive sulfonylation-deacylation. Participation of the solvent in the reaction pathway determines the products structure.
Mulina, Olga M.,Pirgach, Dmitry A.,Nikishin, Gennady I.,Terent'ev, Alexander O.
p. 4179 - 4188
(2019/05/08)
Iodine-catalysed sp3 C-H sulfonylation to form β-dicarbonyl sulfones with sodium sulfinates
An efficient and easily handled method for β-dicarbonyl sulfones with sodium sulfinates as the sulfonyl source was developed. This transformation was involved in the iodine-catalysed sp3 C-H sulfonylation of β-dicarbonyl compounds. This journal
Metal-free desulfonylation reaction through visible-light photoredox catalysis
The desulfonylation of β-arylketosulfones has been achieved in good to excellent yields by using 3-W blue LEDs light, 1 mol-% organic dye eosin Y bis(tetrabutylammonium salt) as photocatalyst, and diisopropylethylamine as reducing agent. Mechanistic studies demonstrate that oxidative quenching of the excited eosin Y by β-arylketosulfones plays a crucial role in the present photoredox catalytic cycle. Reductive desulfonylation is essential to enable to use of a sulfone as an auxiliary group. For reductive removal of sulfones, highly aggressive metal-containing reducing agents and harsh reaction conditions are often employed. In this paper, metal-free desulfonylation of β-arylketosulfones can be achieved efficiently at room temperature under visible-light irradiation.