Switching of Sulfonylation Selectivity by Nature of Solvent and Temperature: The Reaction of beta-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.