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 beta-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. alpha-Sulfonyl beta-keto esters are obtained when the process is conducted in THF/H2O solution at 40 degrees C. The change of the solvent to iPrOH/H2O and refluxing of a reaction mixture provides alpha-sulfonyl esters - the products of successive sulfonylation-deacylation. When beta-diketones are applied as starting materials, only alpha-sulfonyl ketones are formed. The reaction pathway includes sulfonylation of dicabonyl compounds under the action of Fe(III) to form alpha-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.