SuFEx-Click Approach for the Synthesis of Soluble Polymer-Bound MacMillan Catalysts for the Asymmetric Diels–Alder Reaction

Novel polymeric MacMillan catalysts were prepared from modified chiral imidazolidin-4-one monomers via sulfur(VI) fluoride exchange chemistry. The resulting polysulfates containing chiral imidazolidin-4-one units could be employed as polymeric organocatalysts for the asymmetric Diels–Alder reaction. With the use of these polysulfate catalysts, sufficient catalytic activity and enantioselectivity were obtained, which were similar to those obtained by monomeric catalysts in a homogeneous catalytic reaction. In addition, the polysulfate catalysts could be recovered and reused five times without a considerable loss of activity and selectivity.

PEG-Supported Hypervalent Iodine Reagent for Sulfonamide Synthesis

A reusable and recoverable PEG-supported hypervalent iodine reagent is reported. This hypervalent iodine reagent, immobilized in a soluble polymer support, was easily prepared in six steps from PEG-OH 2000. This reagent was successfully applied in a mild sulfonamide synthesis using a sulfinate salt and an amine in up to 95% yield. The use of the soluble polymer allowed a facile workup procedure and reaction monitoring, by simple precipitation and filtration of the reagent, with an easy recovery and subsequent re-oxidation and reuse. This approach greatly improves the sustainability of this sulfonamide synthesis method, avoiding frequent preparation of reagents and generation of waste during the purification steps.