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

Abstract

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.

Keywords

• sulfur(VI) fluoride exchange (SuFEx)
• asymmetric catalysis
• MacMillan catalyst
• soluble polymer catalyst
• recoverable organocatalyst