A Soluble Polymer-Bound Evans’ Chiral Auxiliary: Synthesis, Characterization and Use in Cycloaddition Reactions

The synthesis of novel soluble polymer-supported optically-active oxazolidinone (Evans(circle) chiral auxiliary) with different chiral monomer/styrene ratios is described. The polymer was obtained in high yields and then functionalized with trans-crotonic anhydride to give a high loading polymer (2.42 mmol/g). The reactivity was tested in the 1,3-dipolar cycloaddition with diphenylnitrone under catalyzed and uncatalyzed conditions. The cycloadducts could be obtained in high purities and fair yields after reductive cleavage. The stereoselectivity is parallel to that obtained with the model substrate under classical solution conditions.