Asymmetric Mn(III)-based radical synthesis of functionalized 2,3-dihydrofurans

The oxidative radical addition of alkyl acetoacetates to p-methoxycinnamoyl oxazolidinones promoted by Mn(III) has been studied. It only gives trans-disubstituted 2,3-dihydrofurans, with d.r. ranging from 2:1 to 9:1, depending on the substituent of the chiral auxiliary. After chromatographic separation of the two diastereomers, the oxazolidinone can be removed to afford enantiopure dihydrofuranyl esters in good overall yield.