Organocatalytic Epoxidation Using Hypervalent Iodine Reagents

Significance

Here the authors report an enantio­selective organocatalytic epoxidation of α,β-unsaturated aldehydes using hypervalent iodine reagents. Catalyst 1 in combination with TfOH or HClO₄ has been found to be effective for this reaction. Iodosobenzene (PhI=O) (eq. 1) or [(nosylimino)iodo]benzene (NsNIPh) (eq. 2) have been used as the source of oxygen. With 20 mol% of catalyst 1, moderate to high yields and enantioselectivities are obtained for different alkyl- or aryl-substituted α,β-unsaturated aldehydes.