Direct organocatalytic asymmetric epoxidation of α,β-unsaturated aldehydes

The organocatalytic asymmetric epoxidation of α,β-unsaturated aldehydes with peroxides or sodium percarbonate is presented. Chiral pyrrolidine derivatives, proline and amino acid derived imidazolidinones mediate the asymmetric epoxidation of α,β-unsaturated aldehydes. For example, commercially available protected α,α-diphenyl-2-prolinol catalyzes the asymmetric formation of 2-epoxy-aldehydes in 81–95% conversion with up to 96:4 dr and 98% ee. The use of non-toxic catalysts, aqueous solvents and hydrogen peroxide or sodium percarbonate as the oxygen sources makes the reaction environmentally benign.