Organocatalytic Asymmetric Peroxidation of γ,δ-Unsaturated β-Keto Esters-A Novel Route to Chiral Cycloperoxides.

A methodology for the asymmetric peroxidation of γ,δ-unsaturated β-keto esters is presented. Using a cinchona-derived organocatalyst, the target δ-peroxy-β-keto esters were obtained in high enantiomeric ratios of up to 95:5. Additionally, these δ-peroxy esters can be readily reduced to chiral δ-hydroxy-β-keto esters without impacting the β-keto ester functionality. Importantly, this chemistry opens up a concise route to chiral 1,2-dioxolanes, a common motif in many bioactive natural products, via a novel P 2 O 5 -mediated cyclisation of the corresponding δ-peroxy-β-hydroxy esters.