Chiral ketone-catalyzed asymmetric epoxidation of olefins with Oxone®

Chiral ketones 1 and 2 bearing 1-aza-7-oxabicyclo[3.5.0]decane skeleton and their C2-symmetric analogue 3 were readily prepared and evaluated as a chiral dioxirane precursor for asymmetric epoxidation of olefins with Oxone®. The ketone 2, bearing a diphenyl steric wall, was not effective and gave quite poor selectivity. Good selectivity up to 83% ee was obtained using 1 and 3, which suggested that Coulomb repulsion by carbonyl and ether oxygen atoms are operative as an electronic wall rather than a steric wall.