Direct construction of chiral quaternary dihydropyranones through highly enantioselective organocatalytic hetero-Diels–Alder reactions of olefinic azlactones

Abstract

The first organocatalytic hetero-Diels–Alder reaction of an in situ generated diene with either α-keto esters or β,γ-unsaturated α-keto esters was successfully developed. The densely functionalized dihydropyranones with a highly congested quaternary center were readily obtained in moderate to good yields with excellent enantioselectivities under mild conditions.