Asymmetric 1,4-disubstitution of 1,3-dienes: Palladium(II)-catalyzed formation of azido-ketones from 1,3-cyclohexadiene

The oxidation of cyclohexadiene in a mixed aqueous solvent in the present of azide ion produced 4-azido-2-cyclohexene-1-one, 1, and 2-azido-3-cyclohexene-1-one, 2, in a four electron transfer in about a 70% yield. The overall reaction is a net air oxidation. These enantioselectivies are higher than any obtained previously for addition to 1,3-dienes. The conversion of 1 to 2 involves a [3,3]sigmatropic rearrangement.