Palladium-Catalyzed Enantioselective Cycloaddition of Carbonylogous 1,4-Dipoles: Efficient Access to Chiral Cyclohexanones

A novel
palladium-mediated carbonylogous 1,4-dipole was developed
by in situ deprotonation. By using our own-developed C2-unsymmetric phosphoramidite as supporting ligand, this
dipole was applied to the asymmetric synthesis of chiral cyclohexanones
via a catalytic [4+2] cycloaddition.
Electron-deficient allylic carbonate was used to generate the highly
reactive palladium-mediated dipoles for the first time, and a diverse
array of stable dipole precursors was explored for the elaboration
of chiral cyclohexanones. A general mechanism for the reaction process
and stereochemical outcome was proposed, which can be useful in designing
and predicting future transformation.