A New Preparation of Homochiral N-Protected 5-Hydroxy-3- piperidenes, Promising Chiral Building Blocks, by Palladium- Catalyzed Deracemization of Their Alkyl Carbonates

The palladium‐catalyzed deracemization of N‐protected alkyl carbonates of 5‐hydroxy‐3‐piperidenes by use of chiral phosphine ligands is described. A Trost ligand such as (R)‐BPA was found to be a suitable chiral ligand for the deracemization, providing N‐protected 5‐hydroxy‐3‐piperidenes in good yields with good to high enantioselectivities. A plausible mechanism for the reaction is proposed.