A New Preparation of HomochiralN-Protected 5-Hydroxy-3- piperidenes, Promising Chiral Building Blocks, by Palladium- Catalyzed Deracemization of Their Alkyl Carbonates
The palladium-catalyzed deracemization of N-protected alkylcarbonates 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.