Lipase-Palladium Co-Catalyzed Dynamic Kinetic Resolution of Racemic Allylic Esters.

Dynamic kinetic resolution (DKR) by combining lipase-catalyzed esterification of racemic sec-alcohols and in situ racemization has been widely studied; however, reports on DKR involving lipase-catalyzed hydrolysis of racemic esters are scarce. This problem is probably due to the lack of more effective and general racemization methods. Herein, we report the enhanced hydrolytic DKR of racemic allylic esters. The discovery of the monodentate ligand P[C6H3-2,6-(OMe)2]3, which in situ generates Pd complex(es) highly reactive to racemization and the NaOAc-mediated acceleration of racemization, are notable breakthroughs. Consequently, the DKR of racemic allylic esters can be completed in a few hours at 40 °C in most cases, yielding optically active allylic alcohols (93 % ee to >99 % ee) in 58-91 % isolated yields with minimal side reactions.