New chiral oxazoline-phosphite ligands for the enantioselective copper-catalyzed 1,4-addition of organozinc reagents to enones

A series of new P,N-ligands with a binaphthyl and an oxazoline moiety were prepared, which are efficient ligands for the enantioselective copper-catalyzed 1,4-addition of organozinc reagents to enones. Increasing the steric bulk in the 3,3'-position of binaphthyl from an H to a biphenylyl moiety improved the ee from 65 to 94% in the reaction of diethylzinc with cyclopentenone. (C) 2000 Elsevier Science Ltd. All rights reserved.