Asymmetric activation of the Pd catalyst bearing the tropos biphenylphosphine (BIPHEP) ligand with the chiral diaminobinaphthyl (DABN) activator.
[reaction: see text] The enantio- and diastereomerically pure Pd complex of the tropos biphenylphosphine (BIPHEP) ligand is obtained through complexation of the enantiopure (R)-diaminobinaphthyl (DABN) with either enantiomer of the BIPHEP-Pd catalyst, followed by tropo-inversion of the less favorable (S)-BIPHEP-Pd/(R)-DABN diastereomer to the more favorable (R)-BIPHEP-Pd/(R)-DABN diastereomer. The enantiopure BIPHEP-Pd catalyst with DABN affords higher enantioselectivity and catalytic efficiency as an activated Lewis acid catalyst than the enantiopure BIPHEP-Pd catalyst without DABN.
Mikami
Koichi
K
Department of Applied Chemistry, Tokyo Institute of Technology, Tokyo 152-8552, Japan. kmikami@o.cc.titech.ac.jp
Aikawa
Kohsuke
K
Yusa
Yukinori
Y