Readily available chiral phosphine-aminophosphine ligands for highly efficient Rh-catalyzed asymmetric hydrogenation of alpha-enol ester phosphonates and alpha-enamido phosphonates.
A new class of unsymmetrical hybrid phosphine--aminophosphine ligands has been prepared from commercially available, inexpensive (S)-1-phenylethylamine through a concise synthetic procedure. These ligands are not very sensitive to air and moisture, and displayed good enantioselectivities in the Rh-catalyzed asymmetric hydrogenation of various dimethyl alpha-benzoyloxyethenephosphonates bearing beta-aryl, beta-alkyl, and beta-alkoxy substituents and N-benzyloxycarbonyl alpha-enamido phosphonates, in which up to 97% ee was obtained. A side-by-side comparison study disclosed that these new phosphine--aminophosphine ligands showed better enantioselectivity than BoPhoz ligands.
Wang
Dao-Yong
DY
Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
Huang
Jia-Di
JD
Hu
Xiang-Ping
XP
Deng
Jun
J
Yu
Sai-Bo
SB
Duan
Zheng-Chao
ZC
Zheng
Zhuo
Z