Enantioselective synthesis of beta2-amino acids via Rh-catalyzed asymmetric hydrogenation with BoPhoz-type ligands: important influence of an N-H proton in the ligand on the enantioselectivity.
A series of BoPhoz-type ligands were successfully applied in the rhodium-catalyzed asymmetric hydrogenation of a number of beta-substituted or unsubstituted alpha-(phthalimidomethyl)acrylates, affording good to excellent enantioselectivities. The results suggested that the presence of an N-H proton in the BoPhoz backbone could significantly improve the enantioselectivity, and ligand (Sc,Rp)-1d, bearing two CF3-groups in the 3,5-position of the phenyl ring of aminophosphino moiety, showed the highest enantioselectivity.
Deng
Jun
J
Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
Hu
Xiang-Ping
XP
Huang
Jia-Di
JD
Yu
Sai-Bo
SB
Wang
Dao-Yong
DY
Duan
Zheng-Chao
ZC
Zheng
Zhuo
Z
D000596:Amino Acids / Q000138:chemical synthesis* / Q000737:chemistry; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D063065:Organophosphonates / Q000737:chemistry*; D012238:Rhodium / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization; D013237:Stereoisomerism
D000596:Amino Acids; D008024:Ligands; D063065:Organophosphonates; D012238:Rhodium