Asymmetric cyclopropanation catalyzed by a series of copper-(Schiff-base) complexes with two chiral centers.
A series of copper(Schiff-base) complexes with two chiral centers derived from 1,2-diphenyl-2-amino-ethanol were synthesized and applied to catalyze the asymmetric cyclopropanation of ethenes with diazoacetates. A mechanism that can explain the observed results was proposed. Some of these complexes were also efficient catalysts for asymmetric cyclopropanation of 1,1-diphenylethene with ethyl diazoacetate, affording high e.e. of up to 98.6%. An e.e. of 80.7% was achieved when no solvent was used.
Jiang
Changsheng
C
Department of Chemistry, University of Science and Technology of China, Hefei 230026, People's Republic of China.
Ming
Zhang
Z
Tan
Qitao
Q
Qian
Dai
D
You
Tianpa
T