10.1021/jo050097d.s001
Da-Ming Du
Da-Ming
Du
Shao-Feng Lu
Shao-Feng
Lu
Tao Fang
Tao
Fang
Jiaxi Xu
Jiaxi
Xu
Asymmetric Henry Reaction Catalyzed by
<i>C</i><sub>2</sub>-Symmetric Tridentate Bis(oxazoline)
and Bis(thiazoline) Complexes:
Metal-Controlled Reversal of
Enantioselectivity
American Chemical Society
2005
Lewis acid center
C 2
Asymmetric Henry Reaction Catalyzed
tridentate chiral ligands
NH
Enantioselectivity C 2
Reversal
Bis
enantiomer
bi
Cu
Et 2 Zn complexes
2005-04-29 00:00:00
Journal contribution
https://acs.figshare.com/articles/journal_contribution/Asymmetric_Henry_Reaction_Catalyzed_by_i_C_i_sub_2_sub_Symmetric_Tridentate_Bis_oxazoline_and_Bis_thiazoline_Complexes_Metal_Controlled_Reversal_of_Enantioselectivity/3288769
<i>C</i><sub>2</sub>-symmetric tridentate bis(oxazoline) and bis(thiazoline)
ligands with a diphenylamine backbone have been investigated in the catalytic asymmetric Henry reaction of α-keto
esters with different Lewis acids. Their Cu(OTf)<sub>2</sub> complexes
furnished <i>S </i>enantiomers, while Et<sub>2</sub>Zn complexes afforded
<i>R </i>enantiomers, both of them with higher enantioselectivities
(up to 85% ee). Reversal of enantioselectivity in asymmetric
Henry reactions was achieved with the same chiral ligand
by changing the Lewis acid center from Cu(II) to Zn(II). The
results show that the NH group in <i>C</i><sub>2</sub>-symmetric tridentate
chiral ligands plays a very important role in controlling both
the yields and enantiofacial selectivity of the Henry products.