A highly efficient one-pot construction of optically active
1,1â²-spirobi[indan-3,3â²-dione] derivative (up to 80% ee) has
been achieved by exploiting the double intramolecular CâH insertion
reaction of dimethyl
2,2â²-methylenebis(α-diazo-β-oxobenzenepropanoate) under
the influence of dirhodium (II)
tetrakis[N-phthaloyl-(R or
S)-tert-leucinate] as a catalyst.
Asymmetric Henry Reaction Catalyzed by <i>C</i><sub>2</sub>-Symmetric Tridentate Bis(oxazoline) and Bis(thiazoline) Complexes: Metal-Controlled Reversal of Enantioselectivity
作者:Da-Ming Du、Shao-Feng Lu、Tao Fang、Jiaxi Xu
DOI:10.1021/jo050097d
日期:2005.4.1
C2-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 Lewisacids. Their Cu(OTf)2 complexes furnished S enantiomers, while Et2Zn complexes afforded R enantiomers, both of them with higher enantioselectivities (up to 85% ee). Reversal of enantioselectivity in asymmetric