Design of Chiral Phase Transfer Catalyst with Conformationally Fixed Biphenyl Core: Application to Asymmetric Alkylation of Glycine Derivatives
作者:Yong-Gang Wang、Keiji Maruoka
DOI:10.1021/op0602324
日期:2007.5.1
Chiral phase transfer catalysts (S)-1a and (S)-1b with a conformationally fixed biphenyl core were conveniently prepared from the known (S)- 6,6')-dimethylbiphenyl- 2,2')- diol 2 in five steps. These catalysts, (S)-1a and ( S)-1b, are readily applicable to asymmetric alkylation of glycine derivatives with excellent enantioselectivity. In particular, catalyst (S)-1b was found to exhibit a unique temperature effect on the enantioselectivity, and asymmetric alkylation of glycine derivatives at room temperature gave a higher ee than that at 0 degrees C.