Enantioselective and Diastereoselective Mukaiyama−Michael Reactions Catalyzed by Bis(oxazoline) Copper(II) Complexes
作者:David A. Evans、Karl A. Scheidt、Jeffrey N. Johnston、Michael C. Willis
DOI:10.1021/ja010302g
日期:2001.5.1
two-point binding of the imide substrate and can be viewed as an extension of substrate enantioselection in the corresponding Diels-Alder reactions. A model analogous to the one employed to describe the hetero Diels-Alder reaction is proposed to account for the observed relation between enolsilane geometry and product absolute diastereocontrol. Insights into modes of catalyst inactivation are given, including
使用 [Cu((S,S)-t-Bu-box)](SbF6)2 (1a) 作为路易斯酸催化剂,开发了烯醇硅烷对不饱和酰亚胺衍生物的高度对映选择性和非对映选择性迈克尔加成的范围。这些添加的产物是有用的合成子,包含能够在温和条件下分化的末端。迈克尔受体 pi 面选择性与酰亚胺底物的两点结合一致,可以看作是相应 Diels-Alder 反应中底物对映选择的延伸。提出了一种类似于用于描述异狄尔斯-阿尔德反应的模型来解释烯醇硅烷几何形状与产物绝对非对映控制之间的观察关系。给出了对催化剂失活模式的见解,包括在反应过程中产生的二氢吡喃中间体抑制催化剂的光谱证据。公开了一种方法,其中使用醇添加剂水解抑制性二氢吡喃并在显着缩短的反应时间内提供去甲硅烷基化的迈克尔加合物。
Catalytic Enantioselective Michael Additions to Unsaturated Ester Derivatives Using Chiral Copper(II) Lewis Acid Complexes
作者:David A. Evans、Michael C. Willis、Jeffrey N. Johnston
DOI:10.1021/ol9901570
日期:1999.9.1
[formula: see text] Chiral Cu(II) bisoxazoline (box) Lewisacids have been developed as catalysts of the Michael addition of enolsilanes to unsaturated ester derivatives. While enantioselection is stereoregular, the sense of diastereoselection is directly related to thioester enolsilane geometry: (E) enolsilanes give anti adducts and (Z) enolsilanes afford syn adducts. The size of the enolsilane alkylthio