Palladium-Catalyzed Arylation of Trimethylsilyl Enolates of Esters and Imides. High Functional Group Tolerance and Stereoselective Synthesis of 
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- 作者：Xiaoxiang Liu and John F. Hartwig
- 刊名：Journal of the American Chemical Society
- 出版年：2004
- 出版时间：April 28, 2004
- 年：2004
- 卷：126
- 期：16
- 页码：5182 - 5191
- 全文大小：200K
- 年卷期：v.126,no.16(April 28, 2004)
- ISSN：1520-5126
文摘
A general procedure for the palladium-catalyzed arylation of trimethylsilyl enolates of esters andimides is reported. In the presence of ZnF2 or Zn(O-t-Bu)2 as an additive, the trimethylsilyl enolates ofesters, including those bearing 
-alkoxy derivatives, underwent arylation in high yield with high functionalgroup tolerance. This arylation chemistry was extended to ester derivatives bearing chiral auxiliaries toform new tertiary stereocenters. The arylation of imides bearing the Evans auxiliary proceeded withselectivities up to 90% de. Further, the arylation of the ketal developed by Ley provided -aryl glycolateswith excellent diastereoselectivities (90 to >98% de). This reaction provides a convenient route to thesynthesis of enantiopure -aryl--hydroxy esters. Reactions conducted with Zn(O-t-Bu)2 as an additiveoccurred at room temperature to give enhanced diastereoselectivities with both chiral reagents. Mechanisticstudies showed that the reaction conditions are neutral enough that the observed diastereomeric ratiosreflect kinetic selectivities.
-alkoxy derivatives, underwent arylation in high yield with high functionalgroup tolerance. This arylation chemistry was extended to ester derivatives bearing chiral auxiliaries toform new tertiary stereocenters. The arylation of imides bearing the Evans auxiliary proceeded withselectivities up to 90% de. Further, the arylation of the ketal developed by Ley provided -aryl glycolateswith excellent diastereoselectivities (90 to >98% de). This reaction provides a convenient route to thesynthesis of enantiopure -aryl--hydroxy esters. Reactions conducted with Zn(O-t-Bu)2 as an additiveoccurred at room temperature to give enhanced diastereoselectivities with both chiral reagents. Mechanisticstudies showed that the reaction conditions are neutral enough that the observed diastereomeric ratiosreflect kinetic selectivities.