The role of imine–enamine tautomerism in effecting cross-aldol condensations
- 作者：James H. Babler ; Matthew C. Atwood ; Jonathan E. Freaney ; Anthony R. Viszlay
- 关键词：Ullmann coupling reaction ; Aminocalixarenes ; Intramolecularly-bridged calixarene
- 刊名：Tetrahedron Letters
- 出版年：2007
- 期刊代码：109_00404039
- 类别：ch
- 出版时间：22 October 2007
- 卷：48
- 期：43
- 页码：7665-7667
- 文件大小：163 K
摘要
An indirect method to effect cross-aldol coupling of two nonequivalent enolizable aldehydes is reported that involves initial conversion of one aldehyde to an imine derivative possessing an N-3° alkyl substituent. In sharp contrast to the related couplings (e.g., the use of α-lithiated imines at low temperature), condensation between the imine and several representative aldehydes occurs readily at ambient temperature in the presence of a catalytic amount of cobalt(II) chloride.