hemimalonate used. With the unsubstituted substrate, a carboxylic acid intermediate was isolated upon acid quench resulting from the nucleophilic addition of the putative enol carboxylate anion of the hemimalonate to imines/aldehydes before CO2 loss. With substituted hemimalonates, the reaction likely involved an enolate which then added to imines/aldehydes or was competitively protonated. According to the base
N-Heterocyclic carbene mediated Reformatsky reaction of aldehydes with α-trimethylsilylcarbonyl compounds
作者:Xiao-Lei Zou、Guang-Fen Du、Wan-Fu Sun、Lin He、Xiao-Wei Ma、Cheng-Zhi Gu、Bin Dai
DOI:10.1016/j.tet.2012.11.015
日期:2013.1
N-Heterocycliccarbenes have been employed as highly efficient organocatalysts to mediate silyl-Reformatsky type reaction. In the presence of only 0.5 mol % nucleophiliccarbene 1, various aldehydes coupled with α-trimethylsilylethylacetate very smoothly in DMF at room temperature to provide the corresponding β-hydroxyesters in moderate to high yields. α-Trimethylsilylketone and α-trimethylsilylamide