通过独立地优化工艺的两个关键步骤,开发了一种直接从肟和炔烃区域选择性合成高度取代的吡咯的金催化新方法。重要的是,阳离子金(I)物种显示出沿反应路径激活多个步骤,因此可作为多面催化剂。最初由金促进的肟氧向活化的炔烃的添加原位提供了O-乙烯基肟。该Ø随后通过金催化的互变异构,[3,3]-σ重排和环脱水过程将-乙烯基肟转化为吡咯。值得注意的是,该方法提供了酯在3/4位的形式的官能团手柄,以便进一步开发。拟议的机理途径得到了Huisgen环加成点击反应的新应用的支持,该反应被用于探测取代的O-乙烯基肟的相对稳定性。的中间性Ñ -alkenylhydroxylamine ø -乙烯基醚和沿反应途径亚氨基酮或亚氨基醛是由高温测定1 H,2 H ^ { 1个H},和13 C {11 H NMR实验。X射线晶体学证据被用来进一步支持机理假说。
Gold-catalysed rearrangement of O-vinyl oximes for the synthesis of highly substituted pyrroles
作者:Simbarashe Ngwerume、Jason E. Camp
DOI:10.1039/c0cc04372a
日期:——
O-Vinyl oximes were synthesised from the reaction of oximes with activated alkynes and subsequently rearranged using gold catalysis to afford highly substituted pyrroles in an efficient and regiocontrolled process. Additionally, pyrroles were formed directly from oximes and activated alkynes in a multifaceted catalysis process.
Polyethylene glycol (PEG-400) as an efficient and recyclable reaction medium for one-pot synthesis of polysubstituted pyrroles under catalyst-free conditions
Polyethyleneglycol (PEG) was found to be an inexpensive non-toxic and effective medium for the one-pot synthesis of highly functionalized pyrroles. Utilizing this protocol various pyrrole derivatives were synthesized in excellent yields. Environmental acceptability, low cost, high yields, and recyclability of the PEG are the important features of this protocol.
An efficient synthesis of polysubstituted pyrroles via copper-catalyzed coupling of oxime acetates with dialkyl acetylenedicarboxylates under aerobic conditions
A Cu-catalyzed [3+2]-type condensation reaction of oxime acetates and dialkyl acetylenedicarboxylates that provides highly substituted pyrroles under aerobic conditions is described. The newly formed pyrroles are easily employed for further transformations to prepare pyrrolo[2,1-a]isoquinoline skeletons.
The synthesis of polyfunctionalizedpyrroles by reaction of a ketoxime with dimethyl acetylenedicarboxylate using europium(III) triflate as the catalyst is described.
The three-component reactions of phenacyl bromide or its derivatives, amine, and dialkyl acetylenedicarboxylate in the presence of iron(III) chloride as a catalyst at room temperature afforded polysubstituted pyrroles in high yields. polysubstituted pyrroles - three-component reaction - iron(III) chloridePart 283 in the series ‘Studies on Novel Synthetic Methodologies’.