The role of cesium fluoride in aryl propargyl ether Claisen rearrangement and its mechanistic elucidation: a theoretical study

详细信息    查看全文

• 作者：Mengistu Gemech Menkir ; Venkatesan Srinivasadesikan ; Shyi-Long Lee
• 关键词：Cesium fluoride ; Aryl propargyl ether ; Claisen rearrangement ; Density functional theory ; Benzofuran
• 刊名：Structural Chemistry
• 出版年：2016
• 出版时间：October 2016
• 年：2016
• 卷：27
• 期：5
• 页码：1383-1393
• 全文大小：1,607 KB
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Chemistry
  Computer Applications in Chemistry
  Physical Chemistry
  Theoretical and Computational Chemistry
  
• 出版者：Springer Netherlands
• ISSN：1572-9001
• 卷排序：27

文摘

The role of cesium fluoride (CsF) in aryl propargyl ether Claisen rearrangement and its mechanistic pathway have been investigated in gas and solvent phase using the density functional theory implemented in Gaussian 09. Our results indicate that the [3,3]-sigmatropic rearrangement is the rate-limiting step with ΔG‡ value of 37.1 kcal/mol in solvent phase. Furthermore, the results show that the enolization of α-allenylketone intermediate (Int1-CsF) has a higher free energy barrier, which implies that the formation of benzopyran is not favored in the presence of CsF. However, the abstraction of the α-hydrogen atom in Int1-CsF with CsF shows a very low free energy barrier and is the most favored pathway for aryl propargyl ether Claisen rearrangement in the presence of CsF to form benzofuran. In the case of substituted aryl propargyl ethers, a methoxy group on the benzene ring lowers the activation barrier. The HOMO–LUMO, conformational and NBO analysis indicate that increasing methyl substitution on the propargyl residue enhances the rearrangement reaction.