Mild and efficient boronic acid catalysis of Diels–Alder cycloadditions to 2-alkynoic acids
摘要:
The concept of boronic acid catalysis (BAC) for the activation of unsaturated carboxylic acids is applied to the Diels-Alder cycloaddition between 2-alkynoic acids as dienophiles and various dienes. These [4+2] cycloadditions produce cyclohexadienyl carboxylic acids, which can be oxidized in situ to produce polysubstituted aromatic carboxylic acids. The boronic acid catalyst is suspected to provide activation by a LUMO-lowering effect of the unsaturated carboxylic acid likely via a covalent, monoacylated hemiboronic ester intermediate. (C) 2010 Elsevier Ltd. All rights reserved.
Mild and efficient boronic acid catalysis of Diels–Alder cycloadditions to 2-alkynoic acids
作者:Hongchao Zheng、Dennis G. Hall
DOI:10.1016/j.tetlet.2010.04.132
日期:2010.7
The concept of boronic acid catalysis (BAC) for the activation of unsaturated carboxylic acids is applied to the Diels-Alder cycloaddition between 2-alkynoic acids as dienophiles and various dienes. These [4+2] cycloadditions produce cyclohexadienyl carboxylic acids, which can be oxidized in situ to produce polysubstituted aromatic carboxylic acids. The boronic acid catalyst is suspected to provide activation by a LUMO-lowering effect of the unsaturated carboxylic acid likely via a covalent, monoacylated hemiboronic ester intermediate. (C) 2010 Elsevier Ltd. All rights reserved.