Counterion effects in iminium-activated electrophilic aromatic substitutions of pyrroles
作者:Sami Lakhdar、Herbert Mayr
DOI:10.1039/c0cc04295a
日期:——
Electrophilic substitution of pyrroles by alpha,beta-unsaturated iminium ions is slow in acetonitrile when only weakly basic counterions are present. When the reactions are carried out in the presence of KCF(3)CO(2), fast deprotonation of the intermediate sigma-adducts occurs, and the rate constant for the rate-determining CC bond-forming step can be predicted from the electrophilicity parameter E
当仅存在弱碱性的抗衡离子时,乙腈中的α,β-不饱和亚胺离子对吡咯的亲电取代作用较慢。当反应在KCF(3)CO(2)存在下进行时,中间sigma加合物发生快速去质子化,并且可以从亲电性参数预测决定速率的CC键形成步骤的速率常数亚胺离子的E和吡咯的N和s参数。