Reaction of hydrazones derived from active methylene compounds with Vilsmeier–Haack reagent
作者:Sergey P. Ivonin、Bohdan B. Kurpil’、Oleksandr O. Grygorenko、Dmitry M. Volochnyuk
DOI:10.1007/s00706-014-1293-7
日期:2014.12
ester, nitrile, triphenylphosphonium, and phthalimide moieties were evaluated. It was found that electron-withdrawing and steric effects provided by the substituent at α position strongly influenced the regioselectivity of the reaction. Increasing mesomeric electron-withdrawing effect of this group favors the formation of functionalized 1,3,4-trisubstituted pyrazoles as compared to 1,3-disubstituted
摘要研究了衍生自活性亚甲基化合物的与Vilsmeier-Haack试剂的反应。评价了具有砜,酯,腈,三苯基phosph和邻苯二甲酰亚胺基团的化合物。发现由α位上的取代基提供的吸电子和空间效应强烈影响反应的区域选择性。与1,3-二取代的吡唑-4-甲醛相比,该基团的介晶吸电子作用的增加有利于官能化的1,3,4-三取代的吡唑的形成。相反,增强的位阻和降低的吸电子效应使平衡向1,3-二取代的吡唑-4-甲醛释放。其他因素,例如the氮原子上的取代基以及试剂比例, 图形概要