作者:D. Chianelli、L. Testaferri、M. Tiecco、M. Tingoli
DOI:10.1016/0040-4020(82)80207-x
日期:1982.1
The reactions of dioxanyl and cyclohexyl radicals with 2- and 3-X-pyridines (X = CN, COMe, CO2Me) give a single substitution product deriving by addition at the 5- and 6-positions respectively; with 4-X-pyridines substitution occurs preferentially at the 3-position. If the reactions are carried out with protonated pyridines other positional isomers are obtained. From the synthetic point of view the
二恶烷基和环己基与2-和3-X-吡啶(X = CN,COMe,CO 2 Me)的反应产生单个取代产物,分别通过在5-位和6-位加成而得;具有4-X-吡啶的取代优先发生在3-位。如果反应用质子化吡啶进行,则获得其他位置异构体。因此,从综合的观点来看,这两种程序是互补的。基于添加步骤的过渡态的不同性质,讨论和解释了从未质子化的质子到质子化的芳族质的传递时位置选择性的变化。