Structural effects on the reactivity of carbon radicals in homolytic aromatic substitution. Part 4. The nucleophilicity of bridgehead radicals
作者:M. Fiorentino、L. Testaferri、M. Tiecco、L. Troisi
DOI:10.1039/p29770000087
日期:——
state of the addition step of the radicals to the protonated substrates, as a consequence of different ring strain in the three polycyclic systems. A comparison of the present results with those already available for other alkyl radicals is also reported, in order to evaluate the effect of electronic configuration on the reactivity of carbon radicals in homolytic aromatic substitution.
1-金刚烷基(1),3,3-二甲基双环[2.2.2]辛-1-基(2)和7,7-二甲基双环[2.2.1]庚-1-基(3)与对质子化吡啶和喹啉进行了研究,并确定了相对取代率。所得结果表明,三个桥头基具有亲核性质,其亲核性质依次为:(1)>(2)>(3)。基于在三个多环系统中不同的环应变,在自由基向质子化底物加成步骤的过渡态中,电荷的不同程度的发展,可以解释这种行为。还报告了将目前的结果与其他烷基已经获得的结果进行比较,