Reactions of Nitroheteroarenes with Carbanions: Bridging Aromatic, Heteroaromatic, and Vinylic Electrophilicity
作者:Florian Seeliger、Sylwia Błażej、Sebastian Bernhardt、Mieczysław Mąkosza、Herbert Mayr
DOI:10.1002/chem.200800329
日期:2008.7.7
reactive than nitrobenzene. Among the five-membered heterocycles 2-nitrothiophene is the most active followed by nitroimidazoles and 4-nitropyrazole. Nitropyrroles are the least electrophilic nitroheteroarenes with reactivities comparable to nitrobenzene. Quantum chemically calculated methyl anion affinities (B3LYP/6-311G(d,p)//B3LYP/6-31G(d)) of the nitroarenes correlated only moderately with the partial
已确定氯甲基苯基砜(1-)的阴离子被各种硝基杂芳烃(例如硝基吡啶,硝基吡咯,硝基咪唑,2-硝基噻吩和4-硝基吡唑)的取代亲核取代(VNS)的相对速率常数通过竞争实验。结果表明,硝基吡啶的活性比硝基苯高大约四个数量级。在五元杂环中,2-硝基噻吩活性最高,其次是硝基咪唑和4-硝基吡唑。硝基吡咯是亲电性最低的硝基杂芳烃,其反应性与硝基苯相当。量子化学计算的硝基芳烃的甲基阴离子亲和力(B3LYP / 6-311G(d,p)// B3LYP / 6-31G(d))仅与部分相对速率常数适度相关。这些活性与硝基芳烃的LUMO能的相关性甚至更差。通过测量1-硝基芳烃和二乙基亚芳基丙二酸酯10的二阶速率常数,可以将硝基杂芳烃的亲电反应性与基于线性自由能关系log k(K)的综合亲电等级联系起来。 20摄氏度)= s(N + E)。