Intramolecular and Intermolecular Kinetic Isotope Effects (KIE) in the Nitrosoarene Ene Reaction: Experimental Evidence for Reversible Intermediate Formation
作者:Waldemar Adam、Oliver Krebs、Michael Orfanopoulos、Manolis Stratakis、Georgios C. Vougioukalakis
DOI:10.1021/jo0266240
日期:2003.3.1
The intramolecular and intermolecular kinetic isotope effects (KIE) have been determined for the nitrosoarene ene reaction with deuterium-stereolabeled 2,3-dimethyl-2-butenes (TME). trans-TME-d(6) (k(H)/k(D) = 3.0) and gem-TME-d(6) (k(H)/k(D) = 4.0) show large intramolecular primary isotope effects. In contrast, the intramolecular competition in cis-TME-d(6) (k(H)/k(D) = 1.5) and the intermolecular
已经确定了亚硝基芳烃与氘-立体标记的2,3-二甲基-2-丁烯(TME)的分子内和分子间动力学同位素效应(KIE)。trans-TME-d(6)(k(H)/ k(D)= 3.0)和gem-TME-d(6)(k(H)/ k(D)= 4.0)显示出较大的分子内一级同位素效应。相反,顺式-TME-d(6)的分子内竞争(k(H)/ k(D)= 1.5)和TME-d(0)/ TME-d(12)对的分子间竞争(k (H)/ k(D)= 1.98)显示的小得多,但在机械上具有显着的动力学同位素效应。就在反应的第一步中可逆地形成三元环中间体,即氮丙啶N-氧化物或类似的不对称极化双自由基而言,后一个事实是合理的。