Intramolecular Assistance of Electron Transfer from Heteroatom Compounds. Electrochemical Oxidation of 2-(2-Pyridyl)ethyl-Substituted Ethers, Sulfides, and Selenides
作者:Mitsuru Watanabe、Seiji Suga、Jun-ichi Yoshida
DOI:10.1246/bcsj.73.243
日期:2000.1
Organoheteroatom compounds having a 2-(2-pyridyl)ethyl group were synthesized and their oxidation potentials were determined by rotating disk electrode voltammetry. The oxidation potentials were found to be less positive than those of the corresponding compounds having a phenyl group in place of the pyridyl group. The dynamic coordination of the pyridyl group to the heteroatom, which stabilizes the
合成了具有 2-(2-吡啶基)乙基的有机杂原子化合物,并通过旋转圆盘电极伏安法测定了它们的氧化电位。发现氧化电位低于具有苯基代替吡啶基的相应化合物的氧化电位。吡啶基与杂原子的动态配位稳定了阳离子自由基中间体,似乎是促进电子转移的原因。分子内辅助的量级随着母体化合物氧化电位的增加而增加。这种趋势可以用吡啶氮的非键合 p 轨道和母体杂原子化合物的 HOMO 之间的能量匹配来解释。
Aerial dioxygen activation <i>vs.</i> thiol–ene click reaction within a system
作者:Khokan Choudhuri、Arkalekha Mandal、Prasenjit Mal
DOI:10.1039/c8cc01359d
日期:——
Markovnikov or anti-Markovnikov selective thiol–ene click (TEC) reactions and the synthesis of β-hydroxysulfides via aerial dioxygen activation are prevalent C–S bond forming reactions of styrenes and thiophenols. Herein, by choosing appropriate environments using solvents with additives or neat conditions, any one of these three reactions was achieved exclusively in excellent yields.
cobaloxime to produce olefins and H2. This operationally simple method enables direct dehydrogenation of readily available chemical feedstocks to diversely functionalized olefins. For example, we demonstrate, for the first time, the oxidant-free desaturation of thioethers and amides to alkenyl sulfides and enamides, respectively. Moreover, the system’s exceptional siteselectivity and functional group
脂肪族催化脱氢 (CDA) 在有机合成中的价值在很大程度上仍未得到充分探索。已知的均相 CDA 系统通常需要使用牺牲氢受体(或氧化剂)、贵金属催化剂和苛刻的反应条件,因此将大多数现有方法限制为非或低官能化烷烃的脱氢。在这里,我们描述了一种可见光驱动的双催化剂系统,该系统由廉价的有机光氧化还原和贱金属催化剂组成,用于室温、无受体 CDA (Al-CDA)。该过程由光激发的 2-氯蒽醌引发,涉及脂肪族的 H 原子转移 (HAT) 形成烷基自由基,然后与钴肟反应生成烯烃和 H 2. 这种操作简单的方法能够将容易获得的化学原料直接脱氢成多种官能化的烯烃。例如,我们首次证明了硫醚和酰胺在无氧化剂条件下分别脱饱和为烯基硫醚和烯酰胺。此外,14 种生物相关分子和药物成分的后期脱氢和合成说明了该系统卓越的位点选择性和官能团耐受性。机理研究揭示了双重 HAT 过程,并提供了对反应性和位点选择性起源的见解。