Transition-Metal-Free C–C, C–O, and C–N Cross-Couplings Enabled by Light
作者:Wenbo Liu、Jianbin Li、Pierre Querard、Chao-Jun Li
DOI:10.1021/jacs.9b02684
日期:2019.4.24
and nitriles without the assistance of metal catalysts empowered by photoenergy. Control experiments reveal that among all common aryl electrophiles only aryl triflates are competent in these couplings whereas aryl iodides and bromides cannot serve as the coupling partners. DFT calculation reveals that once converted to the aryl radical cation, aryl triflate would be more favorable to ipso substitution
用于构建 CC、CO 和 CN 键的过渡金属催化交叉偶联已经彻底改变了化学科学。尽管取得了巨大的成就,但这些金属催化剂也存在一些问题,包括成本高、需要专门的配体、对空气和水分的敏感性以及所谓的“过渡金属残留问题”。不依赖于成熟的氧化加成、金属转移和还原消除机制范式的互补策略可能会消除所有这些与金属相关的问题。在此,我们表明芳基三氟甲磺酸酯可以与芳基三氟硼酸钾、脂肪醇和腈偶联,而无需借助光能赋能的金属催化剂。对照实验表明,在所有常见的芳基亲电试剂中,只有芳基三氟甲磺酸酯能够进行这些偶联,而芳基碘化物和溴化物不能作为偶联伙伴。DFT 计算表明,一旦转化为芳基自由基阳离子,芳基三氟甲磺酸酯将更有利于 ipso 取代。荧光光谱和循环伏安法研究表明,激发态丙酮和芳基三氟甲磺酸酯之间的相互作用对于这些偶联是必不可少的。预计本报告中的结果将为执行交叉耦合提供新的机会。荧光光谱和循环伏安法研究表明,激发态
Regioselective Threefold Aromatic Substitution of Benzoic Acid Derivatives by Dearomatization, Regioselective Functionalization, and Rearomatization
作者:Eva Koch、Armido Studer
DOI:10.1002/anie.201300259
日期:2013.4.26
Ipso, meta, and para: Benzoic acid derivatives can be highly regioselectively substituted at the ipso, meta, and para positions. The reaction sequence comprises an alkylative Birchreduction, a 4‐alkylation, a palladium‐catalyzed γ‐arylation, and an oxidative rearomatization (see scheme). All the reactions are robust and experimentally easy to conduct.