A visible-light-driven carboxylation of aryl and alkenyl triflates with CO2 is developed by using a combination of Pd and photoredox catalysts. This reaction proceeds under mild conditions and can be applied to a wide range of substrates including acyclic alkenyl triflates.
Carboxylation of Aryl Triflates with CO<sub>2</sub> Merging Palladium and Visible-Light-Photoredox Catalysts
作者:Samir Kumar Bhunia、Pritha Das、Shantanu Nandi、Ranjan Jana
DOI:10.1021/acs.orglett.9b01532
日期:2019.6.21
visible-light-promoted, highly practical carboxylation of readily accessible aryl triflates at ambient temperature and a balloon pressure of CO2 by the combined use of palladium and photoredox Ir(III) catalysts. Strikingly, the stoichiometric metallic reductant is replaced by a nonmetallic amine reductant providing an environmentally benign carboxylation process. In addition, one-potsynthesis of a carboxylic
Aryl–secondary alkyl cross-coupling with aryl sulfonate esters as coupling partners remains a significant challenge. Efficient cross-coupling between aryl/alkenyl triflates and acyclicsecondary alkylboronic acids is realized for the first time to provide a series of sterically congested acyclicsecondary alkyl arenes/olefins in good to excellent yields. The employment of sterically bulky P,PO ligand L1/L2 is
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
Intermolecular Mizoroki-Heck Reaction of Aliphatic Olefins with High Selectivity for Substitution at the Internal Position
作者:Liena Qin、Xinfeng Ren、Yunpeng Lu、Yongxin Li、Jianrong Steve Zhou
DOI:10.1002/anie.201201806
日期:2012.6.11
New ligand for old reaction: The title reaction of aryltriflates with aliphatic olefins leads to substitution at the internal position with high selectivity. The ratio of the desired isomer (shown in the scheme) to the sum of all other isomers is generally above 10:1. The key to success is the use of a ferrocene bisphosphine ligand (R= 1‐naphthyl). The reaction can be easily scaled up, and minor isomers