A general palladium-catalyzedreductivecarbonylation of aryl triflates in the presence of synthesis gas (CO/H 2 ) has been developed. The reaction with this most simple and environmentally benign formylation source proceeds under mild conditions and various aromatic aldehydes have been prepared in good to high yield.
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
Palladium-Catalyzed Difluoromethylation of Aryl Chlorides and Triflates and Its Applications in the Preparation of Difluoromethylated Derivatives of Drug/Agrochemical Molecules
作者:Changhui Lu、Hao Lu、Jiang Wu、Hong C. Shen、Taishan Hu、Yucheng Gu、Qilong Shen
DOI:10.1021/acs.joc.7b02989
日期:2018.1.19
A palladium-catalyzed difluoromethylation of a series of arylchlorides and triflates under mild conditions was described. A variety of common functional groups were tolerated. In addition, by using this protocol, several drug molecules containing an arylchloride unit were successfully difluoromethylated, thus enabling medicinal chemists to rapidly access novel drug derivatives with potentially improved
Donor-Acceptor Interactions in Red-Emitting Thienylbenzene-Branched Dendrimers with Benzothiadiazole Core
作者:K. R. Justin Thomas、Tai-Hsiang Huang、Jiann T. Lin、Shin-Chien Pu、Yi-Ming Cheng、Cheng-Chih Hsieh、Chou Pi Tai
DOI:10.1002/chem.200801694
日期:2008.12.8
characterization of dendrimers containing thienylbenzene repeating units, red-emittingbenzothiadiazolecore, and triarylamine peripheries that bear naphthyl units are reported. The relevant dendrimers of different generations are classified as G(nb) (n=1-3), while the tert-butyl dendrimers G(na) with the acceptor alone were also synthesized to serve as control chromophores that avoid donor-acceptor interactions
Enantioselective α-Arylation of Ketones with Aryl Triflates Catalyzed by Difluorphos Complexes of Palladium and Nickel
作者:Xuebin Liao、Zhiqiang Weng、John F. Hartwig
DOI:10.1021/ja074453g
日期:2008.1.1
90%. Systematic studies on these alpha-arylations have revealed a number of factors that affect enantioselectivity. Ligands containing biaryl backbones with smaller dihedralangles generate catalysts that react with higher enantioselectivity than related ligands with largerdihedralangles. In addition, faster rates for reactions of aryl triflates versus those for reactions of aryl bromides allow the