通过初始速率法获得了钯(II)催化的苯基硼酸与乙基噻吩-3-乙酸乙酯之间的氧化交叉偶联中关键组分的反应顺序。结果表明,反应速率不仅取决于三氟乙酸钯(反应顺序:0.97)和苯基硼酸(反应顺序:1.26)的浓度,还取决于噻吩(反应顺序:0.55)和氧化银(浓度)的浓度。反应顺序:-1.27)。NMR光谱滴定研究确定了银盐与苯基硼酸和噻吩-3-基乙基乙酸乙酯之间存在1:1的络合物。低反向动力学同位素效应(k H / k D= 0.93)是通过使用乙基噻吩-3-乙酸乙基酯的4氘代异构体并监测其与4-苯基取代产物的反应而确定的。用对位取代的2-苯基噻吩进行的Hammett分析得出与苯基硼酸的氧化交叉偶联的负ρ值。根据动力学数据和其他证据,提出了一种机制,该机制可以将苯基从苯基硼酸转移到三氟乙酸钯和噻吩的1:1络合物中,作为速率确定步骤。提出并讨论了有关中间体的结构。
Pd/C as a Catalyst for Completely Regioselective CH Functionalization of Thiophenes under Mild Conditions
作者:Dan-Tam D. Tang、Karl D. Collins、Johannes B. Ernst、Frank Glorius
DOI:10.1002/anie.201309305
日期:2014.2.10
The completely C3‐selective arylation of thiophenes and benzo[b]thiophenes was achieved by using Pd/C as a heterogeneous catalyst without ligands or additives undermild reaction conditions. The practicability of this transformation is demonstrated by notable functional group tolerance and the insensitivity of the reaction to H2O and air. This method is also applicable to nitrogen‐ and oxygen‐containing
通过在温和的反应条件下使用Pd / C作为不带配体或添加剂的非均相催化剂,可以实现噻吩和苯并[ b ]噻吩的完全C3选择性芳基化。该转化的实用性通过显着的官能团耐受性和反应对H 2 O和空气的不敏感性得到证明。该方法也适用于含氮和氧的杂环,产生相应的C2芳基化产物。三相试验以及汞中毒和热过滤试验表明,催化活性物质在性质上是异质的。
Pd-Catalyzed β-Selective Direct C–H Bond Arylation of Thiophenes with Aryltrimethylsilanes
作者:Kenji Funaki、Tetsuo Sato、Shuichi Oi
DOI:10.1021/ol3029109
日期:2012.12.21
Direct arylation of thiophenes and benzothiophenes with aryltrimethylsilanes was effectively catalyzed by PdCl2(MeCN)2 in the presence of CuCl2 as an oxidant. The reaction preferentially occurred at the β-position of both thiophenes and benzothiophenes.
Transition-Metal-Free Sulfuration/Annulation of Alkenes: Economical Access to Thiophenes Enabled by the Cleavage of Multiple C–H Bonds
作者:Liang Chen、Hao Min、Weilan Zeng、Xiaoming Zhu、Yun Liang、Guobo Deng、Yuan Yang
DOI:10.1021/acs.orglett.8b03078
日期:2018.12.7
and transition-metal-free strategy for the synthesis of thiophenes from substituted buta-1-enes with potassium sulfide has been presented. The reaction achieves double C–Sbondformations via cleavage of multiple C–H bonds and provides an efficientapproach to access various functionalized thiophenes. Moreover, the strategy can also be used for the synthesis of thiophenes from 1,4-diaryl-1,3-dienes.