58743-78-5Relevant articles and documents
The site-selectivity and mechanism of Pd-catalyzed C(sp2)-H arylation of simple arenes
Kim, Daeun,Choi, Geunho,Kim, Weonjeong,Kim, Dongwook,Kang, Youn K.,Hong, Soon Hyeok
, p. 363 - 373 (2021/01/14)
Control over site-selectivity is a critical challenge for practical application of catalytic C-H functionalization reactions in organic synthesis. Despite the seminal breakthrough of the Pd-catalyzed C(sp2)-H arylation of simple arenes via a concerted metalation-deprotonation (CMD) pathway in 2006, understanding the site-selectivity of the reaction still remains elusive. Here, we have comprehensively investigated the scope, site-selectivity, and mechanism of the Pd-catalyzed direct C-H arylation reaction of simple arenes. Counterintuitively, electron-rich arenes preferably undergo meta-arylation without the need for a specifically designed directing group, whereas electron-deficient arenes bearing fluoro or cyano groups exhibit high ortho-selectivity and electron-deficient arenes bearing bulky electron-withdrawing groups favor the meta-product. Comprehensive mechanistic investigations through a combination of kinetic measurements and stoichiometric experiments using arylpalladium complexes have revealed that the Pd-based catalytic system works via a cooperative bimetallic mechanism, not the originally proposed monometallic CMD mechanism, regardless of the presence of a strongly coordinating L-type ligand. Notably, the transmetalation step, which is influenced by a potassium cation, is suggested as the selectivity-determining step.
Palladium Palladium Nanoparticles Nanoparticles Supported Supported on β-cyclodextrin on β-Cyclodextrin Functionalised Functionalized Poly(amido Poly(amidoamine)s amine)s and their and Application Their Application in Suzuki-Miyaura in Suzuki-Miyaura Cross-Coupling Cross-Coupling Reactions Reactions
Zhang, Wei,Yao, Zi-Jian,Deng, Wei
, p. 1667 - 1677 (2019/10/01)
Herein, the synthesis, characterization and catalytic application of an organic-inorganic, palladium (Pd)-containing hybrid material, poly(amidoamine)-cyclodextrin (Pd@PAAs-CD), is reported as an efficient catalyst for Suzuki-Miyaura coupling reactions. The structure of Pd@PAAs-CD was confirmed by Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), inductively-coupled plasma atomic emission spectroscopy (ICP-AES), and 1H nuclear magnetic resonance (NMR) spectroscopy. Furthermore, an efficient protocol has been developed using Pd@PAAs-CD as the catalyst in a Suzuki-Miyaura cross-coupling reaction in an aqueous medium in high yields. By using cyclodextrin (CD) as the mediator grafted onto PAAs, the Pd nanoparticles (NPs) were dispersed and enhanced the catalytic reaction by promoting host-guest interactions with the CD. In addition, the reusability of the Pd@PAAs-CD hybrid material is demonstrated for use in multiple sequential cross-coupling reactions.
CuPd nanoparticles as a catalyst in carbon-carbon cross-coupling reactions by a facile oleylamine synthesis
Smith, Sarah E.,Siamaki, Ali R.,Gupton, B. Frank,Carpenter, Everett E.
, p. 91541 - 91545 (2016/10/11)
CuPd bi-metallic nanoparticles were synthesized in oleylamine without the use of additional surfactants, ligands, or reducing agents. The alloyed nanoparticles showed high catalytic activity in Suzuki cross-coupling reactions with excellent turnover number (6000) and turnover frequency of 72:000 h-1 under microwave irradiation. These nanoparticles were successfully utilized in a Suzuki coupling reaction with a diverse range of functionalized substrates. The catalyst also demonstrated multiple recyclability for Suzuki coupling reactions. The CuPd nanoparticles have also probed the utility in other cross-coupling reactions such as Heck and Sonogashira coupling reactions. According to the XPS data, two oxidation states of each metal exist on the surface of the nanoparticle. This is advantageous especially for Sonogashira cross-coupling reactions because having Cu+ present on the surface of the catalyst eliminates the need for a copper salt to stabilize the alkyne during the reaction.
