6271-80-3Relevant academic research and scientific papers
Agglomeration of Pd0 nanoparticles causing different catalytic activities of Suzuki carbonylative cross-coupling reactions catalyzed by PdII and Pd0 immobilized on dopamine-functionalized magnetite nanoparticles
Long, Yu,Liang, Kun,Niu, Jianrui,Tong, Xin,Yuan, Bing,Ma, Jiantai
, p. 2988 - 2996 (2015/04/14)
Solvent-dispersible magnetite nanoparticles (Fe3O4) end-functionalized with amino groups were successfully prepared by a facile one-pot template-free method to immobilize PdII and Pd0 using a metal adsorption and reduction procedure. They were characterized by TEM, XRD, XPS, FT-IR and VSM. Interestingly, the PdII catalyst exhibited better catalytic activity for carbonylative cross-coupling reactions than the Pd0 catalyst. According to the catalytic activities of a variety of arylboronic acids and aryl iodides catalyzed by two kinds of Pd catalysts, the proposed reaction mechanism of Suzuki carbonylative cross-coupling reactions using the Pd catalyst was also inferred. More importantly, agglomeration of Pd0 nanoparticles was obviously observed in the TEM images of the catalysts after reactions. Therefore, agglomeration of Pd0 nanoparticles should be considered as a significant reason for different catalytic activities of the reactions catalyzed by immobilized PdII and Pd0 catalysts. Furthermore, the PdII catalyst revealed high efficiency and stability during recycling stages.
Toward a continuous-flow synthesis of Boscalid
Glasnov, Toma N.,Kappe, C. Oliver
scheme or table, p. 3089 - 3097 (2011/02/22)
A two-step continuous-flow protocol for the synthesis of 2-amino-4′-chlorobiphenyl, a key intermediate for the industrial preparation of the fungicide Boscalid is described. Initial tetrakis(triphenylphosphine)palladium-catalyzed high-temperature Suzuki-Miyaura cross-coupling of 1-chloro-2-nitrobenzene with 4-chlorophenylboronic acid in a microtubular flow reactor at 160°C using the tert-butanol/water/potassium tert-butoxide solvent/base system provides 4′-chloro-2-nitrobiphenyl in high yield. After in-line scavenging of palladium metal with the aid of a thiourea-based resin, subsequent heterogeneous catalytic hydrogenation is performed over platinum-on-charcoal in a dedicated continuous-flow hydrogenation device. The overall two-step homogeneous/heterogeneous catalytic process can be performed in a single operation providing the desired 2-amino-4′- chlorobiphenyl in good overall yield and high selectivity. Copyright
Biaryl synthesis via Pd-catalyzed decarboxylative coupling of aromatic carboxylates with aryl halides
Goossen, Lukas J.,Rodriguez, Nuria,Melzer, Bettina,Linder, Christophe,Deng, Guojun,Levy, Laura M.
, p. 4824 - 4833 (2008/01/27)
A new strategy for the regiospecific construction of unsymmetrical biaryls is presented, in which easily available salts of carboxylic acids are decarboxylated in situ to give arylmetal species that serve as the nucleophilic component in a catalytic cross-coupling reaction with aryl halides. The catalyst system consists of a copper phenanthroline complex that mediates the extrusion of CO2 from aromatic carboxylates to generate arylcopper species, and a palladium complex that catalyzes the cross-coupling of these intermediates with aryl halides. This bimetallic system allows the direct coupling of various aryl, heteroaryl, or vinyl carboxylic acids with aryl or heteroaryl iodides, bromides, or chlorides at 160°C in the presence of a mild base such as potassium carbonate. The present scope and potential economic impact of the reaction are demonstrated by the synthesis of 42 biaryls, some of which are of substantial industrial relevance. Remaining challenges and future perspectives of the new transformation are discussed.
