98-08-8Relevant articles and documents
Trifluoromethylation of organic halides with methyl halodifluoroacetates - a process via difluorocarbene and trifluoromethide intermediates
Duan, Jian-Xing,Su, De-Bao,Chen, Qing-Yun
, p. 279 - 284 (1993)
Treatment of methyl halodifluoroacetates, XCF2CO2Me (X=Cl, Br, I), with organic halides RY in the presence of KF and CuI at an appropriate temperature in DMF gave the corresponding trifluoromethylated derivatives, RCF3, in moderate to high yields.A process involving difluorocarbene and trifluoromethide intermediates is suggested.
Aryl-CF3 Coupling from Phosphinoferrocene-Ligated Palladium(II) Complexes
Ferguson, Devin M.,Bour, James R.,Canty, Allan J.,Kampf, Jeff W.,Sanford, Melanie S.
, p. 519 - 526 (2019)
This article describes a detailed investigation of ligand effects on Ph-CF3 coupling from phosphinoferrocene-ligated PdII(Ph)(CF3) complexes. This study reveals that increasing the size of the phosphine substituents results in an enhanced rate of Ph-CF3 coupling, with (DtBPF)Pd(Ph)(CF3) (DtBPF = 1,1′-bis(di-tert-butylphosphino)ferrocene) being the most reactive complex. The mechanism of Ph-CF3 bond formation from both (DtBPF)Pd(Ph)(CF3) and (DiPrPF)Pd(Ph)(CF3) (DiPrPF = 1,1′-bis(diisopropylphosphino)ferrocene) was interrogated experimentally and computationally. These studies implicate a pathway involving concerted Ph-CF3 bond-forming reductive elimination from the four-coordinate PdII centers. An alternative pathway involving α-fluoride elimination and subsequent PhF2C-F coupling from PdII(CF2Ph)(F) intermediates was also evaluated but was ruled out based on DFT as well as the independent synthesis and reactivity studies of (DiPrPF)Pd(CF2Ph)(F).
New Vistas in Transmetalation with Discrete “AgCF3” Species: Implications in Pd-Mediated Trifluoromethylation Reactions
Martínez de Salinas, Sara,Mudarra, ángel L.,Benet-Buchholz, Jordi,Parella, Teodor,Maseras, Feliu,Pérez-Temprano, Mónica H.
, p. 11895 - 11898 (2018)
This work describes the employment of discrete “AgCF3” complexes as efficient transmetalating agents to PdII to surmount overlooked challenges related to the transmetalation step in Pd-catalyzed trifluoromethylation processes. We report the participation of a unique silver ate (Cs)[Ag(CF3)2] complex, under stoichiometric and catalytic conditions, in the unprecedented one-pot formation of PhCF3 using PhI as starting material. Moreover, we show that the transmetalation step, which is often ignored in these transformations, can also determine the success or failure of the coupling process.
Application of Visible-to-UV Photon Upconversion to Photoredox Catalysis: The Activation of Aryl Bromides
Majek, Michal,Faltermeier, Uwe,Dick, Bernhard,Pérez-Ruiz, Raúl,JacobivonWangelin, Axel
, p. 15496 - 15501 (2015)
The activation of aryl-Br bonds was achieved by sequential combination of a triplet-triplet annihilation process of the organic dyes, butane-2,3-dione and 2,5-diphenyloxazole, with a single-electron-transfer activation of aryl bromides. The photophysical and chemical steps were studied by time-resolved transient fluorescence and absorption spectroscopy with a pulsed laser, quenching experiments, and DFT calculations.
Cross-Coupling through Ag(I)/Ag(III) Redox Manifold
Demonti, Luca,Mézailles, Nicolas,Nebra, Noel,Saffon-Merceron, Nathalie
supporting information, p. 15396 - 15405 (2021/10/12)
In ample variety of transformations, the presence of silver as an additive or co-catalyst is believed to be innocuous for the efficiency of the operating metal catalyst. Even though Ag additives are required often as coupling partners, oxidants or halide scavengers, its role as a catalytically competent species is widely neglected in cross-coupling reactions. Most likely, this is due to the erroneously assumed incapacity of Ag to undergo 2e? redox steps. Definite proof is herein provided for the required elementary steps to accomplish the oxidative trifluoromethylation of arenes through AgI/AgIII redox catalysis (i. e. CEL coupling), namely: i) easy AgI/AgIII 2e? oxidation mediated by air; ii) bpy/phen ligation to AgIII; iii) boron-to-AgIII aryl transfer; and iv) ulterior reductive elimination of benzotrifluorides from an [aryl-AgIII-CF3] fragment. More precisely, an ultimate entry and full characterization of organosilver(III) compounds [K]+[AgIII(CF3)4]? (K-1), [(bpy)AgIII(CF3)3] (2) and [(phen)AgIII(CF3)3] (3), is described. The utility of 3 in cross-coupling has been showcased unambiguously, and a large variety of arylboron compounds was trifluoromethylated via [AgIII(aryl)(CF3)3]? intermediates. This work breaks with old stereotypes and misconceptions regarding the inability of Ag to undergo cross-coupling by itself.
Mechanistic Insight into Copper-Mediated Trifluoromethylation of Aryl Halides: The Role of CuI
Jin, Yuxuan,Leng, Xuebing,Liu, He,Shen, Qilong,Wu, Jian
, p. 14367 - 14378 (2021/09/13)
The synthesis, characterization, and reactivity of key intermediates [Cu(CF3)(X)]-Q+ (X = CF3 or I, Q = PPh4) in copper-mediated trifluoromethylation of aryl halides were studied. Qualitative and quantitative studies showed [Cu(CF3)2]-Q+ and [Cu(CF3)(I)]-Q+ were not highly reactive. Instead, a much more reactive species, ligandless [CuCF3] or DMF-ligated species [(DMF)CuCF3], was generated in the presence of excess CuI. On the basis of these results, a general mechanistic map for CuI-promoted trifluoromethylation of aryl halides was proposed. Furthermore, on the basis of this mechanistic understanding, a HOAc-promoted protocol for trifluoromethylation of aryl halides with [Ph4P]+[Cu(CF3)2]- was developed.
Heterogeneously Catalyzed Selective Decarbonylation of Aldehydes by CeO2-Supported Highly Dispersed Non-Electron-Rich Ni(0) Nanospecies
Matsuyama, Takehiro,Yatabe, Takafumi,Yabe, Tomohiro,Yamaguchi, Kazuya
, p. 13745 - 13751 (2021/11/17)
Aldehyde decarbonylation has been extensively investigated, primarily using noble-metal catalysts; however, nonprecious-base-metal-catalyzed aldehyde decarbonylation has been hardly reported. We have established an efficient selective aldehyde decarbonylation reaction with a broad substrate scope and functional group tolerance utilizing a heterogeneous Ni(0) nanospecies catalyst supported on CeO2. The high catalytic performance is attributable to the highly dispersed and non-electron-rich Ni(0) nanospecies, which possibly suppress a side reaction producing esters and adsorbed CO-derived inhibition of the catalytic turnover, according to detailed catalyst characterization and kinetic evaluation.
Photoredox-catalyzed reduction of halogenated arenes in water by amphiphilic polymeric nanoparticles
Eisenreich, Fabian,Kuster, Tom H. R.,Palmans, Anja R. A.,van Krimpen, David
supporting information, (2021/10/05)
The use of organic photoredox catalysts provides new ways to perform metal-free reactions controlled by light. While these reactions are usually performed in organic media, the application of these catalysts at ambient temperatures in aqueous media is of considerable interest. We here compare the activity of two established organic photoredox catalysts, one based on 10-phenylphenothiazine (PTH) and one based on an acridinium dye (ACR), in the light-activated dehalogenation of aromatic halides in pure water. Both PTH and ACR were covalently attached to amphiphilic polymers that are designed to form polymeric nanoparticles with hydrodynamic diameter DH ranging between 5 and 11 nm in aqueous solution. Due to the hydrophobic side groups that furnish the interior of these nanoparticles after hydrophobic collapse, water-insoluble reagents can gather within the nanoparticles at high local catalyst and substrate concentrations. We evaluated six different amphiphilic polymeric nanoparticles to assess the effect of polymer length, catalyst loading and nature of the catalyst (PTH or ACR) in the dechlorination of a range of aromatic chlorides. In addition, we investigate the selectivity of both catalysts for reducing different types of aryl-halogen bonds present in one molecule, as well as the activity of the catalysts for C-C cross-coupling reactions. We find that all polymer-based catalysts show high activity for the reduction of electron-poor aromatic compounds. For electron-rich compounds, the ACR-based catalyst is more effective than PTH. In the selective dehalogenation reactions, the order of bond stability is C-Cl > C-Br > C-I irrespective of the catalyst applied. All in all, both water-compatible systems show good activity in water, with ACR-based catalysts being slightly more efficient for more resilient substrates.
Mechanistic studies into visible light-driven carboxylation of aryl halides/triflates by the combined use of palladium and photoredox catalysts
Caner, Joaquim,Iwasawa, Nobuharu,Martin, Ruben,Murata, Kei,Shimomaki, Katsuya,Toriumi, Naoyuki
supporting information, p. 1846 - 1853 (2021/08/13)
The reaction mechanism of palladium-catalyzed visible light-driven carboxylation of aryl halides and triflates with a photoredox catalyst was examined in detail. Experimental and theoretical studies indicated that the active species for photoredox- catalyzed reduction was cationic ArPd(II)+ species to generate nucleophilic ArPd(I) or its further reduced ArPd(0)- species, which reacted with CO2 to give carboxylic acids. Hydrodehalogenated compounds, main byproducts in this carboxylation, were thought to be generated by protonation of these reduced species.
Photoredox catalysis on unactivated substrates with strongly reducing iridium photosensitizers
Shon, Jong-Hwa,Kim, Dooyoung,Rathnayake, Manjula D.,Sittel, Steven,Weaver, Jimmie,Teets, Thomas S.
, p. 4069 - 4078 (2021/04/06)
Photoredox catalysis has emerged as a powerful strategy in synthetic organic chemistry, but substrates that are difficult to reduce either require complex reaction conditions or are not amenable at all to photoredox transformations. In this work, we show that strong bis-cyclometalated iridium photoreductants with electron-rich β-diketiminate (NacNac) ancillary ligands enable high-yielding photoredox transformations of challenging substrates with very simple reaction conditions that require only a single sacrificial reagent. Using blue or green visible-light activation we demonstrate a variety of reactions, which include hydrodehalogenation, cyclization, intramolecular radical addition, and prenylationviaradical-mediated pathways, with optimized conditions that only require the photocatalyst and a sacrificial reductant/hydrogen atom donor. Many of these reactions involve organobromide and organochloride substrates which in the past have had limited utility in photoredox catalysis. This work paves the way for the continued expansion of the substrate scope in photoredox catalysis.
