35572-38-4Relevant academic research and scientific papers
Phenoxy-Linked Mesoionic Triazol-5-ylidenes as Platforms for Multinuclear Transition Metal Complexes
Mendoza-Espinosa, Daniel,González-Olvera, Rodrigo,Negrón-Silva, Guillermo E.,Angeles-Beltrán, Deyanira,Suárez-Castillo, Oscar R.,álvarez-Hernández, Alejandro,Santillan, Rosa
, p. 4529 - 4542 (2015)
The preparation and full characterization of a variety of mono- ([L1-H]), di- ([L2-H2], [L2A-H2]), and tri- ([L3-H3]) 1,2,3-triazolium salts constructed form "clicked" hydroxybenzene derivatives are reported. Deprotonation with potassium hexamethyldisilazide, followed by in situ metalation, allowed for the synthesis of a series of mono- (L1·[M]), di- (L2·[M]2, L2·[M]2), and trinuclear (L3·[M]3) group 9-11 (M = [Rh(CO)2Cl], [Pd(allyl)Cl], and [AuCl]) triazol-5-ylidene metal complexes. In solution, all metal complexes feature symmetrical patterns displaying C2 and C3 fold axes when supported by di- and tritriazol-5-ylidene ligands. The vibration frequencies of Ln·[Rh(CO)2Cl]n (n = 1-3) complexes indicate that the electron-donor properties of the new ligands are comparable to those for previously reported MIC complexes and superior to classical NHCs. Prompting coordination of the vicinal phenoxy group to the metal centers proved unsuccessful after treatment of the Ln·[Rh(CO)2Cl]n and Ln·[Pd(allyl)Cl]n (n = 1-3) precursors with AgBF4; the expected chelated cationic complexes were highly unstable, indicating a weak or no coordination availability through the oxygen atom. Crystal structures of the complexes L1·[AuI] and L2A·[Pd(allyl)I]2 illustrated the metal center geometrical environment and confirmed the lack of coordination through the phenoxy moiety of the ligand. Preliminary catalytic trials established the enhanced performance of di- and trimetallic palladium complexes in cross-coupling reactions and the intramolecular cyclization of enynes catalyzed by gold complexes.
Reactions of nitrogen donors with cycloheptatrienylidene complexes: Metal coordination versus nucleophilic attack on the carbene ligand
Mantas-Oektem, Kevser,Oefele, Karl,Poethig, Alexander,Bechlars, Bettina,Herrmann, Wolfgang A.,Kuehn, Fritz E.
, p. 8249 - 8256 (2012)
Cycloheptatrienylidene (CHT)-palladium complexes may react with N-donor molecules, showing two different pathways of reaction, either nucleophilic attack on the CHT ligand or coordination to the metal center. The first variant leads to a formation of wate
α-Arylation of (hetero)aryl ketones in aqueous surfactant media
Gallou, Fabrice,Lipshutz, Bruce H.,Roa, Daniel E.,Wood, Alex B.
supporting information, p. 4858 - 4865 (2021/07/12)
α-Arylation reactions can be performed in water, enabled by a designer surfactant,under mild conditions and in the absence of organic co-solvents. A multitude of aryl and heteroaryl ketones are amenable to coupling with functionalized aryl halides. Use of a lipophilic base that can gain entry to the micellar inner cores mediates enolization. In some cases, palladium loadings as low as 2500 ppm (0.25 mol%) are sufficient for coupling in a completely recyclable medium, exemplifying chemistry in water.
Carbene-Catalyzed Alkylation of Carboxylic Esters via Direct Photoexcitation of Acyl Azolium Intermediates
Ren, Shi-Chao,Lv, Wen-Xin,Yang, Xing,Yan, Jia-Lei,Xu, Jun,Wang, Fang-Xin,Hao, Lin,Chai, Huifang,Jin, Zhichao,Chi, Yonggui Robin
, p. 2925 - 2934 (2021/03/09)
A carbene-catalyzed reductive coupling reaction of carboxylic esters and substituted Hantzsch esters is disclosed. Key steps of this reaction include one-electron reduction of a carbene catalyst-bound acyl azolium intermediate to generate the corresponding radical intermediate for subsequent alkylation reactions. The reaction is promoted by irradiation with visible light without the involvement of transition-metal photocatalysts. Mechanistic studies suggest that direct photoexcitation of the in situ formed acyl azolium intermediate is likely responsible for this light-induced one-electron-reduction process. Photoexcitation converts the acyl azolium intermediate to a single-electron oxidant, enabling single-electron oxidation of Hantzsch esters to generate radical intermediates. Our reactions work well for a broad range of aryl carboxylic ester and Hantzsch ester substrates. Sophisticated structures, including those present in medicines, can be incorporated into ketone molecules using our approach via very mild conditions that tolerate various functional groups.
Enolizable Ketones as Activators of Palladium(II) Precatalysts in Amine Arylation Reactions
Hu, Huaiyuan,Gilliam, Ashley M.,Qu, Fengrui,Shaughnessy, Kevin H.
, p. 4127 - 4135 (2020/05/05)
Enolizable ketones have been identified as effective activators for palladium(II) precatalysts in the coupling of aryl bromides and aniline. N-arylation reactions catalyzed by [(DTBNpP)PdCl2]2 (DTBNpP = (bis(tert-butyl)neopentylphosphine) and PEPPSI-IPr precatalysts are activated by the addition of acetone, mesityl oxide, and 3-pentanone. 3-Pentanone was the most effective activator. Mechanistic studies show that acetone, 3-pentanone, and mesityl oxide reduce [(DTBNpP)PdCl2]2 in the presence of NaO-t-Bu to Pd0(DTBNpP)2
Blue Light Promoted Difluoroalkylation of Aryl Ketones: Synthesis of Quaternary Alkyl Difluorides and Tetrasubstituted Monofluoroalkenes
Li, Kangkui,Chen, Jingchao,Yang, Chunhui,Zhang, Keyang,Pan, Chunxiang,Fan, Baomin,Fan, Baomin
supporting information, p. 4261 - 4265 (2020/06/04)
A facile and cost-effective method for the preparation of fluoroalkylated compounds has been described by the direct photoexcitation of halofluoroalkanes with blue light absorptivity, enabling the difluoroalkylation of aryl ketones. The methodology has provided an efficient, mild, and catalyst-free synthetic method for quaternary difluoroalkylated arenes and tetrasubstituted monofluoroalkenes.
Allyl complexes for use in coupling reactions
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Page/Page column 38; 40, (2019/01/12)
A complex of formula (1), wherein, M is palladium or nickel, R1 and R2 are independently organic groups having 1-20 carbon atoms, or R1 and R2 are linked to form a ring structure with the phosphorus atom, R3 is selected from the group consisting of substituted and unsubstituted aryl, substituted and unsubstituted heteroaryl, and substituted and unsubstituted metallocenyl, R4 is an organic group having 1-20 carbon atoms, n is 0, 1, 2, 3, 4 or 5, X is an anionic ligand. A process for the preparation of the complex, and its use in carbon-carbon or carbon-nitrogen coupling reactions is also provided.
Palladate Precatalysts for the Formation of C-N and C-C Bonds
Zinser, Caroline M.,Warren, Katie G.,Nahra, Fady,Al-Majid, Abdullah,Barakat, Assem,Islam, Mohammad Shahidul,Nolan, Steven P.,Cazin, Catherine S. J.
, p. 2812 - 2817 (2019/08/12)
A series of imidazolium-based palladate precatalysts has been synthesized and the catalytic activity of these air- and moisture-stable complexes evaluated as a function of the nature of the imidazolium counterion. These precatalysts can be converted under
Ylide-Functionalized Phosphine (YPhos)-Palladium Catalysts: Selective Monoarylation of Alkyl Ketones with Aryl Chlorides
Hu, Xiao-Qiang,Lichte, Dominik,Rodstein, Ilja,Weber, Philip,Seitz, Ann-Katrin,Scherpf, Thorsten,Gessner, Viktoria H.,Goo?en, Lukas J.
supporting information, p. 7558 - 7562 (2019/10/02)
Ylide-functionalized phosphine (YPhos) ligands allow the palladium-catalyzed α-arylation of alkyl ketones with aryl chlorides with record setting activity. Using a cyclohexyl-substituted YPhos ligand, a wide range of challenging ketone substrates was efficiently and selectively monoarylated under mild conditions. A newly designed YPhos ligand bearing tert-butyl groups on the coordinating phosphorus atom is already active at room temperature. The synthetic potential was demonstrated by gram-scale reactions and the succinct synthesis of ?-caprolactone derivatives.
Cross-Coupling of Secondary Amides with Tertiary Amides: The Use of Tertiary Amides as Surrogates of Alkyl Carbanions for Ketone Synthesis
Wang, Shu-Ren,Huang, Pei-Qiang
, p. 887 - 891 (2019/07/18)
In recent years, exciting progress has been made in the field of direct transformation of amides, nevertheless, the condensation between two amides remains rare and restricted to homo-coupling reactions. Herein, we report the cross-coupling of secondary amides with tertiary amides, which provides a synthesis of ketones under mild conditions, and features the use of tertiary amides as surrogates of alkyl carbanions. The method relies on the coupling of enamines, generated from tertiary amides by catalytic partial reduction of tertiary amides with Vaska's catalyst, with nitrilium ions, formed in situ from secondary amides via activation with trifluoromethanesulfonic anhydride, and on the subsequent deformylation.
