66616-72-6Relevant academic research and scientific papers
Sterically enhanced 2-iminopyridylpalladium chlorides as recyclable ppm-palladium catalyst for Suzuki–Miyaura coupling in aqueous solution
Lin, Wenhua,Zhang, Liping,Ma, Yanping,Liang, Tongling,Sun, Wen-Hua
, (2021/10/20)
Sterically hindered 2-iminopyridine derivatives and their palladium chlorides complexes are designed and prepared, which efficiently promote the Suzuki–Miyaura coupling (SMC) reaction in aqueous solution. Besides the good to excellent yields and broad substrate scope, these catalysts can be reused for at least four new batches of the substrates. Spontaneous separation of coupling products in the aqueous reaction medium is the additional striking feature of this catalytic process. Furthermore, catalytic performance of palladium complexes bearing the azo-bridged phenyl groups was greatly influenced by the UV irradiation due to the cis/trans photoisomerization of azo unit of the catalysts. In conclusion, titled palladium complexes provide a green, sustainable, cost-effective, and convenient process to synthesize SMC products at multi-gram-scale reaction.
Agro-Waste Generated Pd/CAP-Ash Catalyzed Ligand-Free Approach for Suzuki–Miyaura Coupling Reaction
Patil, Rupesh C.,Jagdale, Ashutosh A.,Patil, Uttam P.,Ghodake, Jeevan S.,Mali, Sawanta S.,Hong, Chang K.,Patil, Suresh S.
supporting information, p. 3617 - 3631 (2021/04/02)
Abstract: We converted agro-waste Custard Apple Peels (CAP) to ash via thermal treatment, on which Pd(OAc)2 was immobilized easily that produced a low-cost, highly efficient Pd/CAP-ash catalyst. The prepared catalyst was fully characterized by using FT-IR, SEM, EDX, XRF, DSC-TGA, BET, HR-TEM, and XPS techniques. The Pd/CAP-ash catalyst was conveniently applied for the Suzuki–Miyaura coupling reaction under external base free and ligand-free conditions in an aqueous-organic solvent to produce biphenyls in good to excellent yields. The main attraction of our protocol an application of palladium-supported agro-waste material which is easily recoverable and recyclable provides mono and bis-coupled derivatives in a short reaction time. Graphic Abstract: [Figure not available: see fulltext.].
From the grafting of NHC-based Pd(II) complexes onto TiO2 to the in situ generation of Mott-Schottky heterojunctions: The boosting effect in the Suzuki-Miyaura reaction. Do the evolved Pd NPs act as reservoirs?
De Tovar, Jonathan,Rataboul, Franck,Djakovitch, Laurent
, p. 133 - 147 (2021/05/10)
The assumption that the real active species involved in the Suzuki-Miyaura reaction are homogeneous, heterogeneous or both is often proposed. However a lack of characterization of the true catalytic entities and their monitoring makes assumptions somewhat elusive. Here, with the aim of getting new insights into the formation of active species in the Suzuki-Miyaura reaction, a family of palladium(II) complexes bearing bis(NHC) ligands was synthesized for immobilization at the surface of TiO2. The studies reveal that once the complexes are anchored onto TiO2, the mechanism governing the catalytic reaction is different from that observed for the non-anchored complexes. All complexes evolved to Pd NPs at the surface of TiO2 under reaction conditions and released Pd species in the liquid phase. Also, this reactivity was boosted by the in situ generation of Mott-Schottky heterojunctions, opening new routes towards the design of heterogenized catalysts for their further implementation in reverse-flow reactors.
Synthesis of tetranuclear complex of Pd(II) with thiosemicarbazone ligands derived from 2-quinolone and its catalytic evaluation in Suzuki–Miyaura-type coupling reactions and alkoxylation of chloroquinolines
Nandhini, Sundar,Dharani, Sivadasan,Elamathi, Chennakrishnan,Dallemer, Frederic,Prabhakaran, Rathinasabapathi
, (2021/09/06)
A tetranuclear palladium(II) complex [(Pd(H-6MOQtsc-Ph))4] was obtained from the reaction between 6-methyl-2-oxo-1,2-dihydroquinoline-3-carboxaldehyde-4(N)-phenylthiosemicarbazone [H2-6MOQtsc-Ph] and K2[PdCl4]. The ligand and the Pd(II) complex were characterized by Fourier transform infrared spectroscopy (FT-IR), UV–visible and 1H NMR spectroscopy. X-ray diffraction studies confirmed the tetrameric nature of the complex with the coordination of ligand through quinolone carbonyl, azomethine nitrogen and thiolate sulfur atoms, and the fourth site is occupied by 2-quinolone nitrogen atom of the adjacent ligand. The synthesized complex was tested as catalyst in Suzuki–Miyaura coupling reaction between various chloroquinoline derivatives with phenylboronic acid. The reactions afforded unexpected C-alkoxylated (C-O coupling) products instead of more expected C-arylated (C-C coupling) products in the respective alcoholic mediums. However, the reactions with traditional aryl halides probed with very good yield of the corresponding C-C coupling products.
Synthesis of Enaminone-Pd(II) Complexes and Their Application in Catalysing Aqueous Suzuki-Miyaura Cross Coupling Reaction
Fu, Leiqing,Cao, Xiaoji,Wan, Jie-Ping,Liu, Yunyun
, p. 254 - 258 (2020/01/25)
A series of Pd(II)-enaminone complexes, termed Pd(eao)2, have been synthesized and characterized. The investigation on the catalytic activities of these new Pd(II)-reagents has proved that the Pd(eao)2-1 possesses excellent catalytic activity for the Suzuki- Miyaura cross coupling reactions of aryl bromides/chlorides with aryl/vinyl boronic acids in the environmentally benign media of aqueous PEG400 at low loading (5 mol‰). The superiority of this Pd(II)-reagent to those commercial Pd(II) and Pd(0) catalysts in catalyzing the reactions has been confirmed by parallel experiments. What's more, Pd(eao)2-2 has been found as a practical catalyst for the homo-coupling reactions of aryl boronic acids.
Ligand-free Suzuki coupling reaction with highly recyclable ionic palladium catalyst, Ti1-xPdxO2-x (x?=?0.03)
Bhat K, Shrikanth,Lanke, Veeranjaneyulu,Prasad, Jagadeesh Dasappa,Prabhu, Kandikere Ramaiah
, (2020/03/19)
We synthesized a recyclable palladium ionic catalyst, Ti0.97Pd0.03O1.97, using a solution combustion method (SCM), and characterized by XRD and Rietveld refinement. The synthesized Pd ionic catalyst is stable, insensitive to moisture and air, and easy to handle. The new catalyst has exhibited a phenomenal result for the Suzuki-Miyaura cross-coupling reaction with a broad substrate scope, and the reaction proceeds in an aqueous medium. The new catalyst proved beneficial and produced excellent yields irrespective of aryl halide used in the reaction (electron-rich or electron-poor or heterocyclic compounds) and shown a turnover frequency (TOF) of 14–25 h?1 for different reactions. The catalyst was coated on a cordierite monolith (Mg2Al4Si5O18), which enhanced the applicability of the catalyst, and made the handling and recycling of the catalyst very easy. Suzuki Miyaura reaction was carried out using both Pd-powder catalysts as well as the Pd-coated honeycomb, which gave almost similar results. We have demonstrated the recyclability of Pd coated cordierite monolith and shown the superiority of the catalyst over the other Pd catalysts for the Suzuki-Miyaura reaction.
Suzuki–Miyaura Cross-Coupling of Bromotryptophan Derivatives at Ambient Temperature
Dachwitz, Steffen,Duwe, Dario H.,Wang, Yating Hong,Gru?, Hendrik,Hannappel, Yvonne,Hellweg, Thomas,Sewald, Norbert
supporting information, p. 16357 - 16364 (2020/11/02)
Mild reaction conditions are highly desirable for bio-orthogonal side chain derivatizations of amino acids, peptides or proteins due to the sensitivity of these substrates. Transition metal catalysed cross-couplings such as Suzuki–Miyaura reactions are highly versatile, but usually require unfavourable reaction conditions, in particular, when applied with aryl bromides. Ligand-free solvent-stabilised Pd-nanoparticles represent an efficient and sustainable alternative to conventional phosphine-based catalysts, because the cross-coupling can be performed at considerably lower temperature. We report on the application of such a highly reactive heterogeneous catalyst for the Suzuki–Miyaura cross-coupling of brominated tryptophan derivatives. The solvent-stabilised Pd-nanoparticles are even more efficient than the literature-known ADHP-Pd precatalyst. Interestingly, the latter also leads to the formation of quasi-homogeneous Pd-nanoparticles as the catalytic species. One advantage of our approach is the compatibility with aqueous and aerobic conditions at near-ambient temperatures and short reaction times of only 2 h. The influence of different Nα-protecting groups, boronic acids as well as the impact of different amino acid side chains in bromotryptophan-containing peptides has been studied. Notably, a surprising acceleration of the catalysis was observed when palladium-coordinating side chains were present in proximal positions.
Concatenating Suzuki Arylation and Buchwald–Hartwig Amination by A Sequentially Pd-Catalyzed One-Pot Process—Consecutive Three-Component Synthesis of C,N-Diarylated Heterocycles
Mayer, Laura,Kohlbecher, Regina,Müller, Thomas J. J.
supporting information, p. 15130 - 15134 (2020/10/20)
The concatenation of Suzuki coupling and Buchwald-Hartwig amination in a consecutive multicomponent reaction opens a concise, modular and efficient one-pot approach to diversely functionalized heterocycles, as exemplified for 3,10-diaryl 10H-phenothiazines, 3,9-diaryl 9H-carbazoles, and 1,5-diaryl 1H-indoles, in high yields starting from simple staring materials. Moreover, this one-pot reaction is a sequentially palladium-catalyzed process that does not require additional catalyst loading after the first coupling step.
Palladium Supported on Silk Fibroin for Suzuki–Miyaura Cross-Coupling Reactions
Albano, Gianluigi,Farinola, Gianluca M.,Lo Presti, Marco,Milella, Antonella,Omenetto, Fiorenzo G.,Rizzo, Giorgio
supporting information, p. 6992 - 6996 (2020/11/30)
Silk fibroin supported Pd (Pd/SF) has been prepared and used as catalyst in Suzuki–Miyaura cross-coupling reactions in water/ethanol (4:1 v/v) mixture. The reactions proceed rapidly with aryl iodides and boronic acids with different electronic properties using low metal loading (0.38 mol-%). Pd/SF exhibits better recyclability compared to other biopolymer-supported Pd catalysts, up to nineteen cycles without loss of activity.
Visible-Light-Mediated N-Desulfonylation of N-Heterocycles Using a Heteroleptic Copper(I) Complex as a Photocatalyst
Hunter, Cameron J.,Boyd, Michael J.,May, Gregory D.,Fimognari, Robert
, p. 8732 - 8739 (2020/07/16)
A photoredox protocol that uses a heteroleptic Cu (I) complex, [Cu(dq)(BINAP)]BF4, has been developed for the photodeprotection of benzenesulfonyl-protected N-heterocycles. A range of substrates was examined, including indazoles, indoles, pyrazoles, and benzimidazole, featuring both electron-rich and electron-deficient substituents, giving good yields of the N-heterocycle products with broad functional group tolerance. This transformation was also found to be amenable to flow reaction conditions.
