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Palladium Catalysed Reaction

Milan Arambasic, Manjeet K Majhail, Robert N Straker, James D Neuhaus, Michael C Willis
This report concerns the development of an efficient Sonogashira-type coupling of arylmethylsulfides and terminal alkynes to generate aryl alkyne motifs. Orthogonal reactivity between traditional Pd catalysts, and the Rh catalysts employed, results in the ability to selectively activate either the C-S bond or C-X bond through catalyst choice. The Rh-bisphosphine catalyst has further been shown to be able to effect a hydroacylation-Sonogashira tandem sequence, and in combination with further onward reactions has been used in the synthesis of heterocycles and polycyclic systems...
February 14, 2019: Chemical Communications: Chem Comm
Gordon W Rewcastle, Swarna A Gamage, Julie A Spicer, Kit Y Tsang, Patrick D O'Connor, Jack U Flanagan, Woo-Jeong Lee, J M J Dickson, Peter R Shepherd, William A Denny
Using a scaffold-hopping approach, imidazo[1,2-a]pyridine analogues of the ZSTK474 (benzimidazole) class of phosphatidylinositol 3-kinase (PI3K) inhibitors have been synthesized for biological evaluation. Compounds were prepared using a heteroaryl Heck reaction procedure, involving the palladium-catalysed coupling of 2-(difluoro-methyl)imidazo[1,2-a]pyridines with chloro, iodo or trifluoromethane-sulfonyl-oxy (trifloxy) substituted 1,3,5-triazines or pyrimidines, with the iodo intermediates being preferred in terms of higher yields and milder reaction conditions...
February 3, 2019: Chemistry, An Asian Journal
Sanja Jeremic, Lidija Djokic, Vladimir Ajdačić, Nina Božinović, Vladimir Pavlovic, Dragan D Manojlović, Ramesh Babu, Ramsankar Senthamaraikannan, Orlando Rojas, Igor Opsenica, Jasmina Nikodinovic-Runic
Bacterial nanocellulose (BNC) emerged as an attractive advanced biomaterial that provides desirable properties such as high strength, lightweight, tailorable surface chemistry, hydrophilicity, and biodegradability. BNC was successfully obtained from a wide range of carbon sources including sugars derived from grass biomass using Komagataeibacter medellinensis ID13488 strain with yields up to 6 g L-1 in static fermentation. Produced BNC was utilized in straightforward catalyst preparation as a solid support for two different transition metals, palladium and copper with metal loading of 20 and 3 wt%, respectively...
January 30, 2019: International Journal of Biological Macromolecules
Vera L M Silva, Artur M S Silva
Palladium-catalysed reactions have had a large impact on synthetic organic chemistry and have found many applications in target-oriented synthesis. Their widespread use in organic synthesis is due to the mild conditions associated with the reactions together with their tolerance of a wide range of functional groups. Moreover, these types of reactions allow the rapid construction of complex molecules through multiple bond-forming reactions in a single step, the so-called tandem processes. Pd-catalysed reactions have been applied to the synthesis of a large number of natural products and bioactive compounds, some of them of complex molecular structures...
January 9, 2019: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Alexander Fawcett, Tobias Biberger, Varinder K Aggarwal
Transition-metal-catalysed cross-coupling reactions, particularly those mediated by palladium, are some of the most broadly used chemical transformations. The fundamental reaction steps of such cross-couplings typically include oxidative addition, transmetallation, carbopalladation of a π-bond and/or reductive elimination. Herein, we describe an unprecedented fundamental reaction step: a C-C σ-bond carbopalladation. Specifically, an aryl palladium(II) complex interacts with a σ-bond of a strained bicyclo[1...
December 10, 2018: Nature Chemistry
Giuseppe Dilauro, Andrea Francesca Quivelli, Paola Vitale, Vito Capriati, Filippo Perna
Direct palladium-catalysed cross-couplings between organolithiums and (hetero)aryl halides (Br, Cl) proceed fast, cleanly and selectively at room temperature in air, with water as the only reaction medium and in the presence of NaCl as a cheap additive. Under optimised reaction conditions, a water-accelerated catalysis is responsible for furnishing Csp3-Csp2, Csp2-Csp2, and Csp-Csp2 cross-coupled products, competitively with protonolysis, within a 20 s reaction time, in yields of up to 99%, and in the absence of undesired dehalogenated/homocoupling side-products even if it starts from challenging secondary organolithiums...
December 5, 2018: Angewandte Chemie
W Rush Scaggs, Toya D Scaggs, Thomas N Snaddon
Herein we describe the direct enantioselective Lewis base/Pd catalysed α-allylation of pyrrole acetic acid esters. This provides high isolated yields of highly enantioenriched products and exhibits broad reaction scope with respect to both reaction partners. The products can be readily elaborated in a manner which points towards potential applications in target directed synthesis.
November 28, 2018: Organic & Biomolecular Chemistry
Martin Gazvoda, Miha Virant, Balazs Pinter, Janez Košmrlj
The seminal contributions by Sonogashira, Cassar and Heck in mid 1970s on Pd/Cu- and Pd-catalysed (copper-free) coupling of acetylenes with aryl or vinyl halides have evolved in myriad applications. Despite the enormous success both in academia and in industry, however, critical mechanistic questions of this cross-coupling process remain unresolved. In this study, experimental evidence and computational support is provided for the mechanism of copper-free Sonogashira cross-coupling reaction. In contrast to the consensus monometallic mechanism, the revealed pathway proceeds through a tandem Pd/Pd cycle linked via a multistep transmetallation process...
November 16, 2018: Nature Communications
Christian A Malapit, James R Bour, Conor E Brigham, Melanie S Sanford
The Suzuki-Miyaura cross-coupling of organoboron nucleophiles with aryl halide electrophiles is one of the most widely used carbon-carbon bond-forming reactions in organic and medicinal chemistry1,2 . A key challenge associated with these transformations is that they generally require the addition of an exogenous base, the role of which is to enable transmetallation between the organoboron nucleophile and the metal catalyst3 . This requirement limits the substrate scope of the reaction because the added base promotes competitive decomposition of many organoboron substrates3-5 ...
November 2018: Nature
Leleti Rajender Reddy, Sharadsrikar Kotturi, Yogesh Waman, Vudem Ravinder Reddy, Chirag Patel, Ajinath Kobarne, Sasikumar Kuttappan
A highly efficient method of visible light mediated Ni(II)-catalyzed photoredox N-arylation of Cbz-amines/Boc-amines with aryl electrophiles at room temperature is reported. The methodology provides a common access to a wide variety of N-aromatic and N-heteroaromatic carbamate products that find use in the synthesis of several biologically active molecules and provides a distinct advantage over traditional palladium-catalyzed Buchwald reaction.
October 18, 2018: Journal of Organic Chemistry
Julien Pedron, Clotilde Boudot, Sandra Bourgeade-Delmas, Alix Sournia-Saquet, Lucie Paloque, Maryam Rastegari, Mansour Abdoulaye, Hussein El-Kashef, Colin Bonduelle, Geneviève Pratviel, Susan Wyllie, Alan H Fairlamb, Bertrand Courtioux, Pierre Verhaeghe, Alexis Valentin
An antikinetoplastid pharmacomodulation study at position 3 of the recently described hit molecule 3-bromo-8-nitroquinolin-2(1H)-one was conducted. Twenty-four derivatives were synthesised using the Suzuki-Miyaura cross-coupling reaction and evaluated in vitro on both Leishmania infantum axenic amastigotes and Trypanosoma brucei brucei trypomastigotes. Introduction of a para-carboxyphenyl group at position 3 of the scaffold led to the selective antitrypanosomal hit molecule 3-(4-carboxyphenyl)-8-nitroquinolin-2(1H)-one (21) with a lower reduction potential (-0...
September 17, 2018: ChemMedChem
Raysa Khan, Sarote Boonseng, Paul D Kemmitt, Robert Felix, Simon J Coles, Graham J Tizzard, Gareth Williams, Olivia Simmonds, Jessica-Lily Harvey, John Atack, Hazel Cox, John Spencer
5-Phenyl-1,3-dihydro- 2H -1,4-benzodiazepin-2-ones react under palladium- and visible light photoredox catalysis, in refluxing methanol, with aryldiazonium salts to afford the respective 5-(2-arylphenyl) analogues. With 2- or 4-fluorobenzenediazonium derivatives, both fluoroaryl- and methoxyaryl- products were obtained, the latter resulting from a SN Ar on the fluorobenzenediazonium salt ("nuisance effect"). A computational DFT analysis of the palladium-catalysed and the palladium/ruthenium-photocalysed mechanism for the functionalization of benzodiazepines indicated that, in the presence of the photocatalyst, the reaction proceeds via a low-energy SET pathway avoiding the high-energy oxidative addition step in the palladium-only catalysed reaction pathway...
September 18, 2017: Advanced Synthesis & Catalysis
Philani P Mpungose, Zanele P Vundla, Glenn E M Maguire, Holger B Friedrich
In the last 30 years, C⁻C cross coupling reactions have become a reliable technique in organic synthesis due their versatility and efficiency. While drawbacks have been experienced on an industrial scale with the use of homogenous systems, many attempts have been made to facilitate a heterogeneous renaissance. Thus, this review gives an overview of the current status of the use of heterogeneous catalysts particularly in Suzuki and Heck reactions. Most recent developments focus on palladium immobilised or supported on various classes of supports, thus this review highlights and discuss contributions of the last decade...
July 10, 2018: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Francesco Messa, Serena Perrone, Martina Capua, Francesco Tolomeo, Luigino Troisi, Vito Capriati, Antonio Salomone
A palladium-catalysed aminocarbonylation of (hetero)aryl iodides has, for the first time, been accomplished in deep eutectic solvents as environmentally benign and recyclable media, under mild conditions. The reactions proceeded with a good substrate scope, and a variety of amides have been synthesized in yields up to 98%.
July 17, 2018: Chemical Communications: Chem Comm
Zupeng Chen, Evgeniya Vorobyeva, Sharon Mitchell, Edvin Fako, Manuel A Ortuño, Núria López, Sean M Collins, Paul A Midgley, Sylvia Richard, Gianvito Vilé, Javier Pérez-Ramírez
Palladium-catalysed cross-coupling reactions, central tools in fine-chemical synthesis, predominantly employ soluble metal complexes despite recognized challenges with product purification and catalyst reusability1-3 . Attempts to tether these homogeneous catalysts on insoluble carriers have been thwarted by suboptimal stability, which leads to a progressively worsening performance due to metal leaching or clustering4 . The alternative application of supported Pd nanoparticles has faced limitations because of insufficient activity under the mild conditions required to avoid thermal degradation of the substrates or products...
August 2018: Nature Nanotechnology
Mayukh Deb, Susanta Hazra, Ajay Gupta, Anil J Elias
A palladium catalysed methodology for mono-selective oxidative aroylation of ferrocene has been achieved. 10 mol% of Pd(OAc)2 was used as the catalyst for this radical aroylation reaction using O-methyl-oxime as the directing group. tert-Butyl hydroperoxide was used as an oxidant and both aldehydes and alcohols were used as acyl-equivalents. The protocol has been extended to aryl, heteroaryl and sterically hindered aroylating agents. Acidic-hydrolysis with 6(N) HCl of the directing group resulted in unsymmetrically substituted ketone derivatives of ferrocene, which have not been achieved otherwise...
May 29, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Hirokazu Tsukamoto, Kazuya Ito, Takayuki Doi
Multi-substituted dihydrofurans were obtained from a palladium-catalysed coupling reaction between 2,3-alkadienols and ketones bearing an electron-withdrawing group at the α-position. Methanol as a solvent was essential for the initial dehydrative substitution to suppress the competitive hydroalkylation of the diene moiety. The substitution would be followed by intramolecular hydroalkoxylation under the same catalysis.
May 15, 2018: Chemical Communications: Chem Comm
Bowen Lei, Xiaojiao Wang, Lifang Ma, Yan Li, Ziyuan Li
An iron-catalysed intermolecular vicinal aminoazidation of alkenes, using N-fluorobenzenesulfonimide (NFSI) and trimethylsilyl azide (TMSN3) as the imidating and azidating reagents, respectively, is described, which could potentially provide a valuable route toward diverse vicinal diamine derivatives of great significance in medicinal chemistry and organic synthesis. Such iron-catalysed aminative bisfunctionalization of alkenes with NFSI has not been reported yet. Comparing to previously employed copper or palladium catalysts, the iron catalyst, FeCl2, was demonstrated to be a good alternative for its comparable efficiency and broad alkene scope...
May 2, 2018: Organic & Biomolecular Chemistry
Xuekai Zhang, Gang Lu, Meng Sun, Madhu Mahankali, Yanfei Ma, Mingming Zhang, Wangde Hua, Yuting Hu, Qingbing Wang, Jinghuo Chen, Gang He, Xiangbing Qi, Weijun Shen, Peng Liu, Gong Chen
New methods capable of effecting cyclization, and forming novel three-dimensional structures while maintaining favourable physicochemical properties are needed to facilitate the development of cyclic peptide-based drugs that can engage challenging biological targets, such as protein-protein interactions. Here, we report a highly efficient and generally applicable strategy for constructing new types of peptide macrocycles using palladium-catalysed intramolecular C(sp3 )-H arylation reactions. Easily accessible linear peptide precursors of simple and versatile design can be selectively cyclized at the side chains of either aromatic or modified non-aromatic amino acid units to form various cyclophane-braced peptide cycles...
May 2018: Nature Chemistry
Anna Isakova, Billy J Murdoch, Katarina Novakovic
The oscillatory palladium-catalysed carbonylation reaction opens new horizons for applications in smart materials due to the versatility of its conditions and substrates, as well as the adjustability of amplitude and period of pH oscillations. A variety of viable substrates have been demonstrated, including polymeric alkyne-terminated substrates. However, so far, there have not been any reports of polymer-based palladium catalysts in oscillatory mode. In this paper, we demonstrate pH oscillations in various systems, using commercially available palladium acetate, a triphenylphosphine palladium acetate complex and a polymer-bound palladium catalyst...
April 4, 2018: Physical Chemistry Chemical Physics: PCCP
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