Carbopalladation Reaction Research Articles

Access to Substituted Indenol Ethers via a Regioselective Intermolecular Carbopalladation Cascade.

Alkyne carbopalladation reactions can rapidly generate multiple new C-C bonds; however, regioselectivity is challenging for intermolecular variants. Using ynol ethers, we observe complete regiocontrol of migratory insertion followed by a second migratory insertion with a pendant alkene to turn-over the catalytic cycle. The resulting products are oligosubstituted 1-indenol ethers with defined stereochemistry based on the initial alkene geometry. Blocking β-hydride elimination allowed for C-H and C-C reductive elimination steps for catalyst turnover.

3 + 2 + 1] Pyridine Skeleton Synthesis Using Acetonitrile as C4N1 Units and Solvent.

The first [3 + 2 + 1] methodology for pyridine skeleton synthesis via cascade carbopalladation/cyclization of acetonitrile, arylboronic acids, and aldehydes was developed. This reaction proceeds via six step tandem reaction sequences involving the carbopalladation reaction of acetonitrile, a nucleophilic addition, a condensation, an intramolecular Michael addition, cyclization, and aromatization. Delightfully, both palladium acetate and supported palladium nanoparticles catalyzed this reaction with similar catalytic performance. The characterization results of the fresh and used supported palladium nanoparticle catalysts indicated that the reaction might be performed via a Pd(0)/Pd(II) catalytic cycle that began with Pd(0). Furthermore, the products showed good fluorescence characteristics. The green homogeneous/heterogenous catalytic methodologies pave a new way for constructing the pyridine skeleton.

Synthesis of [3.4]‐Spirooxindoles through Cascade Carbopalladation of Skipped Dienes

AbstractA synthetic route to [3.4]‐spirooxindoles based on cascade carbopalladation reactions of 1,4‐dienes is described. While carbopalladation of alkenes have been used to access mainly [4.4]‐ or [4.5]‐spirocycles, 4‐exo‐trig carbopalladation has not been yet applied to the synthesis of relevant [3.4]‐spirooxindole scaffolds bearing a cyclobutyl ring. In addition, the cascade reaction generates an exocyclic double bond that can serve as a platform to further diversify the substitution pattern of the spirooxindole nuclei.magnified image

Palladium-Catalyzed 4-Fold Domino Reaction for the Synthesis of a Polymeric Double Switch.

A palladium-catalyzed 4-fold domino reaction consisting of two carbopalladation reactions and two C-H activation reactions, followed by the introduction of an acrylate moiety, led to the tetra-substituted helical alkene A2, using the dialkyne A3 as a substrate. The alkene was copolymerized with butyl acrylate by using the reversible addition-fragmentation chain transfer polymerization (RAFT) to give the desired polymeric switch A1.

Conversion of Triple Bonds into Single Bonds in a Domino Carbopalladation with Norbornene.

A domino carbopalladation reaction of haloalkynes is presented. Remarkably, the four-time carbopalladation process converts the carbon-carbon triple bonds of haloalkynes stepwise into carbon-carbon double bonds, and finally to carbon-carbon single bonds. Features of this reaction are that the carbon-carbon double bonds of stable vinyl palladium intermediates are transformed into carbon-carbon single bonds with the generation of unstable alkyl palladium intermediates. The subsequently formed π-allylpalladium species are independently trapped by N-tosylhydrazones, boronic acids, and B2 pin2 in a highly diastereoselective manner, delivering the corresponding polycyclic and twisted products with a bicyclo[3.2.1]oct-2-en-3-yl)tricyclo[3.2.1.02,4 ]octane core skeleton in moderate to good yields via C-C and C-B bond formations. Significantly, the dual roles of norbornenes, ring construction and ring expansion, and the identification of electron-rich tri(2-furyl)phosphine as the ligand are found to be critical for the success of these transformations.

Oligoene-Based π-Helicenes or Dispiranes? Winding up Oligoyne Chains by a Multiple Carbopalladation/Stille/(Electrocyclization) Cascade.

A domino approach consisting of up to five consecutive steps to access either highly substituted dispiranes or π-helicenes from oligoyne chains is reported. The domino sequence consists of several carbopalladation reactions, a Stille cross-coupling to obtain the helicenes, and, depending on the steric demands of the helicene, a final 6π-electrocyclization to afford the dispiranes. Formally, the latter transformation contravenes the Woodward-Hoffmann rules, as revealed by X-ray crystallography of the dispirane. Additionally, the racemization barrier of the (Z,Z,Z)-triene-based helicene has been determined by a kinetic analysis and compared with results from density functional theory calculations. Characteristic points on the reaction coordinate were further analyzed according to their relaxed force constants (compliance constants).

Formal anti-carbopalladation reactions of non-activated alkynes: requirements, mechanistic insights, and applications.

Formal anti-carbopalladation reactions of CC triple bonds are uncommon, but highly useful transformations. Alkynes can be designed to give anti-carbopalladation products. Prerequisite is the exclusion of other reaction pathways to provoke the cis-trans isomerization of the syn-carbopalladation intermediate. Detailed mechanistic studies of this crucial step by experimental and computational means were performed. Application of an intramolecular version for the synthesis of oligocyclic compounds and substituted dibenzofurans is also described.

π-Helicenes truncated to a minimum: access through a domino approach involving multiple carbopalladations and a Stille coupling.

A novel type of π-helicenes is reported, in which the π-system is truncated to an all-s-cis all-Z oligoene chain. A domino sequence was developed, consisting of up to four consecutive carbopalladation reactions and a terminal Stille cross-coupling, to generate these entities in one step from the respective linear oligoynes. Despite the minimal π-system, very high optical rotation values were encountered for the single enantiomers. X-ray crystallography confirmed their screw-shaped structure.

ChemInform Abstract: Pentalenes with Novel Topologies: Exploiting the Cascade Carbopalladation Reaction Between Alkynes and gem‐Dibromoolefins.

ChemInformVolume 45, Issue 28 Isocyclic Compounds ChemInform Abstract: Pentalenes with Novel Topologies: Exploiting the Cascade Carbopalladation Reaction Between Alkynes and gem-Dibromoolefins. Gabor London, Gabor London Lab. Org. Chem., ETH Zuerich, CH-8093 Zuerich, Switz.Search for more papers by this authorMargarete von Wantoch Rekowski, Margarete von Wantoch Rekowski Lab. Org. Chem., ETH Zuerich, CH-8093 Zuerich, Switz.Search for more papers by this authorOliver Dumele, Oliver Dumele Lab. Org. Chem., ETH Zuerich, CH-8093 Zuerich, Switz.Search for more papers by this authorW. Bernd Schweizer, W. Bernd Schweizer Lab. Org. Chem., ETH Zuerich, CH-8093 Zuerich, Switz.Search for more papers by this authorJean-Paul Gisselbrecht, Jean-Paul Gisselbrecht Lab. Org. Chem., ETH Zuerich, CH-8093 Zuerich, Switz.Search for more papers by this authorCorinne Boudon, Corinne Boudon Lab. Org. Chem., ETH Zuerich, CH-8093 Zuerich, Switz.Search for more papers by this authorFrancois Diederich, Francois Diederich Lab. Org. Chem., ETH Zuerich, CH-8093 Zuerich, Switz.Search for more papers by this author Gabor London, Gabor London Lab. Org. Chem., ETH Zuerich, CH-8093 Zuerich, Switz.Search for more papers by this authorMargarete von Wantoch Rekowski, Margarete von Wantoch Rekowski Lab. Org. Chem., ETH Zuerich, CH-8093 Zuerich, Switz.Search for more papers by this authorOliver Dumele, Oliver Dumele Lab. Org. Chem., ETH Zuerich, CH-8093 Zuerich, Switz.Search for more papers by this authorW. Bernd Schweizer, W. Bernd Schweizer Lab. Org. Chem., ETH Zuerich, CH-8093 Zuerich, Switz.Search for more papers by this authorJean-Paul Gisselbrecht, Jean-Paul Gisselbrecht Lab. Org. Chem., ETH Zuerich, CH-8093 Zuerich, Switz.Search for more papers by this authorCorinne Boudon, Corinne Boudon Lab. Org. Chem., ETH Zuerich, CH-8093 Zuerich, Switz.Search for more papers by this authorFrancois Diederich, Francois Diederich Lab. Org. Chem., ETH Zuerich, CH-8093 Zuerich, Switz.Search for more papers by this author First published: 26 June 2014 https://doi.org/10.1002/chin.201428078Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume45, Issue28July 15, 2014 RelatedInformation

Pentalenes with novel topologies: exploiting the cascade carbopalladation reaction between alkynes and gem-dibromoolefins

A series of π-extended pentalenes with fused naphthyl-ring systems in different geometries were synthesised via a cascade carbopalladation reaction between alkynes and gem-dibromoolefins. This novel methodology was applied both in an intermolecular and an intramolecular fashion to access pentalenes with new topologies. The relationship between the fusion pattern and the opto-electronic properties within the synthesised series was investigated by UV/vis spectroscopy and electrochemical techniques. Novel pentalene reactivity, leading to yet unprecedented derivatives, was also uncovered.

A Domino Approach to Dibenzopentafulvalenes by Quadruple Carbopalladation

Four at one stroke: A quadruple domino carbopalladation reaction gives access to highly substituted dibenzopentafulvalenes and the complete pentafulvalene backbone is constructed in only one synthetic step. Structural and electronic properties have been evaluated by X-ray crystallography and cyclovoltammetry.

Flexible synthesis of anthracycline aglycone mimics via domino carbopalladation reactions

A synthesis of anthracycline aglycone derivatives is described. The key step utilizes a powerful domino carbopalladation approach and subsequent ring closure. During this process two of the four rings of the anthracycline scaffold are formed. Differently substituted carbohydrates and dialkyne chains serve as versatile and simple starting materials for the reaction sequence. Diverse building blocks lead to a variety of different products and a broad range of structural diversity.

Carbonyl Derivatives of Boradiazaindacene via Catalytic CO Insertion

A methodological study is presented dealing with carbopalladation reactions on BODIPY dyes bearing aryl-halogen functions. Using this technique, several ester and amide groups were efficiently introduced on the dyes. These changes do not affect the optical properties of the dyes and thus allow the construction of new BODIPY-based functional dyes with carboxylic anchoring groups or peptide links.

Palladium‐Catalyzed Carbocyclization of Alkynyl Ketones Proceeding through a Carbopalladation Pathway

Palladium‐Catalyzed Carbocyclization of Alkynyl Ketones Proceeding through a Carbopalladation Pathway

ChemInform Abstract: Cyclic Cascade Carbopalladation Reactions as a Route to Benzene and Fulvene Derivatives.

Abstract Palladium-catalyzed cyclization of appropriately structured triynes, haloalkenyldiynes, or haloalkenylalkyne-alkyne mixtures can provide the corresponding benzene derivatives, while the Pd-catalyzed intermolecular reaction of diynes with alkenyl halides can give fulvene derivatives.

Two Competing Mechanisms for the Copper-Free Sonogashira Cross-Coupling Reaction

The mechanism of the copper-free Sonogashira cross-coupling was investigated using a model reaction with differently para-substituted phenylacetylenes and 4-iodobenzotrifluoride as coupling partners and a Pd2(dba)3·CHCl3−AsPh3 catalyst system in methanol. A carbopalladation mechanism was ruled out through a series of experiments in which the equivalent of a carbopalladation reaction intermediate was synthesized by an alternate route, and its conversion to product was monitored. A Hammett correlation study revealed a possible mechanistic changeover when going from electron-rich to electron-poor alkynes in the model reaction. It is advocated that the reaction mechanism changes from a pathway involving a fast proton transfer from a slowly forming cationic Pd complex to a pathway involving a slow proton transfer from a neutral Pd complex on going from electron-rich to electron-poor alkynes. The amine base is believed to act as a base in both pathways and as a nucleophile promoting the formation of the cationi...

Palladium Complexes of N‐Heterocyclic Carbenes as Catalysts for Cross‐Coupling Reactions—A Synthetic Chemist's Perspective

Palladium-catalyzed C-C and C-N bond-forming reactions are among the most versatile and powerful synthetic methods. For the last 15 years, N-heterocyclic carbenes (NHCs) have enjoyed increasing popularity as ligands in Pd-mediated cross-coupling and related transformations because of their superior performance compared to the more traditional tertiary phosphanes. The strong sigma-electron-donating ability of NHCs renders oxidative insertion even in challenging substrates facile, while their steric bulk and particular topology is responsible for fast reductive elimination. The strong Pd-NHC bonds contribute to the high stability of the active species, even at low ligand/Pd ratios and high temperatures. With a number of commercially available, stable, user-friendly, and powerful NHC-Pd precatalysts, the goal of a universal cross-coupling catalyst is within reach. This Review discusses the basics of Pd-NHC chemistry to understand the peculiarities of these catalysts and then gives a critical discussion on their application in C-C and C-N cross-coupling as well as carbopalladation reactions.

Highly Stereoselective One‐Pot Synthesis of Tetrasubstituted Alkenes via Carbopalladation Reaction of Fluorine‐Containing Acetylene Derivatives.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Three‐Component Coupling of Benzyne: Domino Intermolecular Carbopalladation.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Palladium-Catalyzed Bicyclization Processes in the One Step Construction of Heteropolycyclic Ring Systems

This review concerns the preparation of heteropolycyclic systems in a single operation using palladium complexes and is restricted to methods where the palladium intervenes in at least two sequential different transformations. Keywords: intramolecular attack, palladium(II) complex, cyclization, Heck Reaction, Carbopalladation Reactions