Arene Alkene Research Articles

Elucidating ligand effects in rhodium(III)-catalyzed arene–alkene coupling reactions

Rhodium(III)-catalyzed CH couplings of arenes with alkenes are among the most powerful methods for CC bond formation. For these transformations, subtle manipulation of ancillary ligands can lead to dramatic changes in reactivity and selectivity. However, detailed mechanistic studies concerning the ligand effects are rare. In this study, we investigated the origin of ligand-controlled product-selectivity in rhodium(III)-catalyzed CH couplings of arenes with alkenes, using a series of well-defined [CpXRhIII] complexes that feature electronically or sterically distinct CpX (Cp (η5-C5H5), CpCF3 (η5-C5Me4CF3) and Cp* (η5-C5Me5)) ligands. A combination of experimental and theoretical investigations showed that (i) rhodium hydride species containing the electron rich Cp* ligand can undergo reinsertion of the alkene, thereby allowing rhodium-walking, (ii) rhodium hydride species involving the electron-deficient Cp or CpCF3 ligands prefer reductive elimination rather than alkene insertion. These findings offer valuable insights on future rational catalyst design for selective arene–alkene cross coupling reactions.

Pore-Directed Solid-State Selective Photoinduced E – Z Isomerization and Dimerization within Metal–Organic Frameworks

Pore-Directed Solid-State Selective Photoinduced <i>E</i> – <i>Z</i> Isomerization and Dimerization within Metal–Organic Frameworks

Arene-Alkene Cycloaddition.

Cycloadditions are among the most efficient chemical processes, combining atom economy, stereospecificity, and the ability to generate molecular complexity in a single step. Aromatic rings would in principle be ideal reaction partners, as they contain, at least from the topological point of view, both olefinic and diene subunits; however, the stability of the conjugated aromatic system would be broken by cycloaddition reactions, which are therefore rarely applied, because kinetics and thermodynamics hinder the process. From that aspect, photochemical activation opens interesting perspectives, as one can selectively provide excess energy to one of the reactants but not to the product, thus preventing thermal back reaction. Indeed, aromatic rings show a rich photochemistry, ranging from isomerizations, substitutions, and additions to cycloadditions. In this review, we will focus on cycloadditions, covering literature from early observations up to the present.

ChemInform Abstract: Iodine(III)‐Mediated Oxidative Intramolecular Arene—Alkene Coupling Exemplified in the Synthesis of Phenanthrenes.

ChemInform Abstract: Iodine(III)‐Mediated Oxidative Intramolecular Arene—Alkene Coupling Exemplified in the Synthesis of Phenanthrenes.

Alkyl–Aryl Coupling Catalyzed by Tandem Systems of Pincer-Ligated Iridium Complexes and Zeolites

We report that pincer-ligated iridium catalysts for alkane dehydrogenation can operate in tandem with zeolite catalysts for arene–alkene coupling, to effect the overall intramolecular dehydrocoupling of alkyl–H and aryl–H bonds (i.e., the dehydrocyclization of alkyl benzene). Thus, zeolite and soluble iridium cocatalysts in refluxing pentylbenzene (205 °C) gave high yields of 1-methyl-1,2,3,4-tetrahydronaphthalene. Subsequent dehydrogenation and isomerization affords 1- and 2-methylnaphthalene and 2-methyl-1,2,3,4-tetrahydronaphthalene. Total yields of cyclized product as high as 5.4 M (94%) have been obtained, corresponding to 6800 turnovers per mol Ir. Turnover numbers for the tandem-catalyzed dehydrocyclization are much greater than those obtained for simple dehydrogenation by Ir catalysts (to give olefins) in the absence of zeolite.

Iodine(iii)-mediated oxidative intramolecular arene–alkene coupling exemplified in the synthesis of phenanthrenes

A novel iodine(iii)-mediated synthesis of substituted phenanthrenes from ortho-vinylated biaryl derivatives through 6-endo-trig selective oxidative intramolecular arene–alkene coupling is reported.

DFT studies on the directing group dependent arene-alkene cross-couplings: arene activation vs. alkene activation.

Due to its green-chemistry advantages, the dehydrogenative Heck reaction (DHR) has experienced enormous growth over the past few decades. In this work, two competing reaction channels were comparatively studied for the Pd(OAc)2-catalyzed DHRs of arenes with alkenes, referred to herein as the arene activation mechanism and the alkene activation mechanism, respectively, which mainly differ in the involvement of the reactants in the C-H activation step. Our calculations reveal that the commonly accepted arene activation mechanism is plausible for the desired arene-alkene cross-coupling; in contrast, the alternative alkene activation mechanism is kinetically inaccessible for the desired cross-coupling, but it is feasible for the homo-coupling of alkenes. The nature of directing groups on reactants could mainly determine the dominance of the two competing reaction routes, and therefore, influence the experimental yields. A wide range of directing groups experimentally used are examined by the density functional theory (DFT) method in this work, providing theoretical guidance for screening compatible reactants.

ChemInform Abstract: Synthesis of Trisubstituted Alkenes via Direct Oxidative Arene—Alkene Coupling.

AbstractThe use of K2S2O8 in combination with Pd(OAc)2 as catalyst in a solvent mixture of AcOH and acetonitrile gives efficient access to trisubstituted alkenes.

Synthesis of Trisubstituted Alkenes via Direct Oxidative Arene–Alkene Coupling

The use of an inorganic oxidant with an acetic acid/acetonitrile solvent combination has been identified as optimal for direct arene/1,2-disubstituted alkene oxidative couplings, providing an efficient route to trisubstituted alkenes. The acetonitrile cosolvent dramatically accelerates the rate of reaction, and an insoluble inorganic oxidant limits unwanted oxidation of substrates. The scope of this procedure is illustrated with arenes and alkenes containing electron-donating and -withdrawing substituents resulting in a general synthetic strategy to trisubstituted alkenes. In situ ESI-MS analysis of the reaction components has identified the key Pd intermediates in the Fujiwara-Moritani catalytic cycle.

Microwave-assisted synthesis of 3-substituted indoles via intramolecular arene–alkene coupling of o-iodoanilino enamines

A generally applicable and high-yielding protocol for the synthesis of 3-substituted indole derivatives is described. Key features include microwave-assisted intramolecular arene–alkene coupling of o-iodoanilino enamines, and expedient synthesis of o-iodoanilino enamine substrates employing N,O-acetal TMS ethers, which could be conveniently derived from the corresponding amides. Our unique procedure seems quite efficient and provides an easy access to a variety of 3-substituted indoles as privileged structure for a wide range of biological targets.

ChemInform Abstract: Microwave‐Assisted Synthesis of 3‐Nitroindoles from N‐Aryl Enamines via Intramolecular Arene—Alkene Coupling.

A variety of N-aryl β-nitroenamines were effectively transformed into 3-nitroindoles in good yields and with complete regioselectivity via a rapid microwave (μW) assisted intramolecular arene–alkene coupling reaction. This report further demonstrates the versatility of this method by constructing 3-carboalkoxy- and 3-cyanoindoles. Optimization data, substrate scope, and applications are discussed.

The arene–alkene photocycloaddition

In the presence of an alkene, three different modes of photocycloaddition with benzene derivatives can occur; the [2 + 2] or ortho, the [3 + 2] or meta, and the [4 + 2] or para photocycloaddition. This short review aims to demonstrate the synthetic power of these photocycloadditions.

A Novel Intramolecular Arene—Alkene Photocycloaddition in 2‐Alkenyl Naphtha‐4‐chromanones — A Short Route to Functionalized Multicyclic Systems.

AbstractFor Abstract see ChemInform Abstract in Full Text.

A novel intramolecular arene–alkene photocycloaddition in 2-alkenyl naphtha-4-chromanones—a short route to functionalised multicyclic systems

On irradiation, 2-methyl-2-ethenyl naphtha-4-chromanone 1 undergoes an unusual intramolecular arene–alkene photocyclisation, followed by rearrangements to give a [5.3.1.0 6,1]benzotricycloundecene, 5 .

ChemInform Abstract: Asymmetric Arene—Alkene Cyclizations Mediated by a Chiral Organoselenium Reagent.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Access to Sterically Confined Nucleoside Analogues Via Intramolecular Photocycloadditions of Arene–Alkene Trichromophores

Biomedical ChromatographyVolume 11, Issue 2 p. 79-80 Extended Abstract Access to Sterically Confined Nucleoside Analogues Via Intramolecular Photocycloadditions of Arene–Alkene Trichromophores Wim Saeyens, Wim Saeyens University of Gent, Faculty of Pharmaceutical Sciences, Harelbekestraat 72, B-9000 Gent, BelgiumSearch for more papers by this authorDenis De Keukeleire, Corresponding Author Denis De Keukeleire University of Gent, Faculty of Pharmaceutical Sciences, Harelbekestraat 72, B-9000 Gent, BelgiumUniversity of Gent, Faculty of Pharmaceutical Sciences, Harelbekestraat 72, B-9000 Gent, BelgiumSearch for more papers by this authorPiet Herdewijn, Piet Herdewijn University of Gent, Faculty of Pharmaceutical Sciences, Harelbekestraat 72, B-9000 Gent, BelgiumSearch for more papers by this authorAndre De Bruyn, Andre De Bruyn University of Gent, Department of Organic Chemistry, Krijgslaan 281 (S-4), B-9000 Gent, BelgiumSearch for more papers by this author Wim Saeyens, Wim Saeyens University of Gent, Faculty of Pharmaceutical Sciences, Harelbekestraat 72, B-9000 Gent, BelgiumSearch for more papers by this authorDenis De Keukeleire, Corresponding Author Denis De Keukeleire University of Gent, Faculty of Pharmaceutical Sciences, Harelbekestraat 72, B-9000 Gent, BelgiumUniversity of Gent, Faculty of Pharmaceutical Sciences, Harelbekestraat 72, B-9000 Gent, BelgiumSearch for more papers by this authorPiet Herdewijn, Piet Herdewijn University of Gent, Faculty of Pharmaceutical Sciences, Harelbekestraat 72, B-9000 Gent, BelgiumSearch for more papers by this authorAndre De Bruyn, Andre De Bruyn University of Gent, Department of Organic Chemistry, Krijgslaan 281 (S-4), B-9000 Gent, BelgiumSearch for more papers by this author First published: 04 December 1998 https://doi.org/10.1002/(SICI)1099-0801(199703)11:2<79::AID-BMC644>3.0.CO;2-AAboutPDF 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. Volume11, Issue2March 1997Pages 79-80 RelatedInformation

Ion-Neutral Complexes of Protonated Alkylbenzenes: Experimental and Theoretical Studies

In the gas phase, the unimolecular reactions of metastable protonated alkyl arenes lead to alkyl cation formation with arene loss, protonated arene formation with alkene loss, and benzylic cation formation with alkane elimination. The dissociations are often preceded by an exchange between the hydrogen atoms of the chain and those of the ring, which can be rationalized by an interconversion between [arene alkyl cation] and [protonated arene alkene] ion-neutral complexes. By comparing the reactions of the metastable protonated alkyl arenes and those of their isomeric adducts (arene/alkyl cation) generated in the ion source by ionmolecule reaction, we show that n-complexes [arene alkyl cation] have a significant lifetime. By ab initio calculations, [C6H6 iso-C3H7+] and [C6H7+ C3H61 ion-neutral complexes are shown to be energy minima on the potential energy surface. They correspond therefore to stable structures. Two methods, namely, ab initio and semiempirical calculations, are used to calculate the interaction energies of [arene alkyl cation] complexes. The smallest stabilization energy (49 kJ/mol) corresponds to [C6H6 tert-CJ-b+] and the largest (65 kJ/mol) corresponds to [P-CH3Cd-I&H3 iso-C3H7+]. The [protonated arene alkene] complexes are less stabilized (ca. 25 kJ/mol). The calculations also indicate that [arene alkyl cation] complexes have n-structures, but do not correspond to electron donor-acceptor (EDA) systems since, among the components of their interaction energy, the charge exchange term is negligible. Finally, these results are used to propose energy diagrams and fragmentation pathways.

NMR study of complex triquinanes and bulleranes derived from photoisomerization of aryl‐substituted norbornan‐2‐ones

AbstractAnalysis of 1H and 13C NMR data by 2D NMR techniques was used for the structural identification of triquinanes and bulleranes considered as precursors of complex natural products such as (+)‐cerapicol. The polycyclic molecules are derived from a tandem Norrish Type I photoreaction and intramolecular arene–alkene meta photocycloaddition of aryl‐substituted norbornan‐2‐ones.

Tandem Norrish Type I reaction and intramolecular arene–alkene meta-photocycloaddition: novel photoisomerization of aryl-substituted norbornan-2-ones to triquinanes

Irradiation of the aryl-substituted norbornan-2-ones 6 and 7 at 254 nm furnishes the triquinanes 16 and 17(from 6) and 18(from 7)via tandem Norrish Type 1 reaction and intramolecular arene–alkene meta-photocycloaddition of the intermediate unsaturated lactols 12 and 13, respectively.

Concentration‐dependent deuterium isotope effects on the quantum yield of arene–alkene meta photocycloaddition: The role of excimers

AbstractA deuterium isotope effect on the arene–alkene meta photocycloaddition, reported earlier for toluene/toluene‐d8 photoaddition to cyclopentene, was found to depend on the concentration of both arene and alkene. This phenomenon is explained in terms of an unbalanced dissociation of ‘mixed’ excimers, which play a role in the intermolecular competition experiments.