Arene Chemistry Research Articles

ChemInform Abstract: Synthesis and Reactivity of Arenes Coordinated to Cyclopentadienyliron Cations

Abstract Over the past few decades, there has been tremendous interest in the chemistry of arenes coordinated to transition metal moieties due to their applications in the fields of organic and polymer synthesis. The electrophilicity of coordinated arenes allows for reactions with a number of carbon-, oxygen-, nitrogen- and sulfur-containing nucleophiles. This review describes the synthesis and reactivity of both mono- and polyiron arene complexes. Spectroscopic and electrochemical methods for the characterization of these coordination compounds are presented. The important synthetic applications of arene cyclopentadienyliron complexes are also described.

Mixed‐Metal (Platinum, Palladium), Mixed‐Pyrimidine (Uracil, Cytosine) Self‐Assembling Metallacalix[n]arenes: Dynamic Combinatorial Chemistry with Nucleobases and Metal Species

Reactions between the mononuclear mixed-nucleobase complex [Pt(en)(UH-N1)(CH2-N3)]+ (1; en: ethylenediamine; UH-N1: uracil monoanion bonded through the N1 atom; CH2-N3: neutral cytosine bonded through the N3 atom) and [Pd(II)(en)] or [Pd(II)(2,2'-bpy)] (2,2'-bpy: 2,2'-bipyridine) lead to libraries of compounds of different stoichiometries and different connectivities. In these compounds, the palladium entity binds to or cross-links either the N3 sites of uracil and/or the N1 sites of cytosine, following deprotonation of these positions to give uracil dianions (U) and cytosine monoanions (CH). Cyclic species, which can be considered as metallacalix[n]arenes, have been detected in several cases, with n being 4 and 8. The complexity of the compounds formed not only results from the possibility of the two different nucleobases in building block 1 engaging in different connectivities with the Pd entities, but also from the potential for the formation of oligomers of different sizes and different conformations; in the case of cyclic tetranuclear Pt(2)Pd(2) species, this can, in principle, lead to the various arrangements (cone, partial cone, 1,2-alternate, 1,3-alternate) known from calix[4]arene chemistry. A further complication arises from the fact that, depending on the mutual orientation of the exocyclic groups of the two nucleobases (O2 and O4 of uracil, O2 and N4 of cytosine), these sites can be engaged in additional chelation of [Pd(II)(en)] and [Pd(II)(2,2'-bpy)]. Thus, penta-, hexa-, and octanuclear complexes, Pt(2)Pd(3), Pt(2)Pd(4), and Pt(2)Pd(6), derived from cyclic Pt(2)Pd(2) tetramers have been isolated and characterized.

Arene Chemistry: From Historical Notes to the State of the Art

AbstractFor Abstract see ChemInform Abstract in Full Text.

Modern Arene Chemistry: Concepts, Synthesis and Applications. Edited by Didier Astruc

Modern Arene Chemistry: Concepts, Synthesis and Applications. Edited by Didier Astruc

Novel Substrates for Palladium‐Catalyzed Coupling Reactions of Arenes

AbstractFor Abstract see ChemInform Abstract in Full Text.

The Suzuki Reaction with Arylboron Compounds in Arene Chemistry

AbstractFor Abstract see ChemInform Abstract in Full Text.

Novel substrates for palladium-catalyzed coupling reactions of arenes.

Arenes and heteroarenes are ubiquitous substructures in biologically active agents and new materials. Thus, functionalization ("refinement") of simple arene precursors is still of major importance for preparative organic chemistry. During the last 20 years, especially transition-metal-catalyzed cross-coupling reactions of aryl halides and triflates have given arene chemistry new impetus. The first industrial applications were realized a few years ago. Quite recently, carbonic acid derivatives such as anhydrides and esters have added to the scope of substrates for these coupling reactions. Some recent developments in this area are presented in this Minireview.

Book Review: Modern Arene Chemistry. Edited by Didier Astruc

Book Review: Modern Arene Chemistry. Edited by Didier Astruc

The effect of solubility on the stability of titanium(IV) arene complexes derived from hexasubstituted arenes and TiCl 4

The investigation of new titanium(IV) hexaalkylarene complexes gave new insight into the stability of high-valent metal arene complexes. In contrast to low-valent transition metal arene complexes these complexes are in equilibrium with the free arenes. The stability of the complexes was shown to depend strongly on both the donor ability of the arene and on their solubility. This is unprecedented in transition metal arene chemistry.

Mixed-Ligand Arenechromium Carbonyl Complexes as Electronic Modulators

A number of mixed ligand η6 arenechromium carbonyl complexes have been prepared and investigated for their ability to effect electronic modulation of arene chemistry. In the case of an aniline-derived system, the arenechromium carbonyl complex is able to modulate the inductive capacity of the aniline nitrogen atom and thus, regulate its anchimeric ability. In the case of 8-phenylmenthol and benzyloxazolidinone derivatives, modulation of arene π basicity is achieved, and results suggest that important vinylarene π−π interactions exist in acrylate derivatives of these chiral auxiliary systems.

CATION-? INTERACTIONS IN CALIX[n]ARENE AND RELATED SYSTEMS

Non-covalent intermolecular forces have been recognized as a very important part of molecular interactions in complex biological systems. The fundamental functions of living matter such as transcription of genetic information in DNA, spatial arrangement of protein molecules, enzymatic functions or immunity system response are enabled owing to the presence of weak non-covalent forces based on hydrogen bonding interactions, van der Waals interactions, electrostatic interactions, hydrophobic effects, etc. Recently, among them so-called "cation–π" interactions have been proved to contribute to the overall binding process in various artificial or biological systems. Calix[n]arenes have emerged as an important family of molecules with promising applications in many branches of chemistry. Because of their suitable molecular preorganization with aromatic units being "concentrated' in a relatively small space, calix[n]arenes represent interesting compounds exhibiting an enhanced ability for cation–π interactions. The importance of such forces in calix[n]arene chemistry is demonstrated here on several recent examples. © 1997 John Wiley & Sons, Ltd.

ChemInform Abstract: New Findings in the Arene Chemistry of the 3d Transition Metals

ChemInformVolume 21, Issue 47 Reviews ChemInform Abstract: New Findings in the Arene Chemistry of the 3d Transition Metals K. JONAS, K. JONAS Max-Planck-Inst. f. Kohlenforsch., D-4330 Muelheim/RuhrSearch for more papers by this author K. JONAS, K. JONAS Max-Planck-Inst. f. Kohlenforsch., D-4330 Muelheim/RuhrSearch for more papers by this author First published: November 20, 1990 https://doi.org/10.1002/chin.199047292Read 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. Volume21, Issue47November 20, 1990 RelatedInformation

ChemInform Abstract: First Reactions of Dialkoxycarbenium Tetrafluoroborates with Pyrroles, 5H‐Dibenz(b,f)azepines, and Electron‐Rich Arenes.

Pyrrole (2a) and 2,5-dimethylpyrrole (2b) react with the dialkoxycarbenium tetrafluoroborates 1a-1c under kinetic control to yield the corresponding acylpyrrole derivatives. 5H-Dibenz[b,f]azepine (9a) and the 10,11-dihydro derivative 9b react only with the most electrophilic of the series of electrophiles tested, namely, diethoxycarbenium tetrafluoroborate (1a), to furnish the corresponding formyl derivatives. Similarly, in arene chemistry, the highly electron-rich N,N-dimethylaniline (13a) and 1,3,5-trimethoxybenzene (13b) are formylated by reaction with 1a.

New findings in the arene chemistry of the 3d transition metals

Abstract

First reactions of dialkoxycarbenium tetrafluoroborates with pyrroles, 5H‐dibenz[b,f]azepines, and electron‐rich arenes

AbstractPyrrole (2a) and 2,5‐dimethylpyrrole (2b) react with the dialkoxycarbenium tetrafluoroborates 1a‐1c under kinetic control to yield the corresponding acylpyrrole derivatives. 5H‐Dibenz[b,f]azepine (9a) and the 10,11‐dihydro derivative 9b react only with the most electrophilic of the series of electrophiles tested, namely, diethoxycarbenium tetrafluoroborate (1a), to furnish the corresponding formyl derivatives. Similarly, in arene chemistry, the highly electron‐rich N,N‐dimethylaniline (13a) and 1,3,5‐trimethoxybenzene (13b) are formylated by reaction with 1a.

ChemInform Abstract: Vapor‐Phase Chemistry of Arenes. Part 13. Reactivity and Selectivity in the Gas‐Phase Reactions of Hydroxyl Radicals with Monosubstituted Benzenes at 563 K.

AbstractThermolysis of (I) shows two product‐forming pathways: the major one leads to biaryls (III) which are accompanied by (IV) in some cases.

Vapour-phase chemistry of arenes. Part 13. Reactivity and selectivity in the gas-phase reactions of hydroxyl radicals with monosubstituted benzenes at 563 K

The reactions of hydroxyl radicals with benzene derivatives C6H5Z (Z = H, Me, F, Cl, Br, I, CF3, or CN) have been studied in a flow reactor at 563 K in nitrogen, using the thermolysis of ButOOH as a source of ˙OH. Under these conditions there are two product-forming pathways. The major one involves hydrogen abstraction to give aryl radicals ZC6H4˙(II) as the first step; depending on Z, its displacement to form phenol may also occur. Relative rates for hydrogen abstraction were determined in competition experiments using side-chain hydrogen abstraction from added toluene as a reference. This resulted in the order (for Z =): 1.8(Me), 1.0(H), 0.47(F), 0.29(Cl), 0.34(CF3), 0.20(CN), consonant with the electrophilic nature of ˙OH. The site selectivity of hydrogen abstractions was determined by scavenging part of the aryl radicals (II) with iodine. A Hammett plot, using σ constants for meta and para positions, led to ρ–1.0. The features of hydrogen abstraction by ˙OH are discussed and compared with those for the analogous reaction of Cl. The formation of phenol was found to decrease in importance in the order F, Cl, Br, and I. This result is rationalized on a thermochemical kinetic basis.

ChemInform Abstract: Vapour‐phase Chemistry of Arenes. Part 12. Reaction of Chlorobenzene and Derivatives with Hydroxyl Radicals at Approx. 290 °C. Hydroxy‐dechlorination.

AbstractThe action of hydroxyl radicals generated from tert. butyl hydroperoxide at 290°C on the title compounds (I) results in a hydroxy‐dechlorination to give the compounds (II) besides the formation of the arene‐derived products (II)‐(VI) and the compounds (VII) and (VIII), formed by displacement of CF; rather than Cl.

Vapour‐phase chemistry of arenes. Part XII. Reaction of chlorobenzene and derivatives with hydroxyl radicals at approx. 290°C. Hydroxy‐dechlorination

AbstractHydroxy‐dechlorination, \documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ {\rm ZC}_6 {\rm H}_4 {\rm Cl} + ^ \bullet{\rm OH}\xrightarrow{{(9)}}{\rm ZC}_6 {\rm H}_4 {\rm OH} + {\rm Cl}^ \bullet $\end{document} is advanced as a straightforward process enabling measurement of structural effects on rates of addition of \documentclass{article}\pagestyle{empty}\begin{document}$ ^ \bullet {\rm OH} $\end{document} to substituted benzenes. Hydroxyl radicals were generated from tert‐butyl hydroperoxide. Under the conditions employed (gas phase, 290°C), reaction (9) with chlorobenzene is 0.3 times as fast as H abstraction to give o/m/p‐\documentclass{article}\pagestyle{empty}\begin{document}$ {\rm ClC}_6 {\rm H}_4 ^ \bullet $\end{document} radicals. Analogous ipso substitution of methyl was not observed; with p‐chlorotoluene, \documentclass{article}\pagestyle{empty}\begin{document}$ ^ \bullet {\rm OH} $\end{document} forms \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm ClC}_6 {\rm H}_4 {\rm CH}_2 ^ \bullet $\end{document} at least 30 times faster than it gives reaction (9); with o‐ and p‐ClC6H4CF3 (2c), both reaction 9 and displacement of CF3 to give ClC6H4OH (reaction 12) occur, the latter ipso substitution being ca. 19 times faster with o‐ than with p‐2c. A thermokinetic rationale is given, for what is apparently a steric effect. Site selectivities for reaction (9), expressed as isomer distribution o/m/p, are: 55/25/20 for Z = Cl and 54/31/15 for Z = Me at 290°C.

Vapour-phase chemistry of arenes. Part 11. Autoxidation of chlorobenzene between 500–1 100 K. Mechanisms of formation of chlorophenols and phenol

Slow combustion of chlorobenzene (1) has been studied at low degrees of conversion (< 5%); mostly at atmospheric pressure, but at ca. 1 080 K under FVT-like conditions. Emphasis was on formation of the hydroxy derivatives o/m/p-ClC6H4OH (2) and the ipso substitution product phenol (3).A variety of ingredients, such as ButOOH, cyclohexane, nitroethane, and hydrogen peroxide, forming ˙OH in situ by thermolysis or autoxidation, has been used to induce the reaction of (1).The change in product composition (2, 3) with temperature revealed a major change in mechanism of hydroxylation between 600–700 K. Above ca. 600 K, H-abstraction (1)+˙OH→o/m/p-ClC6H4˙[accompanied by (1)+˙OH→Cl˙+(3)] is followed by rapid addition of O2(step 4) to give C6H4OO˙ radicals (v).At moderate temperatures (v) reacts bimolecularly, with itself or with HO2˙, leading to ClC6H4O˙(iv) and therefrom to (2). Thermokinetic analysis emphasises that at elevated temperatures (v) decomposes into (iv) and O(3P). The latter species adds to (1) and forms (2) rather efficiently, with an isomer distribution different from that associated with the pathway Ar˙→ArO2˙→ArOH.Data on model runs, including kinetic isotope effect measurements on p-DC6H4Cl and C6H6/C6D6, support our mechanistic interpretation.