气相芳香亲电取代反应研究进展

对气相芳香亲电取代反应的一般机理、小碎片正离子的亲电取代反应特性、反应中间体结构及质子在芳香环内和芳香环间的迁移反应作了评述。     

Phase-transfer catalysis in reactions of electrophilic aromatic substitution

Electrophilic substitution in aromatic compounds under conditions of phase-transfer catalysis is considered. Catalysts of phase transfer of electrophilic reagents are used; their efficiency and the mechanism of their action in organic solvent-water systems are discussed.This review is based on materials of the report delivered at the Conference Phase-Transfer Catalysis. New Ideas and Methods (March 1994).Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1895–1900, October, 1995.     

Crescent aromatic oligothioamides as highly selective receptors for copper(Ⅱ) ion

A series of crescent aromatic oligothioamides(4, 6, 8, 15, and 18) bearing different number of sulfur atoms were designed and synthesized via thionation of their corresponding aromatic oligoamides(3, 5, and 7) using Lawesson's reagent. The X-ray structure of a trimeric analogue(13) revealed the presence of intramolecular three-center hydrogen bonds that are responsible for the rigidification of the molecular backbone. The extraction by these novel receptors toward some representative heavy metal cations(Zn2+, Cd2+, Co2+, Ni2+, Pb2+, and Cu2+) and alkali and alkaline earth metal cations(Li+, Na+, K+, Rb+, Cs+, Ca2+, and Sr2+) demonstrated high efficiency(83.5%–96.4%) and superior selectivity for Cu2+ over other selected metal cations. Particularly, the extractability was correlated to both the number of sulfur atoms and orientation of thiocarbonyl groups as revealed in the order: 6 4 18 15. This is in stark contrast to the oligoamides that only gave much lower extractability(5.9%–16.4%), suggestive of the importance of replacement of carbonyl oxygen atoms with sulfur atoms in the extraction of Cu2+. The complexation behavior of 4, 6, and 8 with Cu2+ was also examined by UV-Vis and NMR techniques.     

Intramolecular electrophilic aromatic substitution in gas-phase-protonated difunctional compounds containing one or two arylmethyl groups

A variety of dibenzyl esters and ethers undergo a rearrangement process upon isobutane chemical ionization and collision-induced dissociation of their MH(+) ions, whereby a new bond is formed between the two benzyl groups, giving rise to abundant [C(14)H(13)](+) (m/z 181) ions. This rearrangement has been explained as an intramolecular electrophilic substitution in the gas phase occurring in an ion-neutral complex formed by the cleavage of one of the benzyl-oxygen bonds. A similar highly efficient intramolecular electrophilic substitution takes place in di-alpha- and beta-naphthylmethyl adipates affording m/z 281 [C(22)H(17)](+) ions, but not in the sterically hindered di-9-anthracylmethyl adipate. An analogous efficient rearrangement occurs in benzyl alpha- and beta-naphthylmethylcyclohexane-1,4-dicarboxylates and in benzyl alpha- and beta-phenylethylcyclohexane-1,4-dimethanol ethers. The analogous rearrangement is much less efficient in benzylallyl, benzylpropargyl and benzyl-9-anthracylmethyl derivatives, even less in benzylisopropyl and benzylacetyl analogs, and it is absent in benzyltetrahydropyranyl derivatives. The distinctive behavior of the protonated difunctional benzyl derivatives is interpreted in terms of the energy requirements of the O-R bond heterolysis of the protonated functionalities, the ability of the neutral R' groups (non-dissociated from the oxygen atom) to play the role of the nucleophile in the intramolecular electrophilic substitution processes and the electrophilicity of the R(+) ions.     

An MNDO study of the electrophilic aromatic substitution on trifluorobenzenes

Summary MNDO calculations of trifluorosubstituted benzenes and their protonated intermediates [Ph-F₃]H⁺ were performed. The results are discussed with respect to changes in geometry, charge distribution and stabilities of the individual intermediates. It appears that the predominant influence which controls the protonation position is the ability of the substituent F to increase both the positive charge and polarities of the carbon bonds situated in themeta-position with respect to the substituent, thus directing protonation to theortho- andpara-positions.     

Uncatalyzed polymerization of bistriazolinediones with electron-rich aromatic compounds via electrophilic aromatic substitution

The reaction of 4-substituted-1,2,4-triazoline-3,5-diones(4R-TD's), i.e., MeTD(4-methyl substituted) and PhTD(4-Phenyl substituted) with electron rich aromatic compounds were investigated. N,N-Dimethylaniline undergoes reaction instantaneously with MeTD and PhTD. Electrophilic aromatic substitution occurred at room temperature at the para position without use of any catalyst. N,N,N′,N′-tetramethyl-m-phenylenediamine (TMPDA) undergoes reaction with 2 mol of PhTD and MeTD which lead to the formation of 2:1 adducts in high yields. These compounds were fully characterized by IR, ¹³C-NMR, ¹H-NMR and elemental analysis and were used as model compounds. The reaction of bistriazolinediones with TMPDA was performed in dimethylformamid at room temperature. The reactions are exothermic, fast, and gave novel polymer structures via electrophilic aromatic substitution. Some physical properties and structural characterization of these new polymers have been studied, and will be reported.     

Nucleophilic aromatic substitution reactions of fluorobenzenechromium complexes with P-chiral secondary phosphine-boranes: synthesis of optically pure P-chiral (dialkyl)arylphosphine-boranes

Optically pure P-chiral (dialkyl)arylphosphine-boranes having high structural diversity were prepared by two- or three-component coupling of fluorobenzenechromium complexes, P-chiral secondary phosphine-boranes, and other nucleophiles. The stereochemical integrity at the P-stereogenic center was completely retained during the S_NAr process when the reaction was carried out in THF at low temperature.     

具有银-银相互作用的二(3-吡啶基)嘧啶-银(Ⅰ)配合物及其荧光性质

用分层法合成了两个配合物[Ag2(L)2](CF3COO)2(1)和[Ag2(L)2](CF3SO3)2(2)[L=2-甲基-4,6-二(3-吡啶基)嘧啶],并用元素分析、红外光谱、X-射线单晶衍射等手段对其进行了表征。晶体结构分析结果表明:具有双核大环结构的配合物1和2由Ag(Ⅰ)…Ag(Ⅰ)相互作用连接形成一维链状结构,并进一步通过π-π相互作用形成二维层状结构。研究了配合物2的荧光性质。     

The Direct Synthesis of Arylxenon Trifluoromethanesulfonates via electrophilic substitution

The reaction of xenonbis(trifluoroacetate) and trifluoromethanesulfonic acid (triflic acid) gave the new, highly reactive unsymmetrical xenon-oxo species CF₃COOXeOSO₂CF₃. Benzene derivates, containing electron withdrawing substituents such as -F, -CF₃, -Cl or -NO₂ were electrophilic attacked by this intermediate to yield arylxenon trifluoromethanesulfonates. Via this one-pot synthesis trifluoromethanesulfonates with the cations [Xe(2,4,6-F₃C₆H₂)]⁺, [Xe(2-F-5-NO₂C₆H₃)]⁺, [Xe(2-F-5-CF₃C₆H₃)]⁺ and [Xe(3,5-(CF₃)₂C₆H₃)]⁺ were prepared. All compounds were characterized by their NMR, mass, and vibrational spectra. Additionally, several new arylxenon trifluoromethanesulfonates were detected by ¹²⁹Xe-NMR spectroscopy as products of the reaction of 1,3-F₂C₆H₄ and further deactivated benzenes with xenontrifluoroacetate trifluoromethane sulfonate. Fluoro substituents in ortho position to xenon significantly increase the thermal stability of the arylxenon trifluoromethanesulfonates obtained. The molecular structure of [Xe(2,6-F₂C₆H₃)][OSO₂CF₃] was determined by single crystal diffraction methods. The arylxenon unit is weakly coordinated by one oxygen atom of the CF₃SO₃ anion. The salt crystallizes in the triclinic space group P1 , a = 880.9(3) pm, b = 1093.9(5) pm, c = 1209.8(5) pm, α = 89.04(4)°, β = 74.23(3)°, γ = 86.03(3)°, Z = 4.     

Reinvestigation of the noncatalyzed coupling of aryllithium with haloarene: a novel aromatic nucleophilic substitution pathway

Noncatalyzed coupling reactions of aryllithiums and haloarenes proceed not only through the well-known aryne route but also, in some cases, through a novel addition-elimination pathway. Indeed, ortho-chloro- and ortho-bromomethoxyarenes lead selectively to the corresponding ortho-biaryls through a chelation-driven aromatic nucleophilic substitution pathway. Contrary to common belief, such noncatalyzed coupling reactions often proceed with high regioselectivity and high yield. These results underline the potency of such simple reactions and open up a straightforward access to a wide range of biaryl structures; this also appears particularly useful for large-scale and biaryl building-block syntheses, as only cheap and readily available substrates are involved.     

The first nucleophilic aromatic substitution of suitably activated 2-methoxyfurans with Grignard reagents

The reaction of 2-methoxyfuroates 1 with Grignard reagents 2 leads to tertiary alcohols or S_NAr products depending on the position of the alkoxycarbonyl group. OMe-Displacement occurs only for 3-substituted derivatives. It takes place even for 3-acetyl-2-methoxyfuran while the presence of a further ester function at 4 position induces the formation of the sole 4-tertiary alcohol. The OMe-substitution has been verified for a wide range of furans and Grignard reagents and low yields have been found only in the reactions with the benzylic and allylic reagents which are delocalized anions. A mechanistic interpretation is given.     

Poly(arylene sulfide)s via nucleophilic aromatic substitution reactions of halogenated pyromellitic diimides

Nucleophilic aromatic substitution (SNAr) reactions are exploited to prepare poly(arylene sulfide)s (PAS's) via the reaction of bis-thiolates and dibrominated pyromellitic diimide (PMDI) derivatives. Small-molecule model studies reveal the reaction is well-defined and proceeds in quantitative yield in practical times at room temperature. Variation in comonomer feed ratios allowed some control over target polymer molecular weights in the step polymerization, but control was likely limited by the relatively poor polymer solubility in the dipolar aprotic solvents typically employed to promote SNAr reactions. One substitution pattern produces a steric “pocket” around the PMDI units, inducing a peculiar solubility trend in halogenated solvents; that is, greatly reduced solubility in CHCl₃ relative to CH₂Cl₂ and C₂H₂Cl₄. One example small-molecule readily dissolves in CHCl₃ at room temperature, then rapidly grows poorly soluble crystals revealed by single-crystal XRD to contain CHCl₃ molecules in the steric pockets. Finally, the recently demonstrated depolymerization of phthalonitrile-based PAS's via ipso substitution with monothiolates as chain scission agents yields quantitative molecular weight reduction to monomeric species from the polymers reported here.     

Syntheses of Binuclear Copper(I) Complexes Containing Benzimidazole

1 INTRODUCTION Procedures to synthesize copper(I) complexes are of great interest due to the diversity of products resulting from almost the same methodology. It has been long known that four-electron-donordipho- sphine compounds Ph2P(CH2)nPPh2 are excellent bi- dentate ligands[1, 2]. The chelating tendency of bis- (diphenylphosphino) methane is one of the dipho- sphine ligands most suitable to lock two metal atoms together in close proximity[3]. Many examples of bi- or polynuclear com…     

Nucleophilic aromatic substitution reactions of 1,2-dihydro-1,2-azaborine

Could go either way: The addition of nucleophiles to the parent 1,2-dihydro-1,2-azaborine and subsequent quenching with an electrophile generates novel substituted 1,2-azaborine derivatives. Mechanistic studies are consistent with two distinct nucleophilic aromatic substitution pathways depending on the nature of the nucleophile.     

Synthesis of 2-(4-amino substituted benzylidene) indanone analogues from aromatic nucleophilic substitution (SNAr) reaction

A novel, efficient and convenient procedure has been developed for the synthesis of 2-(4-amino-substituted benzylidene)indanone derivatives. In the first step, the reaction of 4-fluorobenzaldehyde with 5, 6-dimethoxy-2, 3-dihydro-1H-inden-1-one in the presence of NaOH in EtOH was described. In the next step, a variety of aliphatic and aromatic amines were reacted with 2-(4-fluorobenzylidene)-5, 6-dimethoxy-2, 3-dihydro-1H-Inden-1-one via aromatic substitution (S_NAr) reaction to produce 2-(4-aminobenzylidene)-5, 6-dimethoxy-2, 3-dihydro-1H-Inden-1-one derivatives as a novel class of 1-indanones. These products have been successfully prepared in good to excellent yields. ^1?H and ^13?C NMR, FT-IR spectroscopy and CHN analysis supported the proposed structures of the products.     

Synthesis of triarylamine‐containing poly(arylene ether)s by nucleophilic aromatic substitution reaction

We report synthesis of a series of new triarylamine‐containing AB‐type monomers and their polymers via nucleophilic aromatic substitution (S_NAr) reaction. Monomers consisting of a hydroxyl group at the para position of the nitrogen group in one phenyl ring and a fluorine leaving group at the para position in another phenyl ring were synthesized via palladium‐catalyzed amination reaction. The fluorine leaving group was activated by trifluoromethyl group at the ortho position and an electron‐withdrawing group (EWG) introduced at the para position of the unsubstituted phenyl ring that enabled control over monomer reactivity. S_NAr reaction of the monomers successfully produced corresponding poly(arylene ether)s with pendant EWGs that exhibited good solubility and thermal stability. Optical and electrochemical properties of the polymers were also affected by incorporation of EWGs. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2692‐2702     

Synthesis of 5-heteroarylazulenes: first selective electrophilic substitution at the 5-position of azulene

1,3-Di-tert-butylazulene reacted with highly electrophilic trifluoromethanesulfonate of N-containing heterocycles to give 5-(dihydroheteroaryl)azulene derivatives in good yield and treatment of the 5-(dihydroheteroaryl)azulene derivatives with KOH afforded 5-(heteroaryl)azulenes in excellent yield.     

Isocationic substitution of copper(II) complexes in anisotropic materials based on benzenetricarboxylate

A phase transfer isocationic substitution of lattice constituent macrocyclic complexes by copper(II) aqua complexes occurs upon the interaction of crystalline mono-and bis(macrocyclic) copper carboxylate complexes with acetonitrile solutions of copper(II) ammine complex. On the other hand, these materials do not react with cupric bis(ethylenediamine). __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 43, No. 2, pp. 124–129, March–April, 2007.     

Acid-catalyzed nucleophilic aromatic substitution: experimental and theoretical exploration of a multistep mechanism

The mechanism for the acid-mediated substitution of a phenolic hydroxyl group with a sulfur nucleophile has been investigated by a combination of experimental and theoretical methods. We conclude that the mechanism is distinctively different in nonpolar solvents (i.e., toluene) compared with polar solvents. The cationic mechanism, proposed for the reaction in polar solvents, is not feasible and the reaction instead proceeds through a multistep mechanism in which the acid (pTsOH) mediates the proton shuffling. From DFT calculations, we found a rate-determining transition state with protonation of the hydroxyl group to generate free water and a tight ion pair between a cationic protonated naphthalene species and a tosylate anion. Kinetic experiments support this mechanism and show that, at moderate concentrations, the reaction is first order with respect to 2-naphthol, n-propanethiol, and p-toluenesulfonic acid (pTsOH). Experimentally determined activation parameters are similar to the calculated values (Delta H exp not equal =105+/-9, Delta H calcd not equal =118 kJ mol(-1); Delta G exp not equal =112+/-18, Delta G calcd not equal =142 kJ mol(-1)).     

First example of aromatic electrophilic substitution using selenium(II) chloride

Russian Journal of Organic Chemistry -