Electron-rich Aromatic Compounds Research Articles

The functionalisation of electron rich aromatic compounds with 1,3-oxazolidines and 1,3-dimethylimidazolidine

N-Phenyl- and N-alkyl-oxazolidines react with alkyl chlorosilanes in the presence of electron rich aromatic compounds with the formation of the expected Mannich bases: 2-methoxycarbonyl-3-methyloxazolidine also reacts with 2-methylfuran in the presence of thionyl chloride to give an α-amino acid derivative: the iminium salt derived from 1,3-dimethylimidazolidine was also shown to react with 2-methylfuran.

The activation of aminals and aminol ethers by sulfur dioxide and their reactions with electron rich aromatic compounds

Reactions of bis(dialkylamino)methanes and ethoxydialkylaminomethanes with nucleophilic aromatic heterocycles in the presence of sulfur dioxide result in the formation of the expected Mannich bases in good yields. Reactions of phenols are similarly activated by sulfur dioxide which lead to improved regioselectivity: in particular the reactions of 2,5-dimethylphenol result in the formation of 2-dialkylaminomethyl-3,6-dimethylphenol whereas reaction occurs at the 4-position using the classical procedures.

Aminoalkylation of Electron-Rich Aromatic Compounds Using Performed Iminium Salts Derived from Aldehydes other than Formaldehyde

Aminoalkylation of Electron-Rich Aromatic Compounds Using Performed Iminium Salts Derived from Aldehydes other than Formaldehyde

Reaction of N,N-dimethylacrylamide/trifluoromethanesulfonic anhydride complex with electron-rich aromatic compounds

The reaction of N,N-dimethylacrylamide/trifluoromethanesulfonic anhydride complex with electron-rich aromatic compounds affords after hydrolysis the corresponding indanones and 1,3-diarylpropanones.

Phosphorus Crown-Ethers with Nitrogen-Containing Heterocycles

Abstract Phosphorus-containing crown-ethers functionalized by heterocycle fragments have essential advantages over the usual ones. The introduction of structural units of indoles, pyrroles and indolizines to phosphorus atom of the macrocyclic chain is capable to change lipophilic, complexing, biological and other properties of the initial crown-ethers. For synthesis of such compounds we have used dihalidophosphines obtained by direct substitution of the electron-rich aromatic compounds with phosphorus (III) halides. As a result, series of highly efficient macrocyclic compounds of a nowel type have been obtained.

The use of bis(aminol) ethers derived from aliphatic primary amines in the synthesis of secondary and tertiary amines

A series of bis(aminol) ethers were prepared from primary aliphatic amines and benzylamine together with formaldehyde and either ethanol or methanol; they were reacted with electrophiles to give N-alkyl- N-alkoxymethyl-methyleneiminium salts which gave mixtures of secondary and tertiary amines in reactions with electron rich aromatic compounds: sequential reactions with two different nucleophiles gave the expected tertiary amines.

New access to fluorinated glycolic acid derivatives from trifluoropyruvamides

Trifluoropyruvamide in their hydrates forms participate in various Friedel-Crafts type reactions with electron rich aromatic compounds. Good diastereoisomeric excess have been obtained starting from the chiral isobornylamine derivative.

Functionalization of Phenyl Rings by Imidoylnitrenes. 2. Cycloaddition or Electrophilic Aromatic Substititution?

The thermal decomposition of N‘-[(cyanoaryl)oxy]imidoyl azides with various substituted benzenes (OCH3, NHCOCH3, C(CH3)3, p-xylene, CH3, H, Cl, CO2CH3, NO2) has been studied in detail. With electron-rich aromatic nuclei, the addition of a nitrene yields a benzenonium ion (3) intermediate. Benzaziridine (1) and/or 3 intermediate is formed from benzene. Electron-poor aromatic nuclei generated only intermediate 1, in which no benzenonium diradical is formed. Intermediate 3 is stabilized by extended conjugation through an extra resonance structure. For electron-rich aromatic compounds at 65−120 °C, the thermodynamically-controlled products, N-arylisoureas ((Z)-NH-Ar), were produced in very high yield. Azepenes (the kinetically-controlled products) were detected by neither 1H-NMR nor a trapping experiment using tetracyanoethylene (TCNE). In the case of benzene 95% azepene was produced, which at 80 °C converted to isourea (k = 7.0 × 10-5 s-1). The ortho/para ratio resembles that of electrophilic aromatic substi...

The synthesis of 2-arylmethyltetrahydroisoquinolines from bis(aminol) ethers involving two iminium salt intermediates

The bis(aminol) ether derived from 3,4-dimethoxy-b-phenylethylamine, methanol, and formaldehyde reacts with trichloromethylsilane to afford an equilibrium mixture of N-chloromethyl-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline and its related iminium chloride. Interaction with electron rich aromatic compounds afford good yields of N-arylmethyl derivatives, including sendaverine methyl ether. Reactions of the bis(aminol) ether in the presence of the aromatic substrate allows the formation of the N-arylmethyl-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline derivatives in a one pot reaction.

Convenient preparation of difluoromethylene-functionalized compounds from chlorodifluoroacetic acid

A convenient route for the synthesis of difluoromethylene-functionalized compounds from chlorodifluoroacetic acid has been investigated. Bis(chlorodifluoroacetyl) peroxide, which was synthesized from chlorodifluoroacetic acid via its acid anhydride, was found to be a good reagent for the chlorodifluoromethylation of electron-rich aromatic compounds and olefins. The chlorine atom of the chlorodifluoromethylated compounds, thus prepared, exchanged hydrogen and allyl groups by reaction with tributyltin hydride and allyltributyltin, respectively, under radical conditions.

An Efficient Glycosylation Reaction of 1-Hydroxy Sugars with Various Nucleophiles Using A Catalytic Amount of Activator and Hexamethyldisiloxane

In the presence of hexamethyldisiloxane and anhydrous calcium sulfate, a catalytic amount of activator such as tin(II) trifluoromethanesulfonate, ytterbium trifluoromethanesulfonate , lanthanum trifluoromethanesulfonate or tin(II) chloride smoothly promotes the glycosylation reactions between 1-hydroxy sugars and free alcohols, electron-rich aromatic compounds or silylated nucleophiles to produce various O -, C - or N - glycosides stereoselectively in high yields. In the case of oxygen or nitrogen nucleophiles, β-ribosides are formed, except that α-ribosides are obtained predominantly in the presence of lithium perchlorate. In the case of carbon nucleophiles such as electron-rich aromatic compounds or silyl enol ethers derived from carbonyl compounds, perfect β-selectivity is shown either in the the presence or absence of lithium perchlorate. Further, pyranosyl substrates such as glucose or galactose afford the corresponding α-anomers, except with electron-rich aromatic compounds.

Cyclobis(paraquat-p-phenylene) as a synthetic receptor for electron-rich aromatic compounds: electrochemical and spectroscopic studies of neurotransmitter binding

The equilibrium binding constants of the charge-transfer complexes formed by the receptor cyclobis(paraquat-p-phenylene) with four neurotransmitters (dopamine, epinephrine, norepinephrine, and serotonin) and the related aromatic compounds indole and catechol were measured in aqueous media using a spectrophotometricmethod. The values obtained were in the range 1000-7500 M -1 . NMR studies confirmed that the surveyed π-donor guests are included inside the paraquat-lined cavity of the title receptor

Trifluoromethylation of aromatic compounds with sodium trifluoromethanesulfinate under oxidative conditions.

Radical trifluoromethylation occurs without Cu(II) but cations are involved with Cu(II). Electron-rich aromatic compounds are triluforomethylated with sodium trifluoromethanesulfinate and t-butyl hydroperoxide. Monotrifluoromethylation predominates in the presence of catalytic amounts of Cu(II) triflate whereas mono- and bis-trifluoromethylated aromatics are obtained in almost equal quantities in the absence of Cu(II).

Bis-trimethylsilylacetamide: A reagent for the control of Friedel-Crafts alkylation reactions using methyl chloromethoxyacetate

The Friedel-Crafts alkylation reactions of electron rich aromatic compounds using methyl α-chloro-α-methoxyacetate and Lewis acids leads predominantly to the formation of diarylacetic acid derivatives in which the second stage of the sequence is favoured by the presence of hydrogen chloride generated in the first step; effective control can be achieved in a number of cases by the addition of bis-trimethylsilylacetamide.

Reactivity of 3,6-dimethoxy-3,6-dimethylcyclohexa-1,4-diene (part 2). Regioselective arylation of electron-rich aromatic compounds

The reaction of 3,6-dimethoxy-3,6-dimethylcyclohexa-1,4-diene (1) with electron-rich heterocycles (furan, thiophene, pyrrole, 2-methyl-furan indole) and 1,3,5-trimethoxybenzene in the presence of catalytic amounts of zinc dichloride or concentrated sulftiric acid leads to the corresponding 2-aryl substituted p-xylenes 4 in good yields and in a regioselective manner.

ChemInform Abstract: A New Amino Protecting Group Readily Removable with Near Ultraviolet Light as an Application of Electron‐Transfer Photochemistry.

AbstractThe (methoxyaryl)alkylbenzenesulfonyl chlorides (I) react with the phenethylamine (II), producing the sulfonamides (III).

Reactions of trifluoromethyl bromide and related halides: part 10. Perfluoroalkylation of aromatic compounds induced by sulphur dioxide radical anion precursors

Perfluoroalkylation of electron-rich aromatic compounds with trifluoromethyl bromide, or long-chain perfluoroalkyl iodides, was performed in the presence of sodium dithionite or zinc–sulphur dioxide. This alkylation occurred at the ortho and para positions relative to the amino or hydroxy substituent. Pyrroles were perfluoroalkylated regioselectively at the 2-position. This alkylation was interpreted as a radical aromatic substitution; the formation of the perfluoroalkyl radical can be induced by a single-electron transfer from sulphur dioxide radical anion to the perfluoroalkyl halide.

Electrogenerated acid catalyzed acylation of electron-rich aromatics

The acylation of electron-rich aromatic compounds was achieved in good yields under very mild conditions using an electrogenerated acid catalyst. M(ClO 4) n dissolved in an organic anhydride (optionally mixed with a polar aprotic solvent) is useful for the electrochemical transformation in a divided cell.

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

AbstractThe 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.

Highly selective aromatic chlorination. Part 4. The chlorination of aromatic hydrocarbons with N-chloroamines in acidic solution

Benzene, toluene, some polymethylbenzenes, and naphthalene have been treated with N-chlorotrialkylammonium salts and N-chlorodialkylamines in trifluoroacetic acid at room temperature. With benzene, toluene, and 1,3,5-trimethylbenzene the major products arise from aromatic chlorination whereas with the other polymethylbenzenes side-chain reactions predominate. By controlling the acidity of the reaction and the nature of the N-chloroamine, the chlorination of toluene can be made to give preferentially 2- or 4-chlorination. However, the selectivities are not as great as reported previously with electron-rich aromatic compounds with a π-donor substituent. The products from the reaction of naphthalene are very dependent on the structure of the N-chlorinated amine. The bulky N-chlorotrialkylammonium salts selectively chlorinate the 1-position, but in low yield, whereas the less hindered N-chloropiperidine gives good yields of 1-(1-piperidino)naphthalene. The results from these studies are discussed in terms of arenium-ion and electron-transfer mechanisms.