Iron-catalyzed cascade reaction of ynone with o-aminoaryl compounds: a Michael addition-cyclization approach to 3-carbonyl quinolines

An efficient iron-catalyzed cascade Michael addition-cyclization of o-aminoaryl compounds including o-aminoaryl aldehydes, o-aminoaryl ketones, and o-aminobenzyl alcohols with ynones for the synthesis of 3-carbonyl quinolines is reported. The reactions proceed to afford 3-carbonyl quinoline derivatives with or without substituent at the C-4 position in good to high yields using Iron(III) chloride hexahydrate as the catalyst in the air.     

Photo-Fries rearrangement of N-arylsulfonamides to aminoaryl sulfone derivatives

Photochemical reaction of variously substituted p-toluenesulfonanilides was studied. The reaction gives rearranged products, o- and p-amino-substituted diaryl sulfones with the combined yields of 38-72%: the p-isomer is more favored over the o-isomer with the selectivity ratio of 1.1-4.3 depending on the substituents. N-Alkylation of the sulfonanilides increases the yields of the rearranged products, and e-withdrawing substituents on the N-phenyl ring does not lower the yields drastically. This study provides simple methodology for the synthesis of o- and p-aminoaryl sulfones which are otherwise not easily accessible.     

Synthesis and characterization of oxadisilole-fused acridines,dioxatrisilole-fused acridines and benzo[b]acridines

Oxadisilole-fused acridines, dioxatrisilole-fused acridines and benzo[b]acridines were synthesized through nucleophilic additions and aromatization reactions of arynes with 2-aminoaryl ketones or 2-aminoaryl aldehydes in good yields at room temperature. The photophysical, redox and thermal properties of these compounds were characterized. These compounds show potential applications as strong deep-blue or green emitters for OLED because of high fluorescence quantum yields and good thermal stabilities.     

Synthesis and electron impact mass spectra of 3-substituted 2-acylaminoindazoles

3-Substituted-2-acylaminoindazoles 2 were prepared via oxidative cyclization of o-aminoaryl ketone acylhydrazones 1 with iodosobenzene diacetate. Their electron ionization mass spectra were recorded and in addition to the molecular ions show common fragmentation pathways corresponding to the [M-N₂]⁺, [M-NHCOX]⁺ and [M-COX]⁺ ions, with some influence on the skeletal fragmentation by different substituents.     

Reaction of vanadocene and vanadocene dichloride with ortho-iodobenzoic acid

At the interaction of bis (η⁵-cyclopentadienyl)vanadium with iodobenzoic acid or trimethylsilyl o-iodobenzoate in toluene depending on the ratio of the initial reagents bis(η⁵-cyclopentadienyl)vanadium(o-iodobenzoate) or η⁵-cyclopentadienylvanadium-bis-o-iodobenzoate were obtained in high yields. The latter was also formed in the reaction of bis(η⁵-cyclopentadiene)vanadium dihloride with trimethylsilyl o-iodobenzoate.     

An iodoacetamide-based free radical cyclisation approach to the 7,12-dihydro-indolo[3,2-d][1]benzazepin-6(5H)-one (paullone) system

A potentially versatile route to 2-(2-aminoaryl)indoles is described based on a palladium-mediated cyclisation of N-substituted indoles, together with free radical cyclisation of their N-benzyliodoacetamide derivatives to the 7,12-dihydro-indolo[3,2-d][1]benzazepin-6(5H)-one system.     

Facile synthesis of isoquinolines by imination and subsequent palladacycle-catalyzed iminoannulation of internal alkynes

An efficient and facile synthesis of isoquinolines has been described via a tandem reaction of imination of o-halobenzaldehydes with tert-butyl amine and subsequent palladacycle-catalyzed iminoannulation of internal alkynes. This tandem reaction could be carried out successively in one pot without any special operation, and the annulation step could afford isoquinolines derivatives in moderate to good yields with high regioselectivity. In addition, the simple synthesis of indoles was realized by palladacycle-catalyzed annulation of o-iodoaniline or o-bromoanilines with internal alkynes.     

Silica sulfuric acid as an efficient catalyst for the Friedländer quinoline synthesis from simple ketones and ortho-aminoaryl ketones under microwave irradiation

The synthesis of quinoline derivatives via Friedländer method from ortho-aminoaryl ketones in the presence of a catalytic amount of silica sulfuric acid (SSA) under solvent-free condition and microwave irradiation was described. A good range of simple ketones such as cyclohexanone and deoxybenzoin were used.     

Protection of stainless steel by the electrodeposition of polyaniline/poly(o-phenylenediamine) composite layers

Three polyaniline (PANI)/poly(o-phenylenediamine) (PoPD) mixtures have been electrochemically deposited on a stainless steel surface from an acidic solution. Electrocopolymerization was favorable at high molar ratios of aniline to o-phenylenediamine, and the resulting copolymer is a random type. Two bilayers, PoPD/PANI and PANI/PoPD, were prepared by successive electrodeposition, during which different multiphase structures were obtained. The presence of PoPD with PANI in the copolymer or multilayer structures enhances the passivation of the SS. The bi-layer coating in which a PANI layer lies under the PoPD produced the best passive oxide on the SS. The resistance to pitting increases with the coating order as follows: PANI < copolymer ? PANI/PoPD < PoPD < PoPD/PANI.     

Tungstate sulfuric acid as an efficient catalyst for the synthesis of benzoxazoles and benzothiazoles under solvent-free conditions

Tungstate sulfuric acid (TSA) has been found to be an efficient and reusable catalyst for the synthesis of benzoxazole and benzothiazole derivatives via reactions of orthoesters with o-aminophenols or o-aminothiophenols in high yields.     

Catalytic fluorination of 1,3-dicarbonyl compounds using iodoarene catalysts

Catalytic fluorination of 1,3-dicarbonyl compounds with aqueous hydrofluoric acid proceeded efficiently with the aid of iodoarene catalysts in the presence of m-CPBA as a terminal oxidant. o-Iodotoluene, o-iodoanisole, and o-ethyliodobenzene showed a high catalytic efficiency to give 2-fluoro-1,3-dicarbonyl compounds in good yields.     

Chelating behavior of new chelating resins derived from n-(o-hydroxybenzyl)iminodiacetic acid

The chelating behavior of a new resin prepared by polycondensation of N-(o-hydroxybenzyl) iminodiacetic acid (o-HDA) with phenol and formaldehyde, is compared with that of the monomer, with p-HDA resin and p-HDA monomer, and with Chelex-100. The order of chelate stability for the o-HDA resin is Cu(II) > Ni(II) > Zn(II) > Co(II). An unusually high stability of the o-HDA and o-HDA resin iron(III) chelates in acidic solution is attributed to the participation of the o-hydroxyl group in the coordination process.     

Poly(N-bromo-N-ethylbenzene-1,3-disulfonamide) and N,N,N′,N′-tetrabromobenzene-1,3-disulfonamide as efficient reagents for synthesis of quinolines

Poly(N-bromo-N-ethylbenzene-1,3-disulfonamide) [PBBS] and N,N,N′,N′-tetrabromobenzene-1,3-disulfonamide [TBBDA] were used as efficient reagents for the synthesis of quinolines in excellent yields from 2-aminoaryl ketones and carbonyl compounds under aqueous and solvent-free conditions.     

Single and double bridged viologenes and intramolecular pimerization of their cation radicals

As an extension of our studies dealing with reversible redox systems, six tetraquaternary salts have been synthesized. These compounds contain two 4,4'-bipyridinium units which are connected by either one or two rigid bridges. The single bridged systems (o-, m-3, p-3) contain one o-, m- or p-xylylene bridge. The double bridged systems (o,o-4, o,m-4 and m,m-4) contain two xylylene bridges and represent a new class of cyclophanes. A new and very simple high dilution technique is described for the synthesis of these compounds. Depending upon ring size, some of the systems show different internal mobility with regard to flipping of the bridges and rotation of the pyridinium rings. By voltammetry of compounds 3 and 4, only two or three of the expected four potentials are observed. This is probably due to the highly stabilized diradical dications 3_SEM/SEM and 4_SEM/SEM. From a study of the concentration and temperature dependent UV/VIS spectra of the cation radicals, the equilibrium constants K₁ and K₂ for intra- and intermolecular pimerization (CT complexation) together with their thermodynamic data are evaluated. The strongest intramolecular pimerization is observed with o-3_SEM/SEM and o,o-4_SEM/SEM, which exist exclusively as pimers.     

1,2-bis(3-carboxyacryloyl)hydrazine—IV. Transmidation and addition reactions of 1,2-bis(3-carboxyacryloyl)hydrazine with aromatic diamines

A new method for the synthesis of aromatic poly(amino-maleimides) via polytransamidation followed by polyaddition and ring closure of 1,2-bis(3-carboxyacryloyl)hydrazine (BCAH) with aromatic diamines was found, using the processes between BCAH and anilines. Poly(aminomaleimides) were prepared either in situ or by the separation of poly(α-aminoaryl)amido-succinamic acids. Cyclodehydrations of polysuccinamic acids were carried out in DMF in the presence of Ac₂O or PPA; in m. cresol as solvent, mixtures of polysuccinamic acids and polymaleimides were obtained. The resulting thermostable polymers were characterized by elemental, spectral and thermal analyses, viscosities and solubilities. They gave transparent brittle films.     

Reactions of ortho oxy-substituted benzyl and phenacyl bromides in dimethyl sulphoxide

o-Acetoxy- and o-benzoyloxy-benzyl bromides and tosylates oxidatively rearrange in moist dimethyl sulphoxide to o-hydroxybenzyl esters; o-acetoxy- and o-benzoyloxy- phenacyl bromides rearrange to mixtures of 2-hydroxycoumaran-3-ones and o-hydroxyphenacyl esters; o-hydroxyphenacyl bromides also yield 2-hydroxycoumaran-3-ones, together with o-hydroxyphenacyl alcohols. 2-Acetoxybenzaldehyde is reductively rearranged by sodium borohydride to o-hydroxybenzyl acetate.     

On the reaction of 3-bromo-2-nitrobenzo[b]thiophene with some ortho-substituted anilines: an analysis of the products of reaction and of their NMR and MS properties

The title reaction, carried out in DMF in the presence of triethylamine or potassium carbonate, has furnished the ‘expected’ 3-amino-2-nitrobenzo[b]thiophenes 2o together with the ‘unexpected’ 2-amino-3-nitrobenzo[b]thiophenes 3o, thus recalling the situation observed with other weak nucleophiles in the presence of non-nucleophilic bases. The effects (electronic as well as steric) of the ortho-substituent (OH, NH₂, OMe, Me, Et, F, Cl and Br) on the course of the reaction have been investigated, determining their influence on yields and product ratios (2o/3o). An analysis of ¹³C NMR and MS spectra of 2o and 3o has been carried out. Ab initio computations on 2of, 2oi, 3of and 3oi at DFT level have furnished informations on their geometry and stability in the gas phase, thus allowing to assign a role to their stability on the course of the reaction as well as on some EI-MS results.     

Synthesis of carborane analogues of γ-aminobutanoic acid

General method for preparation of high yields of novel N-protected carborane amino acid derivatives, 3-acylamino-1-carboxymethyl-2-R-o-carboranes (R = H, Me, Ph), is reported. The synthesis starts from readily available 3-amino-o-carboranes and includes the protection of amino group, introduction of carboxymethyl function to the carbon atom of polyhedron via the metallation of carborane CH bond with sodium amide in liquid ammonia, and treatment of corresponding sodium carboranes with sodium bromoacetate. Deprotection of N-acylated carborane amino acids is studied in acidic media. Depending on the procedure employed, closo- or nido-carborane amino acids were obtained.     

A convenient synthesis of quinolines by reactions of o-isocyano-β-methoxystyrenes with nucleophiles

2,4-Disubstituted quinolines have been synthesized by reactions of o-isocyano-β-methoxystyrenes, which can be easily prepared from commercially available o-aminophenyl ketones in three steps, with alkyl(or aryl)lithiums in generally good yields. Subsequently, o-isocyano-β-methoxystyrenes have also proved to react efficiently with lithium dialkylamides to afford the corresponding 4-substituted N,N-dialkylquinolin-2-amines in satisfactory yields.     

Microdetermination of o-aminophenol and some substituted o-aminophenols using a copper ion-selective electrode

The compound o-aminophenol and some substituted o-aminophenols were determined on the microscale by potentiometric titration with standard cupric sulfate or nitrate in aqueous or partially methanolic medium. Emf's were monitored with a copper ion-selective electrode and a single-junction reference electrode. The o-aminophenols reacted on a 2:1 amine:Cu basis. The m- and p-isomers cannot be determined with cupric ion.