Pd catalyzed coupling of 1,2-dibromoarenes and anilines: formation of N,N-diaryl-o-phenylenediamines

1,2-Dibromoarenes were coupled with aniline derivatives to yield N,N-diaryl-o-phenylenediamines in moderate to good yield using a palladium/phosphine or palladium/carbene catalyst system. Under similar conditions, 1,2,4,5-tetrabromobenzene was coupled with aniline derivatives to produce the corresponding tetrasubstituted derivatives which are oxidized on workup to yield azophenines. The sequential reaction of two different anilines with 1-chloro-2-iodobenzene afforded mixed N,N-diaryl-o-phenylenediamines.     

Electronic spectra and π-electronic structure of some hydroxyazo dyes

The electronic spectra of some hydroxyazo dyes, derivatives of azobenzene and benzeneazonaphthalene, are investigated and electronic transitions in the UV and visible regions assigned.The difference in spectral assignment of o- and p-hydroxyazobenzenes is explained using MO theory.Observations are made about possible azo—quinonehydrazone tautomerism in o-,m- and p-hydroxy derivatives of 4-phenylazo-1-naphthol and 1-phenylazo-2-naphthol and the quantitative value for the contribution of each tautomeric form is calculated.Calculations using the SCl—Cl method, within the PPP approximation, are performed for some hydroxyazo derivatives. The results of the calculations agreed significantly with the experimental spectral curves. Spectral differences between o- and p-hydroxyazobenzenes are established. It is shown that there is charge transfer from the aromatic rings to the azo group in the first excited singlet state.     

Thermochemistry of aqueous solutions of nucleic acid bases and their alkylated derivatives

Enthalpy of solution, ΔH _sol ^o , enthalpy of sublimation, ΔH _subl ^o , apparent partial molar volume and heat capacities,V ₂ ^o andC _p,2 ^o were determined for aqueous solutions of thirty alkylated derivatives of uracyl and adenine, eight derivatives of cytosine and guanine. Calculated accessible surface areas and molar volumes are presented, too. The values of enthalpy of solution, enthalpy of sublimation can be useful in the studies on the nature of interaction between these compounds and water molecules. Apparent partial molar volume and heat capacity give a new aspect on hydrophob properties of the examined nucleic acid base derivatives.     

Influence des effets de substituants sur la protonation de la pyridine

Standard thermodynamic values of proton ionisation of 3 substituted (Cl?, Br?, I?, C₂H₅? and CH₂CN?) pyridine derivatives are determined at 25°C, in an aqueous medium of ionic strength 0.5 M KNO₃.Free energies are deduced from equilibrium constants log K potentiometrically calculated. Enthalpies are obtained from calorimetric measurements.ΔG^o, ΔH^o and ΔS^o values are discussed in the context of the results of our earlier studies on this subject.The Hammett plot corresponding to the thirteen systems examined gives the proton ionisation constant of a substituted pyridine from the equation log K = 5,48 – 5,94Σσ.Besides, a linear relationship is found between ΔG^o and ΔH^o, which confirms the observation made previously in other series of pyridine derivatives.     

Synthesis of polynuclear aromatic compounds through net [5+5]-cycloaddition of 2-alkynylarylcarbene complexes and enyne-aldehyde derivatives

Coupling of o-alkynylphenylcarbene complexes and -o-alkynylheteroarene carboxaldehydes leads to heterocycle annulated phenanthrene derivatives.     

Organotin derivatives of (arylazo)benzoic acids : I. Preparation,spectrophotometric titrations and IR spectra

Organotin derivatives of some (arylazo)benzoic acids have been prepared, and investigated by spectrophotometric titration and IR spectroscopy. The organotin (o-arylazo)benzoates are generally penta-coordinated, but those containing a hydroxyl group in the 2-position, e.g., triorganotin o-(2-hydroxy-5-methyl-benzeneazo)benzoate, are hexa-coordinated. The tetracarboxy derivatives contain two different types of tin—carboxylate bonds, as shown by two IR absorptions, at 1700 (ester-like) and 1620 cm^?1 (chelated).     

Biphenylenes—XXX: Synthesis and some reactions op 5,10-diazabenzo[b]biphenylenes

Condensation of benzocyclobutene-1,2-dione with 10 derivatives of o-phenylenediamine gave the corresponding benzo-substituted derivatives of 5,10-diazabenzo[b]biphenylene. Attempted oxidative demethylation of 2,3-dimethoxy-5,10-diaza benzo[b]biphenylene gave 2-methoxy-5-phthalimido benzo-1,4-quinone. Other attempts to demethylate methoxy diazabenzobiphenylenes are described. 5,10-Diazabenzo[b]biphenylene was not oxidised by air, lead tetra-acetate, or phenyliodoso diacetate, but with peracetic acid it gave dibenzodiazocine-5,12-dione and o-nitroaniline. Reduction of the diazabiphenylene with Raney nickel gave 2-phenylquinoxaline. The diazabiphenylene is readily hydrolysed by nitric and hydrochloric acid to regenerate benzocyclobutene-1,2-dione and o-phenylenediamine which then recondense to give a mixture of products. A similar hydrolysis occurs with sodium hydroxide     

Structure-property relationship on aggregation-induced emission properties of simple azine-based AIEgens and its application in metal ions detection

In recent twenty years, aggregation-induced emission (AIE), due to its excellent application prospect, has aroused widespread interests. The development of novel and easy to make AIE luminogens (AIEgens) is an attractive subject. For this purpose, it's very important to study the structure-property relationship of AIEgens. Because azine derivatives are easy to synthesis and some of them have nice AIE properties, herein, a series of azine derivatives (ADs) were employed as models to study the influence of different functional groups, electronic effects and structures on the AIE properties of azine derivatives. The AIE mechanism were studied by single crystal analysis, density functional theory (DFT) calculations and so on. The results indicated that the o-hydroxyl aryl substituted azine compounds could show good AIE properties. Meanwhile, the AIE properties of o-hydroxyl aryl substituted azine compounds were also influenced by the electronic effects of the aryl groups in the azine compounds. The o-hydroxyl groups could form intramolecular hydrogen bond with imine group, which play key role to restrict the intramolecular rotation of the aryl groups and act as base stone for the AIE process of this kind compounds. The HOMO-LUMO energy gaps of o-hydroxyl substituted azine are smaller than other homologous compounds, which is agree with the proposed AIE mechanism. Finally, thanks to the AIE properties, the o-hydroxy-substituted azines could be used as efficient Al³⁺ and Cu²⁺ fluorescent chemosensors in different conditions. In addition, test strips based on AD10 has been prepared, which can conveniently detect Cu²⁺ in industrial wastewater. This research supplied a way for the design of novel easy to make AIEgens through simple azine derivatives.     

Synthesis, structures, and properties of peripheral o-dimethoxy-substituted pentiptycene quinones and their o-quinone derivatives

A series of peripheral o-dimethoxy-substituted pentiptycene quinones and their o-quinone derivatives have been synthesized. Especially, it was found that if two o-dimethoxybenzene moieties were situated at the same side of the pentiptycene quinones, one of them was only oxidized by excess CAN in aqueous acetonitrile. Moreover, the pentiptycene quinones with unique 3D rigid structure could all self-assemble into a 3D microporous structure in the solid state. For the pentiptycene quinones containing the dimethoxybenzene unit(s) and the quinone group(s) simultaneously, interesting intramolecular charge transfer interactions and electrochemical properties were also shown. These peripheral-substituted pentiptycene quinones and their o-quinone derivatives can be used as new useful building blocks and will find wide applications in material science and host-guest chemistry.     

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.     

Verbanone in the synthesis of amidoketones from o-menthane series

A verbanone reaction with acetonitrile under Ritter reaction conditions led to a selective formation of o-menthane derivatives, a mixture of stereoisomeric cis-and trans-8-acetamido-o-menthones. The streoisomers ratio depends on the reaction conditions and the character of acid catalyst used.     

Silver-catalyzed cascade reaction of o-aminoaryl compounds with alkynes: an aniline mediated synthesis of 2-substituted quinolines

An efficient silver-catalyzed, aniline mediated cascade hydroamination/cycloaddition of o-aminoaryl compounds including o-aminoaryl aldehydes, o-aminoaryl ketones with alkynes for the synthesis of 2- or 2,4-substituted quinolines is reported. The reactions proceed with high regioselectivity to afford mono- or disubstituted quinoline derivatives in good to high yields using AgOTf as the catalyst in the air.     

Synthesis of o-nitrosoacylbenzenes from o-nitrobenzyl alcohols and their derivatives

Nitration of substituted benzyl alcohols, as well as ethers and esters derived therefrom, with nitric acid in acetic anhydride was studied. The corresponding o-nitrobenzyl alcohols and their derivatives formed as the primary products are capable of being converted into o-nitrosoacylbenzenes by the action of acids.     

Synthesis and characterization of novel chalcogen and pnictogen coordinated Bi(III) complexes—the first Se,Se′ coordinated Bi metallacycle

Inorganic and organometallic Bi(III) complexes with five-membered heterocycles were studied. The preparation, properties, and spectroscopic characterization (¹H NMR, IR, MS-fragmentation behaviour) of the new compounds are reported. The first member of Se coordinated Bi metallacycles is presented. Bi organyles with the o-aminobenzenethiol ligand system, at present widely investigated, are described as o-aminobenzenethiolate and o-aminobenzenethioldiate derivatives.     

Electronic effects of icosahedral carboranes: mechanistic alteration in solvolysis of α-(o-carboranyl)benzyl tosylates by electronic effect of substituents

Solvolysis of α-(o- and m-carboranyl)benzyl toluene-p-sulfonates bearing a range of substituents at the 3- or 4-position of the benzyl group has been investigated. The rates of hydrolysis of m-carboranyl derivatives increased linearly with increasing electron-releasing character of the substituent group (ρ=−5.37 correlated to σ⁺), which indicates that the hydrolysis proceeds through a typical S_N1 process. In contrast, the hydrolysis rates of the o-carboranyl derivatives with a wide range of electron-withdrawing substituents did not show significant change, but suddenly began to show a linear increase with increasing electron-releasing character of the substituents (ρ=−5.91 correlated to σ⁺). Moreover, the optical purity of the retentive hydrolysis of the o-carboranyl derivatives rapidly declined with increasing electron-donating effects of the substituents. This indicates that the mechanism of the hydrolysis changes from the retentive mechanism to an S_N1 mechanism.     

Base-catalyzed Schmittel cycloisomerization of o-phenylenediyne-linked bis(arenol)s to indeno[1,2-c]chromenes

We describe the transition metal-free base-catalyzed Schmittel cycloisomerization reactions of o-phenylene-linked bis(arenol)s to indeno[1,2-c]chromene derivatives through prototropic rearrangement (tautomerization) to a putative vinylidene o-quinone methide intermediate with an enyne-allene system followed by a formal inverse-electron-demand hetero Diels–Alder cycloaddition. The preliminary results on catalytic asymmetric cycloisomerization with chiral bases are also disclosed.     

Highly selective synthesis of triptycene o-quinone derivatives and their optical and electrochemical properties

A convenient and efficient method for the selective synthesis of a series of triptycene o-quinone derivatives is described. The triptycene o-quinones, especially the ones containing the methoxy group(s) (electron donor) and the o-quinone group(s) (electron acceptor) simultaneously, show interesting intramolecular CT interactions and electrochemical properties. Moreover, DFT calculations display that introducing a strong electron-donor group into triptycene o-quinone results in an increasing of the HOMO energy level, which subsequently decreases the HOMO-LUMO energy gap.     

Zinc and cadmium complexes based on 3,6-di-tert-butyl-o-benzoquinone

Zinc and cadmium bis-o-semuquinolate and catecholate complexes are synthesized by the reduction of 3,6-di-tert-butyl-o-benzoquinone (3,6-Q) with amalgamated metals in a medium of various solvents. The oxidation of the metal catecholate derivatives results in the corresponding mono-o-semiquinone complexes, which undergo symmetrization to form the metal bis-o-semiquinolates. The molecular structures of the complexes (3,6-SQ)₂Zn · Py, (3,6-SQ)₂Zn · H₂O, and (3,6-SQ)₂Cd · α,α′-Bipy (3,6-SQ is the radical anion of 3,6-Q) are studied by X-ray diffraction analysis. Magnetochemical studies are carried out for the zinc and cadmium bis-o-semiquinone complexes.     

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.     

Stereoselective synthesis of fused heterocycles from substituted o-Benzoquinones and anilines

The reaction of trisubstituted o-benzoquinones with substituted anilines gives unstable o-benzoquinone imines which undergo intramolecular cyclization to 4aH-phenoxazine derivatives. Dimerization of the latter according to Diels-Alder yields complex heterocyclic systems, 7a,14a,15a,15b-tetrahydro-14,16-dioxa-5,9-diaza-8,15-ethenohexaphenes. Effective shielding of the carbonyl groups in 3,6-di-tert-butyl-4-isopropyl-o-benzoquinone makes it inactive toward substituted anilines.