Synthesis of bis(indolyl) methanes catalyzed by Schiff base-Cu(Ⅱ) complex

Schiff base-Cu(Ⅱ) complex is found to be an effective catalyst for the condensation reaction of indole with aldehydes using ethanol as the solvent.The characterization of the catalysts was carried out using XRD and FT-IR.     

A practical synthesis of bis(indolyl)methanes catalyzed by BF_3·Et_2O

Practical BF3Et2O catalyzed reactions between indoles and a series of carbonyl compounds at room temperature are described, which afford bis(indolyl)methanes with isolated yields up to 96%.     

Polyvinylsulfonic acid as a novel Brønsted acid catalyst for the synthesis of bis(indolyl)methanes

Abstract

Polyvinylsulfonic acid as a novel, biodegradable, and efficient Brønsted acid catalyst for the reaction of indoles with aldehydes to obtain bis(indolyl)methanes has been reported. The catalyst exhibited remarkable activity, recyclability, and tolerated a wide variety of functional groups providing the desired bis(indolyl)methanes in excellent yield (64–96%) at room temperature using ethanol as a solvent. The effect of different reaction parameters like solvent, temperature, catalyst doses, and recyclability were investigated for the title reaction.     

Practical one-pot transformation of electron-rich aromatics into aromatic nitriles with molecular iodine and aq NH3 using Vilsmeier–Haack reaction

Various electron-rich aromatics could be efficiently transformed into the corresponding aromatic nitriles in good to moderate yields by treatment with DMF and POCl₃, followed by the reaction with molecular iodine or 1,3-diiodo-5,5-dimethylhydantoin (DIH) in aq NH₃. Some of less reactive aromatics, such as anisole, 1,2-dimethoxybenzene, 1,4-dimethoxybenzene, and mesityrene, could be also transformed into the corresponding aromatic nitriles in good to moderate yields using N-methylformanilide and O(POCl₂)₂, followed by the reaction with molecular iodine in aq NH₃. Moreover, propiophenone derivatives could be successfully transformed into the corresponding β-chlorocinnamonitriles by the reaction with DMF and POCl₃, followed by the reaction with molecular iodine and aq NH₃. These reactions are novel metal-free one-pot methods for the preparation of aromatic nitriles from electron-rich aromatics and β-chlorocinnamonitriles from propiophenones.     

One-pot aromatic amination based on carbon–nitrogen coupling reaction between aryl halides and azido compounds

An efficient copper-mediated C–N coupling reaction between various aryl halides and azido compounds to produce the corresponding aromatic primary amines was established. The present amination is apparently involved in both the reduction of an azido functionality to the corresponding primary amino group and its cross-coupling reaction with aryl halides in a one-pot manner. The present amination could be applied to the synthesis of procaine, a local anesthetic drug. A mechanistic study indicated that 2-aminoethanol could work as a major hydrogen donor and the reaction would proceed without the formation of the intermediary aryl azide.     

Synthesis of 12-oxobenzo[c]phenanthridinones and 4-substituted 3-arylisoquinolones via Vilsmeier–Haack reaction

Vilsmeier–Haack reaction on 3-arylisoquinolones resulted in versatile 4-formylated 3-arylisoquinolones that were further derivatized into 12-oxobenzo[c]phenanthridinones, 4-alkoxymethyl-3-arylisoquinolones, 3-aryl-4-phenoxymethylisoquinolones, 4-aminomethyl-3-arylisquinolone, and 3-isoquinolinyl-2-phenyl-acrylonitrile by different synthetic strategies.     

A facile approach for the synthesis of novel xanthene derivatives with Vilsmeier–Haack reagent

Chemistry of Heterocyclic Compounds - A series of new derivatives of formylxanthenes have been synthesized via the reaction of substituted 1,3-benzoxazines with Vilsmeier–Haack reagent. It...     

N,N’-dimethyl formamide (DMF) mediated Vilsmeier–Haack adducts with 1,3,5-triazine compounds as efficient catalysts for the transesterification of β-ketoesters

Abstract

N, N’-dimethyl formamide (DMF) mediated Vilsmeier–Haack (VH) adducts with 1,3,5-triazine compunds such as trichloroisocyanuric acid (TCCA) and trichlorotriazine (TCTA) were prepared by replacing classical oxy chlorides POCl₃, and SOCl₂, which were explored as efficient catalysts for the transesterification of β-ketoesters. The prepared (TCCA/DMF) and (TCTA/DMF) adducts improved greenery of the classical Vilsmeier–Haack reagents (POCl₃/DMF), and (SOCl₂/DMF), and demonstrated their better efficient catalytic ativity. Reaction times were in the range: 3.5 to 6.5?hr (SOCl₂/DMF); 2.8–5.2?hr (POCl₃/DMF); 2.5–5.2?hr (TCCA/DMF) and 2.5–5.0?hr (TCTA/DMF) catalytic systems. Ultrasonically (US) assisted protocols with these reagents further reduced the reaction times (two to three times), while microwave assisted (MW) protocols with these reagents were much more effective. The reactions could be completed in only few seconds (less than a minute) in MWassisted protocols as compared to US assited reactions, followed by good product yields.     

First synthesis of 1-(indol-2-yl)azulenes by the Vilsmeier–Haack type arylation with triflic anhydride as an activating reagent

Azulene derivatives reacted with 2-indolinones in the presence of triflic anhydride (Tf₂O) to afford 1-(indol-2-yl)azulenes in good yields. In the cases of the reaction of 6-tert-butyl-1-(methylthio)azulene (11) and 1-(1,4-dihydropyridin-4-yl)azulene 14, 1,1′-biazulene derivative 24 and 1-(indol-2-yl)azulene (2) were obtained under the similar reaction conditions, respectively, instead of the presumed electrophilic substitution products.     

RuCl₃·3H₂O catalyzed reactions: facile synthesis of bis(indolyl)methanes under mild conditions

RuCl?·3H?O was found to be an effective catalyst for reactions of indoles, 2-methylthiophene, and 2-methylfuran with aldehydes to afford the corresponding bis(indolyl)methanes, bis(thienyl)methanes, and bis(fur-2-yl)methanes in moderate to excellent yields. Experimental results indicated that mono(indolyl)methanol is not the reaction intermediate under these reaction conditions.     

Nucleophilic addition reaction of aromatic compounds with α-chloroglycidates in the presence of Lewis acid

The epoxide 1 obtained by the Darzens condensation reaction of aldehydes with methyl dichloroacetate, reacted with aromatic compounds in the presence of aluminium chloride to afford α-aryl-β-chloro-α-hydroxyalkanoate 3. The intra-molecular nucleophilic addition of epoxide 1′ gave cyclisation compound 4. The scope and limitation of these reaction were studied for various aldehydes and aromatic compounds. The reaction was also studied in the presence of aluminium chloride supported on alumina or silica gel, which is thought to be a mild Lewis acid and harmless for environment.     

The single-crystal electron spin resonance spectra of bis chloro bis(N,N′-substituted urea)oxovanadium(IV) compounds diluted in the corresponding tris-chloro bis(N,N′-substituted)urea indium(III) compounds

Single crystal ESR spectra of VOCl₂L₂ (where L = N, N, N′, N′-tetramethyl urea (tmu), N, N′-dimethylethyleneurea, N, N′-dimethylpropyleneurea, tris(dimethylamino)phosphincoxide) diluted in the corresponding Inøcl₃L₂, at Q-band frequencies are reported. The ESR data are consitent with C₂ point symmetry for VOCl₂(tmu)₂ whilst the other compounds approximate very closely to this point symmetry. A rotation of the g and A tensor axes in the plane perpendicular to the terminal VO vector fall in the range 8–15° for the four compounds studied. The spin Hamiltonian parameters for VOCl₂(tmu)₂, in conjunction with the published polarized electronic absorption spectra, have been analysed via angular overlap calculations. For VOCl₂(tmu)₂ unusual ligand hyperfine splittings were observed. These were analysed by spectrum simulation in terms of two equivalent chlorine atoms where the chlorine hyperfine and nuclear quadrupole tensors are of comparable magnitude.     

One-pot synthesis of oxoisoindoline-1,2,3-triazole hybrid by a Ugi–click reaction

1,2,3-Triazole-3-oxoisoindoline-1-carboxamide system was successfully synthesized by using a combination of Ugi and click reactions. This two-step, one-pot synthesis was started by the reaction of 2-formyl benzoic acid, propargyl amine, and cyclohexyl isocyanide in ethanol. The resultant Ugi adduct underwent a copper-catalyzed click reaction, producing the desired products in good yields.     

Asymmetric copper-catalyzed Diels–Alder reaction revisited: control of the structure of bis(oxazoline) ligands

Synthesis of 1,4-bis(oxazoline) ligands bearing a bicyclo[2,2,2]backbone derived from 9,10-dihydro-9,10-ethanoanthacene trans-dicarboxylic acid was revisited. Starting from l- or d-amino alcohols and either (S,S) or (R,R)-dihydroethano trans-dicarboxylic acid, a complete series of ligands was evaluated in the copper-catalyzed Diels–Alder reaction. The most efficient ligands with a phenyl substituent on the oxazoline ring afforded enantiomeric excess up to 98%. This is different from previous results indicating that the best enantioselectivity involved a diastereomeric ligand with the meso-backbone.     

Convenient synthesis of bis(indolyl)alkanes by dithiocarbohydrazone Schiff base/Zn(ClO_4 )_2 6H_2 O catalyzed Friedel–Crafts reaction of indoles with imines

A new, convenient and excellent yield procedure for the preparation of bis(indolyl)methanes(BIMs) by Friedel–Crafts reaction of indoles with imines in the presence of dithiocarbohydrazone Schiff base/ Zn(ClO4)2 6H2 O as a highly stable, effective and readily available catalyst is described. Moderate to good yields(up to 99% yield) were obtained with both substrates for imine derivatives. This procedure is simple, practical and economic.     

Reversal of enantioselection in an aldol reaction catalyzed by sterically congested bis(oxazoline)–Cu(II) complexes

The use of sterically congested C₂-symmetrical bis(oxazoline) ligands with methylene and ethylene spacers between the oxazoline rings results in the reversal of the enantioselection for aldol reactions catalyzed by bis(oxazoline)–Cu(II) complexes.     

Synthesis of Bis(indolyl)methanes using a Catalytic Amount of ZnO under Solvent‐Free Conditions

Efficient electrophilic substitution reactions of indoles with various aromatic aldehydes were carried out using a catalytic amount of ZnO under solvent‐free conditions to afford the corresponding bis(indolyl)methanes in excellent yields. Among the various methods published for the synthesis of bis(indolyl)methane, ZnO is a very cheap, environmentally friendly, and reusable catalyst that can be used for synthesis of a new range of bis(indolyl)methane derivatives.     

Fine tuning of the Cd(II)–bis(benzimidazole) networks by changing carboxylate anions

Three new polymeric frameworks, [Cd(bbbi)(ita)(H₂O)]?·?H₂O (1), [Cd(bbbi)(fma)] (2), and [Cd(bbbi)(fma)(H₂O)]?·?2H₂O (3) (bbbi?=?1,1-(1,4-butanediyl)bis-1?H-benzimidazole, H₂ita?=?itaconic acid, and H₂fma?=?fumaric acid), have been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction. Complex 1 is a 2-D (4,4) network containing infinite 1-D zigzag Cd(II)-bbbi chains linked by auxiliary ita ligands. In the structure of 2, infinite 1-D linear Cd(II)-bbbi chains are linked by fma ligands to generate an undulated 2-D (4,4) network. In 3, an in situ ligand transformation occurred with malate converted to H₂fma by dehydration. Thus, a 2-D (4,4) grid network constructed from bbbi and fma was obtained. The carboxylates with different substituents play an important role in the formation of the final frameworks and coordination modes of Cd(II). Thermal stability and luminescent properties of 1–3 were investigated.     

The role of the Baeyer–Villiger reaction in the liquid-phase oxidation of organic compounds

The data on the composition of ester products formed in the Baeyer–Villiger reaction in the liquid-phase oxidation of organic compounds with molecular oxygen, on production channel of peroxy acids, as well as on the influence of a carbonyl compound structure on its reactivity in reactions with peroxy acids have been classified and considered. The Baeyer–Villiger reaction was shown to be the main source of accessory primary alcohol esters and lactones in industrial processes of aerobic oxidation of cyclohexane and paraffin hydrocarbons.