Palladium-catalyzed desulfitative arylation of azoles with arylsulfonyl hydrazides

Palladium-catalyzed desulfitative and denitrogenative arylation of azoles with arylsulfonyl hydrazides has been achieved. A broad scope of azoles and arylsulfonyl hydrazides has been used to produce arylated azoles in high yields.     

Diazocarbonyl and Related Compounds in the Synthesis of Azoles

Diazocarbonyl compounds have found numerous applications in many areas of chemistry. Among the most developed fields of diazo chemistry is the preparation of azoles from diazo compounds. This approach represents a useful alternative to more conventional methods of the synthesis of azoles. A comprehensive review on the preparation of various azoles (oxazoles, thiazoles, imidazoles, pyrazoles, triazoles, and tetrazoles) from diazocarbonyl and related compounds is presented for the first time along with discussion of advantages and disadvantages of «diazo» approaches to azoles.     

Palladium-catalyzed desulfitative C-H arylation of azoles with sodium sulfinates

A palladium-catalyzed desulfitative C-H arylation of azoles with sodium sulfinates using Cu(OAc)(2)·H(2)O as oxidant has been discovered. The reaction proceeded well for a range of different substrates under oxidative conditions. A series of aryl-substituted azoles have been synthesized in moderate to good yields.     

Direct amidation of azoles with formamides via metal-free C-H activation in the presence of tert-butyl perbenzoate

A novel and simple method for the direct amidation of azoles with formamides has been developed. The reaction could occur smoothly in the presence of tert-butyl perbenzoate (TBPB) as an oxidant under metal- and base-free conditions. Direct dehydrogenative cross-coupling of formamides and azoles generated the corresponding products in good yields.     

Synthetic applications of azolium ylides to a traceless solid-phase synthesis of 2-substituted azoles

A new approach for the preparation of 2-substituted azole libraries using a polystyrene-carbamyl chloride resin in a traceless fashion is described. Azole substrates II are assembled in a one-pot condensation reaction of azoles and aldehydes with a resin-bound carbamyl chloride. Treatment of the azolyl-carbamate II with boron trifluoride etherate under thermal or microwave-assisted solvolysis conditions afforded 2-substituted azoles. [reaction: see text]     

Synthesis of indolizines and pyrrolo[2,1-b]azoles from 2-pyridylmagnesium bromide and 2-lithiated azoles using tris(alkylthio)-cyclopropenyl cations as a three-carbon building block

A convenient method for the preparation of indolizines 3 and 4 and pyrrolo[2,1-b]azoles 7a-e from 2-pyridylmagnesium bromide and 2-lithiated azoles 6a-e , respectively, was developed by using tris(tert-butylthio)- and tris(isopropylthio)cyclopropenyl cations 1 and 2 as a three-carbon building block.     

Arenium cation as the key intermediate of the electrosynthesis of <Emphasis Type="Italic">N</Emphasis>-(2,5-dimethoxyphenyl)azoles. A new approach to the synthesis of <Emphasis Type="Italic">N</Emphasis>-(dimethoxyphenyl)azoles

Data on the effect of the acid-base properties of the medium on the yield and composition of the products of N-dimethoxyphenylation of azoles (pyrazole, triazole, their substituted derivatives, and tetrazole) upon galvanostatic electrolysis of azole—1,4-dimethoxybenzene mixtures in nucleophilic (MeOH) and neutral (MeCN) media were considered and the trends of this process were discussed. The generation of arenium cations (1,4-dimethoxy-1-azolylbenzenium in MeCN and 1,1,4-trimethoxybenzenium in MeOH) as the key intermediates of electrosynthesis of N-(dimethoxyphenyl)azoles, was proved experimentally. A new approach to the synthesis of N-(dimethoxyphenyl)azoles through electrosynthesis of 1,1,4,4-tetramethoxycyclohexa-2,5-diene by electrooxidation of 1,4-dimethoxybenzene in MeOH as the first step and the reaction of this quinone diketal with azoles as the second step was suggested. The efficiency of this route to N-(dimethoxyphenyl)azoles is comparable with the efficiency of the purely electrochemical one-step process. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2101–2109, November, 2007.     

N-polyazolylmethanes. 1. Synthesis and nmr study of N,N′-diazolylmethanes

Thirteen N,N-diazolylmethanes, including derivatives of pyrazole, imidazole, 1,2,4-triazole, benzimidazole and indazole were prepared by reaction of azoles with methylene chloride under phase transfer catalysis conditions. The relative amounts of isomeric mixtures obtained with ‘asymmetric’ azoles or with equimolar mixtures of azoles are compared with literature results on monoalkylation of azoles. Proton and carbon-13 nmr spectra of the N,N'-diazolylmethanes are discussed.     

Investigation of the electrosurface properties of NiO and Fe2O3 in azole solutions

The electrokinetic study of heterogeneous system consisting of Ni(II) and Fe(III) oxide powders in aqueous azole solutions is presented. Diazole, triazole and tetrazole were used in our experiments. Various combinations of operating conditions such as pH, electrolyte and azole concentrations were employed. Zeta-potentials of powders with adsorbed azoles were obtained in order to investigate the interactions occurring between azoles and the oxide surfaces. In the presence of azoles the equilibration process of zeta-potential of oxide surfaces has a very special “damping oscillation” character and the equilibration process continues for around a week. However, kinetics of adsorption of azoles is completed in approximately 3 h. The latter shows a complex behaviour of adsorbed azoles on oxide surfaces.     

Determination of azoles in sewage sludge from Spanish wastewater treatment plants by liquid chromatography-tandem mass spectrometry

A simple and rapid analytical method for the determination of 16 azoles in sewage sludge has been developed and validated. The method was based on ultrasound-assisted extraction followed by dispersive solid-phase extraction cleanup and liquid chromatography-electrospray tandem mass spectrometric detection. The azoles were selected by their intensive usage as biocides (tebuconazole, propiconazole, cyproconazole and thiabendazole), antimycotic pharmaceuticals (ketoconazole, econazole, fluconazole and clotrimazole) or fungicides in agriculture (difenoconazole, flusilazole, hexaconazole, prochloraz, bromuconazole, epoxiconazole and triticonazole). The recoveries of these compounds through the method were between 71.9 and 115.8%, with relative standard deviations lower than 20%. Detection limits were in the range of 0.5-5.0 ng/g. The developed method was applied to the analysis of azoles in sewage sludge samples collected from 19 Spanish wastewater treatment plants. Although azoles used as biocides or agriculture fungicides were present in a few sludge samples, the pharmaceuticals ketoconazole, econazole and clotrimazole were present in all of the analyzed sludge samples, being ketoconazole the one found at the highest level, representing the 68.6% of the total azole content found in the 19 sludge samples studied.     

Direct C2-alkylation of azoles with alcohols and ethers through dehydrogenative cross-coupling under metal-free conditions

A metal-free novel, simple, and highly efficient method for the direct C2-alkylation of azoles with alcohols and ethers has been developed on the basis of an oxidative C-H activation process. The dehydrogenative C-C cross-coupling reactions of α-position sp(3) C-H in alcohols and ethers with the 2-position sp(2) C-H in azoles proceeded smoothly in the presence of tert-butyl hydroperoxide (TBHP) under neat reaction conditions, which generated the corresponding products in good yields.     

Ligand and solvent-free iron catalyzed oxidative alkynylation of azoles with terminal alkynes

A highly efficient and versatile iron catalyzed oxidative alkynylation of azoles with terminal alkynes under ligand and solvent-free conditions is described.     

The nature of ferrocenylalkylating agent in the acid-catalyzed reactions with ferrocenyl(phenyl)methanol

Russian Chemical Bulletin - The reaction of α-ferrocenyl(phenyl)methanol with various azoles under the phase transfer catalysis conditions afforded a series of ferrocenyl(alkyl)azoles in high...     

One-pot synthesis of benzofused heteroaryl azoles via tandem C-heteroatom coupling/C-H activation of azoles

The Cu(I) or Pd(II)-catalyzed cross-couplings of gem-dihaloolefins with azoles via tandem C-heteroatom coupling/C-H activation for the preparation of benzofused heteroaryl azoles have been developed.     

Spiro-Azoles Thiazolidinone in the Synthesis of Polymethine Cyanine Dyes

A series of some spiro azoles (pyrazolone, oxazolone, and/or imidazolone) inconjucton with heterocyclic thiazolidinone derivatives were prepared as starting materials in the synthesis of polymethine cyanine dyes. Reaction of spiro 2-formyl (oxime) azoles thiazolidinone derivatives with equi- and/or molar ratios of 2(4)-methyl substituted heterocyclic quaternary salts afforded the corresponding compound pentamethine, aza-mero cyanine, and azapentamethine cyanine dyes respectively. Elemental analyses, IR, 1 H-NMR, and mass-spectra identified the new spiro heterocyclic compounds and polymethine cyanine dyes. The visible absorption spectra of all new polymethine cyanine dyes were investigated.     

Dipole moments and azole structures (review)

Data on the dipole moments of azoles are correlated and systematized. The possibilities of the method of dipole moments in the solution of a number of problems of the chemistry of azole-containing systems — the electronic structures of azoles, intermolecular association, tautomeric and conformational equilibria, and reactivities — are demonstrated. The experimental values of the dipole moments of azoles are tabulated.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 867–892, July, 1971.     

Research on the chemistry of heterocycles at Rostov State University (review)

A summary of the research on the chemistry of heterocyclic compounds conducted at Rostov State University is given. The results of research on the chemistry of azoles conducted in Rostov from 1957 to 1982 are presented. The data obtained relative to the chemistry of benzimidazole and other condensed azole systems (imidazo[1,2-a]benzimidazole and indazole) and the chemistry of 2-diazo- and 2-azobenzimidazoles, unsaturated compounds in the azole series, and organometallic derivatives of azoles are examined.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1589–1604, December, 1982.     

Synthesis of new azolyl azoles and azinyl azoles

Synthesis of new azolyl azoles and azinyl azoles from the reaction of compounds 1, 4 and 7 with phenyl isothiocyanate is reported. Compound 10 reacts with benzene diazonium chloride to yield either phenylhy‐drazones 11 and 12 or the triazoloquinoline 13 .     

Basicity of azoles. IV. Empirical relationships between basicity and ionization potential for aromatic five membered rings containing nitrogen or oxygen

A plot of pK_a values for eleven azoles and benzazoles vs the experimental ionization energy of the nitrogen lone pair shows the existence of three groups of compounds: simple unsubstituted azoles (imidazole, pyrazole, oxazole, isoxazole), unsubstituted benzazoles (benzimidazole, 1H-indazole and benzoxazole, including imidazo [1,2-a]pyridine) and benzazoles carrying a methyl group α- to the basic centre (2-methylbenzimidazole, 2-methylindazole and 2-methylbenzoxazole).     

Complexes of azoles with acetylacetonates

A number of the most important inorganic biological systems are coordination adducts formed as a result of the axial addition of azoles to chelates of the transition metals [1].