Reactions of 1,2-diaminobenzimidazoles with β-dicarbonyl compounds

The reactions of 1,2-diaminobenzimidazoles with β-dicarbonyl compounds give 1,2,4-triazepino [2,3-a]benzimidazole and pyrimido [1,2-a]benzimidazole-derivatives.     

γ-hydroxypropylation of 2,6-dialkyl(aryl)phenols with allyl alcohol and its derivatives

The composition of the products of the reaction of 2,6-disubstituted phenols with allyl alcohol and its derivatives in an alkaline medium was investigated, the conditions for carrying out the reaction with the predominant formation of 4-(3-hydroxypropyl)-2,6-dialkyl(aryl)phenols were found, and its mechanism was suggested. The reaction was examined on an industrial scale. An important result is the practical demonstration of alkaline catalysis performed under homogeneous conditions with participation of phenols, when the used alkaline catalyst is recovered in the process without the formation of waste waters.     

Highly diastereoselective synthesis of tetrahydrobenzofuran derivatives by palladium-catalyzed reaction of propargylic esters with substituted β-dicarbonyl compounds

Reactions of propargylic esters with 2-substituted cyclohexane-1,3-diones and 2-oxocyclohexanecarboxylic esters in the presence of palladium catalyst are described. Substituted tetrahydrobenzofuran derivatives having a quaternary carbon stereocenter were synthesized in a highly diastereoselective manner.     

Reactions of (arene)tricarbonylchromium stabilized carbocations with aromatics and β-dicarbonyl compounds

Primary and secondary benzylic carbocations, stabilized by a tricarbonyl-chromium group, gave coupling products with several aromatics or β-dicarbonyl compounds in good yield and this reaction presents a new synthetic method for carbon-carbon bond formation. The chromium complexes of tertiary benzyl alcohols gave dehydrated products without carbon-carbon coupling products under similar conditions.     

Synthesis of 1,3-thiazoline derivatives from β-dicarbonyl compounds and phenacyl thiocyanate

Acetylacetone and ethyl acetoacetate undergo addition at the CN bond of phenacyl thiocyanate in the presence of Ni(acac)₂ to give the respective keteneN, S-acetals, which undergo smooth cyclization to afford 2-methylene-4-phenyl-1, 3-thiazoline derivatives when refluxed in THF.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1938–1940, November, 1993     

Base-promoted O-deprotonation/alkylation reaction of P(O)–OH compounds with alkyl halides

A novel base-promoted O-deprotonation/alkylation reaction of P(O)–OH compounds with alkyl halides has been developed. The protocol is practical, representing a simple way to produce a broad spectrum of functionalized phosphinates, phosphonates, and phosphates from basic starting materials with good to excellent yields. A plausible mechanism was proposed for this reaction.     

Electrochromic and spectroelectrochemical properties of polythiophene β-substituted with alkyl and alkoxy groups

Journal of Solid State Electrochemistry - Polythiophenes are conjugated polymers that are highly promising candidates for use as an active layer in flexible optoelectronic devices. The...     

Studies on the reaction of 3-substituted-4-hydroxy-2H-1,2-benzothiazine 1,1-dioxides with aryl isocyanates and the synthesis of corresponding derivatives

The reaction of 3-substituted-4-hydroxy-2H-1,2-benzothiazine 1,1-dioxides with aryl isocyanate under different equivalents of strong base NaH was studied.Seventeen of new derivatives were obtained whose structures were characterized by 1H NMR,IR,MS,elementary analysis and FeCl3 test.     

A simple and efficient copper oxide-catalyzed Barbier–Grignard reaction of unactivated aryl or alkyl bromides with ester

An efficient one-pot route to synthesize tertiary alcohol compounds using Barbier–Grignard reaction of unactivated alkyl or aryl bromides with ester in THF at 65 °C catalyzed by CuO has been developed and systematically investigated. A wide range of substituted tertiary alcohol compounds were obtained in good to high yields. The reaction is highly chemoselective. The mechanism involving the leaving group of R²O^-group is discussed.     

Multicomponent condensation of 1,2-dihydropyrazol-3-one derivatives with carbonyl compounds and Meldrum´s acid

A convenient method for the synthesis of earlier unknown 3-aryl-3-(3-oxo-2,3-dihydro-1H-pyrazol-4-yl)propionic acid derivatives was developed based on the multicomponent condensation of 1,2-dihydropyrazol-3-ones, carbonyl compounds, and Meldrum´s acid.     

Addition products of hydrazine derivatives to azo-alkenes,part V: The reaction of α-(1-phenylhydrazino)alkanone phyenylhydrazones with acids and acid derivatives

Summary The bifunctional title compounds2 react with acylating, carbamoylating and sulfonylating reagents mostly at the primary amino group of the hydrazine function. Both functional groups of2 are attacked by N,N-carbonyldiimidazole converting it into 1H-1,2,4,5-tetrazepin-3-one derivatives8. The acid-induced 1,4-elimination of phenylhydrazine from2 gives rise to the formation of phenylosazones3. In the presence of thiocyanic acid the intermediately formed phenylazo-alkenes1 undergo [3+2]-cycloaddition furnishing 1-anilino-imidazoline-2-thiones13.

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Additionsprodukte von Hydrazin-Derivaten an Phenylazo-alkene, 5. Mitt.: Umsetzung von -(1-Phenylhydrazino)alkanon phenylhydrazonen mit Säuren und Säurederivaten

Zusammenfassung Die bifunktionellen Titelverbindungen2 reagieren mit Acylierungs-, Carbamoylierungs-und Sulfinylierungs-Reagenzien meist an der primären Amino-Gruppe der Hydrazin-Funktion. N,N-Carbonyldiimidazol greift beide funktionelle Gruppen von2 an und bedingt die Umwandlung in 1H-1,2,4,5-Tetrazepin-3-on-Derivate8. Die säureinduzierte 1,4-Eliminierung von Phenylhydrazin aus2 führt zur Bildung der Phenylosazone3. In Gegenwart von Thiocyansäure erfolgt [3+2]-Cycloaddition an die intermediär gebildeten Phenylazo-alkene1, sodaß 1-Anilino-imidazolin-2-thione13 entstehen.

     

Gas-Phase reactions of O 2 −. with alkyl and aryl esters of benzenedicarboxylic acids

The reactions of O ₂ ^?. with alkyl and aryl esters of benzenedicarboxylic acids have been studied under negative-ion chemical ionization (NICI) conditions via a conventional chemical ionization source. Reaction mechanisms have been elucidated by using ion isolation techniques on a Fourier transform ion cyclotron resonance mass spectrometer. In addition, ¹⁸O ₂ ^?. has been used as the reagent and the products of competitive reactions that involve the mixed esters of benzenedicarboxylic acids have been studied. O ₂ ^?. reactions with the alkyl esters of 1,2- and l,3-benzenedicarboxylic acids are attributed to S_N2 displacement at the O-alkyl carbon. The spectra of mixed alkyl esters show that O ₂ ^?. attack is reduced at sterically hindered alkyl groups. In contrast with the spectra of 1,2- and l,3-benzenedicarboxylic acids, the spectra of 1,4-benzenedicarboxylic acids are dominated by M^?. production. Reactions of O ₂ ^?. with phenyl benzoates and the aryl esters of benzenedicarboxylic acids proceed via addition-elimination pathways. Experiments with mixed alkyl-aryl benzenedicarboxylic acid esters show that the addition-elimination reaction pathway is preferred over O-alkyl S_N2 displacement. The O₂/ Ar-NICI mass spectra show features that can be used to distinguish 1,2-, 1,3-, and 1/4-benzenedicarboxylic acid esters. Molecular and fragment ions provide structural information complementary to that generated under electron ionization and chemical ionization conditions.     

Synthesis, structure, and antimicrobial activity of copper(II) chelates containing imidazole and condensation products of α-amino acids with salicylaldehyde and its derivatives

Salicylaldehyde, 5-bromo- and 5-nitrosalicylaldehydes, 2-hydroxynaphthalene-1-carbaldehyde, and 2,3-, 2,4-, and 2,5-dihydroxybenzaldehydes reacted with glycine, alanine, and phenylalanine in ethanol in the presence of imidazole (Im) and copper(II) acetate hydrate to give copper(II) chelates with the composition Cu(Im)(L) · nH₂O (H₂L is the condensation product of the above aldehydes with α-amino acids; n = 0–2). The structure of the complex Cu(Im)(L¹) [H₂L¹ = 2-(2-hydroxybenzylideneamino)acetic acid] was determined by X-ray analysis. The crystalline structure of [2-(2-hydroxybenzylideneamino)acetato](imidazole)copper is formed by polymeric chains of the Cu(Im)(L¹) molecules linked through bridging oxygen atoms in the carboxy groups of the Schiff base ligand. The coordination unit has a distorted tetragonal pyramid configuration, where the pyramid base is composed of the phenol and carboxy oxygen atoms, CH=N nitrogen atom in the ligand H₂L¹ and imidazole nitrogen atom. The oxygen atom in the carboxy group in the neighboring molecule occupies the apical position of the coordination pyramid. The other coordination compounds also have polynuclear structure with the Schiff base H₂L acting as doubly deprotonated tridentate O,N,O-ligand and bridging carboxy groups. Thermal decomposition of the complexes includes their dehydration (70–95°C), while complete thermal decomposition occurs at 360–530°C. The synthesized complexes showed selective antimicrobial activity in the concentration range from 75 to 300 μg/ml against a number of standard strains of Staphylococcus aureus and Escherichia coli.     

Reactions of N-(Β-aminoethyl)piperazine and its derivatives

The alkylation, cyanoethylation, and heterocyclization reactoins of N-(-amonoethyl)piperazine and its derivatives, dicarboxylic acid imides, have been investigated. A new method has been proposed for the synthesis of 1,4-diazobicyclo[2.2.2]octane via pyrolytic cleavage of N,N-bis[piperazinoethyl]ethylenediamine.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 381–385, March, 1991.     

Thermal and photochemical addition of alkyl and aryl halides to tetrakis(μ-pyrophosphito) diplatinum(II) tetraanion

Alkyl halides RI (R = Me, Et, n-Pr, i-Pr, n-pentyl, CF₃, CH₂I₂) undergo a thermal reaction with Pt₂(pop)₄⁴⁻ (pop = pyrophosphite) to give the axially substituted “lantern” complexes Pt₂(pop)₄RI⁴⁻. For R = Me, the pure complex can be isolated The solution structure has been characterized by a combination of ¹H, ¹³C, ³¹P and ¹⁹⁵Pt NMR spectroscopy. With the higher homologues, (R = Et, n-Pr, i- Pr, n-pentyl) the reaction gives a mixture of Pt₂(pop)₄RI⁴⁻ and Pt₂(pop)₄I₂⁴⁻. A radical pathway is proposed. Aryl halides ArX (X = Cl, Ar = Ph; X = Br, Ar = Ph, p-FC₆H₄, p-HOC₆H₄, p-CH₃OC₆H₄, p-HO₂CCH₄, p-CH₃C₆H₄; X = I, Ar = Ph) photochemically add to the triplet excited state Pt₂(pop)₄⁴⁻ to give Pt₂(pop)₄ArX⁴⁻. For the photochemical reaction with C₆F₅Br, CCl₄, CHCl₃, CH₂ClCO₂H, CH₂BrCO₂H and p-BrC₆H₄NH₃⁺ the product is the dihalo complex Pt₂(pop)₄X₂⁴⁻ (X = Cl, Br).     

Phenylmercury(II) compounds—I: Some novel mononuclear and binuclear phenylmercury(II) compounds with benzimidazole and 2-substituted benzimidazoles

Benzimidazole (BzH) and 2-substituted benzimidazoles [2-methylbenzimidazole (MeBzH), 2-ethylbenzimidazole (EtBzH), 2-hydroxymethyl benzimidazole (HOMeBzH) and 2-guanidinobenzimidazole (GBzH)] react with basic phenylmercuric nitrate to form binuclear organo-mercury(II) complexes of the general formula [C₆H₅ · Hg(L)Hg · C₆H₅]NO₃ where LH is a monoprotic benzimidazole ligand. The complexes are insoluble in common organic solvents but are ionic in nitromethane.Phenylmercuric acetate and phenylmercuric chloride give with benzimidazole complexes: [C₆H₅ · Hg(Bz)] and [C₆H₅ · Hg(Bz)Hg(C₆H₅)Cl] respectively. But 2-methyl benzimidazole and phenylmercuric acetate produce [C₆H₅ · Hg(MeBz)Hg · C₆H₅](CH₃COO).2-(2-Pyridyl) benzimidazole (PyBzH) reacts with phenylmercuric acetate and the basic nitrate to give the same 3-coordinate mononuclear product [C₆H₅ · Hg(PyBz)], while the 2-carboxylic acid derivative of benzimidazole (HBzCOOH) gives with basic phenylmercuric nitrate binuclear [C₆H₅ · Hg(BzCOO)Hg · C₆H₅].2-(o-hydroxyphenyl)benzimidazole (HOPhBzH) reacts with basic phenylmercuric nitrate to give a non-electrolyte binuclear complex [C₆H₅ · Hg(OPhBz)Hg · C₆H₅].     

Synthesis and crystal structure of 2′-(3,5-dioxo-1,2,4-triazinane-1-yl)acetic acid and the product of its reaction with copper(II) chloride

A new organic compound, 2-(3,5-dioxo-1,2,4-triazinane-1-yl)acetic acid, was prepared by transit template synthesis, and its crystal structure was determined. The ability of this compound to form stable metal complexes, where it acts as an N,O-chelating ligand, was demonstrated using its Cu(II) compound as an example.Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 3, 2005, pp. 187–194.Original Russian Text Copyright © 2005 by Filippova, Bologa, Simonov, Gdaniec, Gerbaleu.This revised version was published online in April 2005 with a corrected cover date.This revised version was published online in April 2005 with a corrected cover date.     

Suzuki–Miyaura cross-coupling reaction of aryl and heteroaryl pinacol boronates for the synthesis of 2-substituted pyrimidines

Suzuki–Miyaura cross-coupling reaction with 2-heteroarylboronic acids is generally challenging due to these acids easy decomposition. To overcome this problem, we developed a coupling method that uses 2-heteroaryl pinacol boronates in the presence of 1.0 mol % Pd(OAc)₂ and 2.0 mol % S-Phos with 4 equiv amount of LiOH in dioxane and H₂O at 80 °C for 30 min. This developed method allowed for the synthesis of a wide variety of 2-heteroaryl pyrimidines from 2-chloropyrimidyl derivatives in high yields, and is also useful in the preparation of various biaryl derivatives from heteroaryl chlorides.