Synthesis and bioactivity of N-cyclopropanecarboxyl-N′-pyridin-2-yl thiourea derivatives and related fused ring compounds

Cyclopropanecarboxylic acid or 2,2-dimethyl cyclopropanecarboxylic acid was used as a leading compound for its biological activity.Six new N-(substituted) cyclopropanecarboxyl-N′-pyridin-2-yl thioureas were prepared.Compound 5 was obtained by oxidizing cyclization of compound 4 in the presence of bromine in chloroform solution.The structures of 4 and 5 were confirmed by ~1H NMR and elemental analysis.The preliminary biological tests indicate that compound 4b and 4e have excellent herbicidal activity,and ...     

Generation of α-Boryl Radicals and Their Conjugate Addition to Enones: Transition-Metal-Free Alkylation of gem-Diborylalkanes

A transition-metal-free method for the alkylation of gem-diborylalkanes with α,β-unsaturated ketones has been developed. It is demonstrated that the α-boryl radicals can be generated efficiently from gem-diborylalkanes with the aid of catechol and oxidants. The α-boryl radicals formed through such process can be engaged in conjugate addition reaction with α,β-unsaturated ketones. This transformation is a straightforward method for the synthesis of γ-borylketones.     

Detection of Trace Amounts of 8-Hydroxy-2′-Deoxyguanosine in Commercial 2′-Deoxyguanosine by Means of HPLC Analysis and Electrochemical Analysis

Abstract

A commercial sample of 2′-deoxyguanosine (dG) was submitted to reversed phase HPLC analysis. The column effluent was analyzed by UV detection set at 293 nm coupled to an electrochemical detector at 600 mV oxidation potential. When both detectors were set at their highest sensitivity, the UV detector did not show the presence of the 8-hydroxy-2′-deoxyguanosine but the electrochemical detector was capable of detecting this oxidatively modified 2′-deoxyguanosine. When planning in vitro experiments with 2′-deoxyguanosine in order to detect the oxidatively modified nucleoside it is necessary to assess the presence of this C8-hydroxylated derivative in the commercial product.     

Generation and bleaching of E′-centers induced in a-SiO2 by γ-irradiation

Radiation indicator as well as radiation shielding of extremely high dose have been proposed. Three different types of a-SiO₂ namely, G₁-xerogel, G₂-fused and G₃-natural silica were monitored by EPR before and after γ-irradiation. The E′-center has been used for EPR radiation characterization of a-SiO₂ with assuming that the signal intensity changes with γ-irradiation differently as those of other EPR signals do. Formation and decay of the E′-center are closely related with its precursor, diamagnetic oxygen vacancies. Gamma ray of large dose (500 kGy) creates oxygen vacancies giving up-and-down irradiation effects, which, therefore, might be useful for high dose radiation indicator (G₁) and radiation shielding (G₂ and G₃).     

Facile Synthesis of 2-(4-Hydroxybiphenyl-3-yl)-1H-indoles from Anilines and 5′-Bromo-2′-hydroxyacetophenone

2-Arylindoles are attractive scaffolds because they are found in many pharmacologically active molecules. In this study, we describe the facile synthesis of diverse 2-(2-hydroxyphenyl)-1H-indoles from anilines and 5′-bromo-2′-hydroxyacetophenone in two steps using palladium-catalyzed indole cyclization as a key reaction. The indole cyclization was primarily controlled by the substituent properties of anilines. Suzuki-coupling reactions of 2-(5′-bromo-2′-hydroxyphenyl)-1H-indoles with arylboronic acids provided the corresponding 2-(4-hydroxybiphenyl-3-yl)-1H-indoles in moderate yield.     

Synthesis and properties of N,N′-bis(1,3-indanedion-2-yl)imidazolium betaine

A method for the synthesis of a new type of onium derivative of 1,3-indanedione — N,N-bis(1,3-indanedion-2-yl)imidazolium betaine — by anhydride condensation of N-(1,3-indanedion-2-yl)-N-carboxymethylimidazolium betaine with phthalic anhydride was developed. The new substance is an acid and forms stable salts.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 771–774, June, 1991.     

Synthesis and Characterization of 4′-Bromomethyl-2-(N-trityl-1H-tetrazol-5-yl) Biphenyl

Biphenyl tetrazole ring is an important component of the Sartan family of novel drugs. 4′-Bromomethyl-2-(N-trityl-1H-tetrazol-5-yl)biphenyl was synthesized in this article from 4′-methyl-2-cyano-biphenyl through three steps. 4′-Methyl-2-cyano-biphenyl was reacted with azide ions with the help of ammonium chloride as catalyst in an autoclave with high conversion to afford the tetrazole compounds in 70.6% yield. After being protected by the trityl group with 92.6% yield, 4′-methyl-2-(N-trityl-1H-tetrazol-5-yl) biphenyl was brominated with N-bromosuccinimide (NBS) in cyclohexane with 2,2′-azo-isobutyronitrile (AIBN) acting as an initiator to provide the title compound in 83.8% yield.     

Synthesis of 5-substituted-3-[(2′S,3′S)-3′-hydroxy-2′-hydroxymethyltetrahydrofuran-3′-yl]-1,2,4-oxadiazoles and their epimers

5-Phenyl-3-[(2′R,3′S)-3′-hydroxy-2′-dimethoxymethyltetrahydrofuran-3′-yl]-1,2,4-oxadiazole 10a and its epimer 11a, 5-methyl-3-[(2′R,3′S)-3′-hydroxy-2′-dimethoxymethyltetrahydrofuran-3′-yl]-1,2,4-oxadiazole 10b and its epimer 11b were synthesized from cyanohydrin benzoates 8a, 9a and cyanohydrin acetates 8b, 9b, respectively, by treatment with hydroxylamine in methanol via intramolecular transacylation and subsequent cyclization of the corresponding amidoximes. Hydrolysis and reduction of the dimethoxymethyl groups in the above compounds gave the desired compounds 12a, 13a, 12b and 13b.     

Calorimetric study of 2′-methylacetophenone and 4′-methylacetophenone

Values of the condensed phase standard (p = 0.1 MPa) molar enthalpy of formation for 2′- and 4′-methylacetophenones were derived from the standard molar energies of combustion, in oxygen, at T = 298.15 K, measured by static bomb combustion calorimetry. The values of the standard molar enthalpy of vaporization, at T = 298.15 K, were measured by Calvet microcalorimetry. Combining these two values, the following enthalpies of formation in the gas phase, at T = 298.15 K, were then derived: 2′-methylacetophenone, –(115.7 ± 2.4) kJ · mol⁻¹, and 4′-methylacetophenone, –(122.6 ± 2.4) kJ · mol⁻¹. Substituent effects are discussed in terms of stability and compared with other similar compounds. The value of the standard molar enthalpy of formation for 3′-methylacetophenone was estimated from isomerization schemes.     

Synthesis and Structure Determination of (2S, 2′S)-3-Phenyl-2-(pyrrolidin-2′-yl)- propionic Acid

Abstract

Aβ²,β³-homoproline derivative, (2S, 2′S)-3-phenyl-2-(pyrrolidin-2′-yl)propionic acid, was synthesized starting from l-proline. After preparation of the (4S, 4aS)-4-benzyl-4a,5,6,7-tetrahydro-pyrrolo-[1,2-c]pyrimidine-1,3-dione under a mild condition, the absolute configuration of target compound was assigned using 2D H-H COSY and H-H NOESY technologies.     

Detection and quantification of 3,5,3′-triiodothyronine and 3,3′,5′-triiodothyronine by electrospray ionization tandem mass spectrometry

A novel and rapid method for identifying and quantifying 3,5,3'-triiodothyronine (T3) and 3,3',5'-triiodothyronine (rT3; reverse T3) has been introduced using electrospray ionization tandem mass spectrometry (ESI-MS/MS). MS(2) spectra in either negative ionization mode or positive ionization mode can be used to differentiate T3 and rT3. Quantification of the T3 and rT3 isomers under the negative ionization mode is also achieved without prior separation by HPLC.     

Molecular and crystal structure of (pyrazin-1-ium-1-yl)(perfluoropyridin-4-yl) and (4,4′-bipyridin-1-ium-1-yl)(perfluoropyridin-4-yl)amides

The single crystal X-ray diffraction study of (pyrazin-1-ium-1-yl)(perfluoropyridin-4-yl) and (4,4??-bipyridin)-1-ium-1-yl(perfluoropyridin-4-yl)amides is performed. In all cases, the N⁺-N^? bond length is less than that of the single N_planar.-N_planar. bond, but considerably more than that of the double N=N bond, which indicates a weak involvement of the N^? lone pair of the C₅NF₄N^? group in conjugation with pyrazine or bipyridine moieties. Quantum chemical calculations by DFT/(PBE/L1), B3LYP/L1, and RI-MP2/L1 methods provide the geometry of amides similar to the experimental one. Crystals of (pyrazin-1-ium-1-yl)(perfluoropyridin-4-yl)amide form stacks mainly through F-?? interactions. The stacks are joined in 3D architecture by weak C-H??N and C-H??F hydrogen bonds. In the case of (4,4??-bipyridin)-1-ium-1-yl(perfluoropyridin-4-yl)amide crystals, an essential role is played by the ?? stacking interactions of heteroaromatic rings.     

Isolable Anionic,Neutral and Cationic Radicals from Reactions of N,N′-Dimesityldiamidocarbene and Lewis Acids

B(C₆F₅)₃ undergoes nucleophilic attack by N,N′-dimesityldiamidocarbene (DAC) with fluoride transfer to the boron center, resulting in a new zwitterion ( 1 ). This B−F fluoride can be replaced or abstracted to give the corresponding hydride ( 2 ) or triflate ( 3 ) derivatives or the corresponding cation ( 4 ). These species are reduced with KC₈ or Cp₂Co to give isolable anionic and neutral radicals ( 5 – 8 ). Similarly, the [Ph₃C] cation undergoes nucleophilic attack by DAC resulting in the spontaneous formation of the radical cation ( 9 ).     

Microwave promoted one-pot synthesis of 3-(2′-amino-3′-cyano-4′-arylpyrid-6′-yl)coumarins

A facile procedure for the synthesis of 3-(2′-amino-3′-cyano-4′-arylpyrid-6′-yl)coumarins are being reported starting from 3- acetylcoumarin,aromatic aldehydes and malononitrile.The reactions were carded out on microwave irradiation in good yield with short time and easy work-up.The structures of all the compounds have been confirmed on the basis of their analytical,IR,~1H NMR, and mass spectral data.     

Synthesis and mesomorphic properties of 2-(4′-alkoxybiphenyl-4-yl)-1H-benzimidazole derivatives

Three series of 2-(4′-alkoxybiphenyl-4-yl)-1H-benzimidazole derivatives (nM-x), which possessed 5-nitrobenzimidazole (nM-N series), benzimidazole (nM-H series) or 5-methylbenzimidazole (nM-M series) units at the end of the molecule, were synthesised and characterised by infrared, ¹H- and ¹³C-nuclear magnetic resonance spectra, electrospray ionisation-mass spectrometry and elemental analysis. Their phase transition behaviour was investigated by differential scanning calorimetry, polarising optical microscopy and X-ray diffraction. All the compounds exhibited enantiotropic smectic mesophases with wide temperature domains for a carbon number in the alkoxy chain from 6 to 16, where the mesophase ranges were 14–91°C and 17–99°C during heating and cooling processes for the nM-N compounds, 7–25°C and 8–49°C for the nM-H compounds and 48–81°C and 52–85°C for the nM-M compounds, respectively. The effect of the length of alkoxy chain on mesomorphic properties was discussed. The nM-N and nM-M exhibited a much wider mesophase range whether during heating or cooling process than the corresponding nM-H series, especially for the longer terminal chain (n > 8), which indicated that the substituent in the benzimidazole moiety was helpful in increasing the mesophase stability.     

Generation of cytidine 5′-triphosphate using adenylate kinase

A membrane-enclosed enzyme reactor containing adenylate kinase (E.C. 2.7.4.3, rabbit muscle) and pyruvate kinase (E.C. 2.7.1.40) converts cytidine 5′-monophosphate (CMP) and phosphoenolpyruvate (PEP) to cytidine 5′-triphosphate (CTP) and pyruvate on a gram scale.     

Synthesis and properties of ruthenium(II) complexes of 3,3′-polymethylene-2-(pyrid-2′-yl)benzo[b]-1,10-phenanthrolines

Coordination abilities of unsymmetrical tridentate ligands, 3,3′-polymethylene-2-(pyrid-2′-yl)-benzo[b]-1,10-phenanthrolines (4) were studied. Reactions of the 3,3′-di- and 3,3′-trimethylene-2-(pyrid-2′-yl)benzo[b]-1,10-phenanthrolines (4b and 4c) with RuCl₃ ? 3H₂O afforded [Ru(4b)₂]²⁺ and [Ru(4c)₂]²⁺ in 57% and 78% yield, respectively, while reactions of the parent non-bridged ligand (4a), tetramethylene-bridged ligand (4d), and fully aromatized ligand (4e) afforded a messy mixture. Reactions of 4 with Ru(tpy)Cl₃ (tpy = 2,2′;6′,2″-terpyridine) afforded [Ru(tpy)(4)]²⁺ in 61–72% yields. UV absorption spectra of the ligands showed four ligand-centered (LC) π–π* transitions and their Ru complexes showed four LC π–π* transitions and one Ru(d_π) → ligand(π*) MLCT. The ligands showed three major emission maxima (λ _emission) in the region of 393–418, 416–445, and 437–471 nm in which λ _emission is highly dependent on the length of the methylene bridge connecting C3 of benzo[b]-1,10-phenanthroline and C3 of pyridine. Ru complexes with fully aromatic ligand, [Ru(tpy)(4e)]²⁺, and the most distorted ligand, [Ru(tpy)(4d)]²⁺, showed two emission maxima at 410 and 444–446 nm, while the others showed one emission at 410 nm. Each of the emission maxima is bathochromatically shifted from the complex with the most distorted ligand (4d) to the complex with fully aromatized planar ligand (4e) indicating lower energy emission.