超声辐射下合成4,5-二氢-1-取代胺亚甲基-3-(2-三氟甲基苯并[d]咪唑- 1-亚甲基)-4-芳基-1,2,4-三唑-5-硫酮

以1-肼羰亚甲基-2-三氟甲基苯并[d]咪唑(1)为原料, 与芳基异硫氰酸酯在无水乙醇中反应得酰氨基硫脲2a～2d, 继而在氢氧化钠水溶液中合环得4,5-二氢-3-(2-三氟甲基苯并[d]咪唑-1-亚甲基)-4-芳基-1,2,4-三唑-5-硫酮(3a～3d), 然后分别采用超声辐射法和常规加热法与四种胺反应合成了16个未见报道的Mannich碱4a～4d, 5a～5d, 6a～6d和7a～7d. 与常规加热法对比, 超声辐射法具有操作简单, 反应时间短, 条件温和, 产率高, 副反应少等优点, 为此类化合物的合成提供了一种有效的新方法. 目标化合物的结构经元素分析, IR和¹H NMR确证.     

A Rapid Spectrophotometric Method to Resolve Ternary Mixtures of Propyphenazone, Caffeine, and Acetaminophen in Tablets

 A simple and rapid derivative spectrophotometric assay procedure is described for the analysis of caffeine (1), acetaminophen (2), and propyphenazone (3) in tablet formulations. The concentration range of application is 5.0–25.0 μg·cm⁻³ for 2 and 3 and 1.0–5.0 μg·cm⁻³ for 1. The method involves the extraction of the drugs from tablets with 0.1 N H₂SO₄, filtration, appropriate dilution, and measurement of the fourth derivative absorbance values at zero crossing wavelengths of 230.0, 263.2, and 256.6 nm for 1, 2, and 3. As a reference method, a reversed phase HPLC procedure was developed. Commercially available tablets were analyzed; statistical comparison of the results with those obtained from the reference method showed good agreement. The derivative spectrophotometric method has the advantage of being simple, rapid, inexpensive, and easy to perform.     

A Rapid Spectrophotometric Method to Resolve Ternary Mixtures of Propyphenazone, Caffeine, and Acetaminophen in Tablets

Summary.  A simple and rapid derivative spectrophotometric assay procedure is described for the analysis of caffeine (1), acetaminophen (2), and propyphenazone (3) in tablet formulations. The concentration range of application is 5.0–25.0 μg·cm⁻³ for 2 and 3 and 1.0–5.0 μg·cm⁻³ for 1. The method involves the extraction of the drugs from tablets with 0.1 N H₂SO₄, filtration, appropriate dilution, and measurement of the fourth derivative absorbance values at zero crossing wavelengths of 230.0, 263.2, and 256.6 nm for 1, 2, and 3. As a reference method, a reversed phase HPLC procedure was developed. Commercially available tablets were analyzed; statistical comparison of the results with those obtained from the reference method showed good agreement. The derivative spectrophotometric method has the advantage of being simple, rapid, inexpensive, and easy to perform. Received April 18, 2001. Accepted (revised) June 5, 2001     

O-H bond dissociation energies in hydroquinones and 4-hydroxyphenoxyl radicals and effect of solvation on the kinetics of reactions involving hydroquinones and semiquinone radicals

The O-H bond dissociation energies (D _OH) in the molecules of 2,5-dimethylhydroquinone (1) and 2,5-di-tert-butylhydroquinone (2) and in the corresponding semiquinone radicals (5 and 8, respectively) were estimated by the method of intersecting parabolas (IP) from experimental data on the rate constants for the reactions of these compounds with N-phenyl-1,4-benzoquinonemonoimine (3) and using the density functional B3LYP/6-31+G* quantum chemical calculations. When calculating the D _OH values by the IP method, solvation of reactants and transition states should be taken into account. The energies of solvation of quinones, semiquinone radicals, and hydroquinones were evaluated by the PCM method. The results of quantum chemical calculations obtained with inclusion of the effects of solvation and the D _OH estimates obtained by the IP method are in good agreement, being equal to 337.9±1.6, 242.5±1.4, and 242.7±3.4 kJ mol⁻¹ for molecule 1 and radicals 5 and 8, respectively. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2244–2251, October, 2005.     

Stability Indicating Hplc Method for the Determination of Sparfloxacin (Spar)

ABSTRACT

A rapid, sensitive and stability indicating method for the determination of sparfloxacin (SPAR) by RP - HPLC has been developed on a Merck RP - Select B (5 μm; 12.5 cm x 4.0 mm) column using a mobile phase of water: acetonitrile: triethylamine (80 : 20 : 0.2 v/v) pH of which was adjusted to 2.6 with orthrophosphoric acid. The flow rate was 1 ml / min. and the detection was carried out at 304 nm using Waters 486 variable wavelength detector. The retention time for SPAR was 7.2 min. Linearity range was from 8 - 1000 ppm. The method showed good precision and accuracy when applied to two brands of tablets containing SPAR. In alkaline media SPAR is stable where as it undergoes degradation in acidic and oxidising conditions generating different degradation products the nature of which is required to be established. The proposed method nicely separates the degraded products from SPAR and hence can be used as stability indicating method for the assay of SPAR.     

HPLC simultaneous determination of arbutin,chlorogenic acid and 6′-O-caffeoylarbutin in different parts of Vaccinium dunalianum Wight

Arbutin (1), chlorogenic acid (2) and 6′-O-caffeoylarbutin (3) are three major components in Vaccinium dunalianum Wight with various promising bioactivities. A reliable, reproducible and accurate method for simultaneous and quantitative determination of 1–3 is developed by RP-HPLC analysis. This method should be appropriate for the quality assurance of unprocessed and processed materials of V. dunalianum. The contents of 1–3 in different parts of V. dunalianum from different origins were analysed. The content of 3 was much higher than those of 1 and 2, accounting for up to 31.76% in the dried leaf buds. Moreover, the leaf buds, flower buds and leaves showed a tendency towards higher contents of 1–3 than the other plant parts.     

Thermodynamic properties of glycolic acid and glycolide

The values of combustion and formation enthalpy for glycolic acid (I) and glycolide (II) were determined by calorimetry. The temperature dependence of vapor pressures of I and II was obtained using the transpiration method, and the sublimation enthalpies were obtained. The enthalpy of melting of I was found by differential scanning calorimetry. Stable conformers were determined by the ab initio (DFT) method, and combinations of the fundamental oscillations and inertia momenta of I and II conformers were calculated. The full and relative energies of the compounds most stable conformers were found by a composite G3MP2 method, and the enthalpies of formation of I and II in the gaseous state were estimated. The values of the thermodynamic properties in the ideal gas state were determined over the range of 0–1500 K. A thermodynamic analysis was performed for the process of preparation of II from I and the formation of polyglycolide (III) from I and II.     

Cu(II), Ni(II), and Hg(II) thiocyanate complexes incorporating 4,5-diazafluoren-9-one: synthesis,spectroscopic characterization,X-ray studies,and magnetic properties

This article presents a combined experimental and computational study of the complexes [Cu(dafone)₂(SCN)₂] (1), [Ni(dafone)₂(SCN)₂] (2) and [Hg(dafone)(SCN)₂] (3), where dafone stands for 4,5-diazafluoren-9-one. The compounds have been studied by IR, UV–Vis spectroscopy, and single crystal X-ray diffraction. The electronic structures of these complexes have been calculated with the density functional theory (DFT) method. The spin-allowed electronic transitions of 1, 2, and 3 have been calculated with the time-dependent DFT method, and their UV–Vis spectra have been discussed on this basis.     

A comparative study of Mentha arvensis L. and Mentha haplocalyx Briq. by HPLC

We have developed a new method to simultaneously determine five marker compounds in Menthae Herba via HPLC/PDA – including hesperidin (1), rosmarinic acid (2), diosmin (3), didymin (4) and buddleoside (5). The newly developed method was successfully used to analyse for two species (Mentha arvensis L. and Mentha haplocalyx Briq.) of Menthae Herba, and the satisfactory results were obtained from the validation of developed method. The pattern analysis could greatly discriminate between M. arvensis L. and M. haplocalyx Briq. In conclusion, the proposed HPLC/PDA method is suitable for quality evaluation of Menthae Herba.     

Efficient Synthesis of 2‐Aminothiazole‐4‐phenyl‐5‐acetamides via the Open Chain Tautomers of γ‐Keto Amides

A simple and efficient method is described for the synthesis of new functionalized 2‐aminothiazoles, the 2‐aminothiazole‐4‐phenyl‐5‐acetamides 5, in 67–96% yields based on an application of the Hantzsch synthesis. The method involves the reaction of thiourea with 3‐benzoyl‐3‐bromo‐propionamides 4 prepared from the corresponding 3‐benzoylpropionamides 3. The tautomeric structure of the γ‐keto amides 3 and 6 is directly related to the present study, because 2‐aminothiazoles 5 are readily obtained from the corresponding open chain γ‐keto amides 3.     

Spectrophotometric determination of methimazole,D-penicillamine,captopril, and disulfiram in pure form and drug formulations

A spectrophotometric method for the determination of methimazole (MT), D-penicillamine (PA), captopril (CA), and disulfiram (DM) was proposed. The method is based on the reaction of sulfur compound with N,N-dimethyl-p-phenylenediamine (DMPD) in acidic solution, in the presence of Fe³⁺ ions as oxidizing agent. The Beer’s law was obeyed in the range 16–110 mg of MT, 19–260 mg of PA, 29–160 mg of CA, and 36–110 mg of DM. The method was successfully applied to the quantification of these compounds in pharmaceuticals.     

Ozonization: An Efficient Method for the Oxidation of Halophosphines

Abstract

The ozonization of various halophosphines 1a-j leads with quantitative yields to the corresponding phosphine oxides 2a-j.

Ozonization is a convenient method of oxidation, in particular of compounds with bulky ligands (1c, 1d, 1e).     

Efficient and Convenient Method for Synthesis of Benzofuran-3-acetic Acids and Naphthafuran-acetic Acids

Herein, we report an efficient and convenient method for synthesis of benzofuran-3-acetic acids and naphthafuran-acetic acids 5a–p by the reaction of substituted-4-bromomethylcoumarins with aqueous sodium hydroxide at refluxing temperature. The obtained products are characterized by infrared, ¹H NMR, ¹³C NMR, and mass spectral data. Structures 5a and 5e are confirmed by their single x-ray diffraction studies. The advantages of this method are good yields, easy workup, and no chromatographic purifications.     

一步合成1,3,4-三芳基取代3,4,5,6-四氢嘧啶-2(1H)-酮衍生物

以芳基异氰酸酯(1)和β-芳胺基苯丙酮(2)为原料, 甲苯为溶剂, 在回流条件下一步有效地合成了1,3,4-三芳基取代3,4,5,6-四氢嘧啶-2(1H)-酮类化合物3, 并研究了反应条件对产率的影响. 结果表明, 该法具有操作简单、原料易得、反应收率高(79～96%)等优点.     

1-(Phenylsulfonyl)indol-2-yl Triflate: A Versatile Reagent for the Synthesis of 2-Substituted Indoles

The palladium-catalysed reaction of 1-(phenylsulfonyl)indol-2-yl triflate 1, with a variety of aryl and heteroaryl boronic acids 2 or vinyl tributylstannane 3 provides a general and an efficient method for the synthesis of 2-substituted indoles 4.     

Novel pyrimidine derivatives by sonication and traditional thermal methods

Abstract

A series of bis-compounds (2) were synthesized by condensing dihydro-1,3-(disubstituted)phenyl-2-thioxopyrimidine-4,6(1H,5H)-dione with hippuric acid in presence of acetic anhydride. The compound (2) on further treatment with aromatic amine afforded dihydropyrimidine (3) through an eco-friendly procedure by sonication. The sonication method reduces time and gives higher yields, and also the effluent produced is free from hazardous contamination and organic by-products. The novel pyrimidines were also synthesized by traditional methods for comparison purposes and sonication method was found to be superior. Structures of the synthesized compounds have been elucidated on the basis of elemental analysis and spectral data.     

A NOVEL SYNTHETIC APPROACH TO 4-SUBSTITUTED QUINAZOLINES

Abstract

A novel two-step synthetic method to prepare 4-(thienyl)quinazolines (8a and 8b) is described. The method is based on the simultaneous reductive cyclization of a nitro group β to the carbonyl group in ketones under Leuckart reaction conditions. The method has been found useful for the syntheses of the 4-substituted quinazolines.     

Synthesis,structure, and NMR spectra of a new ferrocenylbenzene tricarbonylchromium complex

Complex 1 (1,2,4-triferrocenylbenzene tricarbonylchromium), possessing four heterometals, has been synthesized efficiently by a new method in one pot. Through detailed study on the NMR chemical shifts of 1 and the ligand 2, the NMR chemical shifts of 1 shift upfield from those of 2. The NMR spectra of 1 have reduced magnetic anisotropy of benzene after Cr(CO)₃ coordination with 2. The ferrocenyl groups have electron donating effect on the central benzene ring of 1.     

VERSATILE SYNTHESIS AND FUNGICIDAL ACTIVITIES OF 6-AMINO-3- ALKYLTHIO-1,5-DIHYDRO-1-PHENYL-PYRAZOLO [3,4-D]PYRIMIDIN-4-ONE DERIVATIVES

A series of new 6-alkylamino-3-alkylthio-1-phenyl-1H-pyrazolo[3,4-d] pyrimidin-4(5H)-one derivatives 5 and 6 have been rapidly synthesized by a novel solution-phase regioselective synthetic method. Treatment of pyrazole o-aminoester 1 with dibromotriphenylphosphorane gave iminophosphorane 2, which underwent a aza-Wittig reaction with phenyl ioscyanate to provide the carbodiimide 3. The latter intermediate reacted with alkylamines and regioselectively provided the 1,5-dihydro-pyrazolo[3,4-d]pyrimidin-4-one derivatives 5 and 6, some of which exhibited good fungicidal activity.     

A new triterpenoid saponin from Pulsatilla cernua predicted by NMR-based mosaic method

Abstract

A saponin (1) with gypsogenin as aglycone was isolated from the roots of Pulsatilla cernua. The aglycone of compound 1 was considered as gypsogenin which was rarely found in this genus. Its structure was predicted by NMR-based “mosaic” method rapidly, and further confirmed on the basis of spectroscopic data, including 2D NMR spectra and chemical evidence. This work suggested that NMR-based mosaic method is suitable for most of saponins from common species of genus Pulsatilla.