Synthesis and Biological Screening of Novel Thiadiazoles,Selenadiazoles, and Spirocyclic Benzopyran by Ultrasonic and Microwave Irradiation

We describe the synthesis of novel thiadiazole, selenadiazole, and spirocyclic benzopyrans via the semicarbazides 3 and thiosemicarbazides 3 of 2-ethyl-2-methyl-4H-chromen-4-ones 1 by conventional and nonconventional methods. The microwave and ultrasonic irradiation methods form the respective products in excellent yields in very short reaction time as compared to the conventional method. The synthesized compounds were tested for antimicrobial screening against bacteria and fungi show moderate activity.

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Theoretical Calculations and Experimental Verification of the Antibacterial Potential of Some Monocyclic β-Lactams Containing Two Synergetic Buried Antibacterial Pharmacophore Sites

A new series of N-thiazole, 3-phenyl, 4-substituted phenyl azetidine-2-ones 4(a–h) have been synthesized in good yields starting from 2-aminothiazole 1. In the first step, then Schiff's bases 3(a–h) are prepared by the condensation of 2-aminothiazole 1 with different aryl aldehydes 2(a–h). Finally, monocyclic β-lactams, i.e. substituted azetidinones 4(a–h), were the products formed using three different methods by the dehydrative cyclocondensation of 3(a–h) with phenyl acetyl chloride in dioxane, phenyl acetic acid–thionyl chloride in dichloromethane and phenyl acetic acid–phosphorus oxychloride in dichloromethane in the presence of triethylamine. We found that latter method is the best as compared with the former two methods. The synthesized molecules 4(a–h) were screened for their antibacterial activity against four microorganisms: Staphylococcus aureus (Gram positive), Pseudomonas vulgaris (Gram positive), Pseudomonas aeruginosa (Gram negative), and Escherichia coli (Gram negative). Their antibacterial activities are reported, and on the basis of the screening data available, attempt is also made to elucidate the structure–activity relationship.

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Efficiency of Five Chromatographic Systems for the Separation of Casein Digest

Abstract

Different chromatographic methods and packing supports have been proposed for the separation of protein hydrolysates. The selection of a method is often based on available equipment and quantity of sample and disposal time. Five liquid chromatographic systems were compared on the basis of their capability to resolve casein digest versus length of time and capacity.     

Towards a Standard Method for the Measurement of Organic Carbon in Sediments

Abstract

The precisions achieved by two different methods for analysis of organic carbon in soils and sediments were determined and compared. The first method is a rapid dichromate oxidation technique (Walkley-Black) that has long been a standard in soil chemistry. The second is an automated coulometric titration method for which commercial instrumentation is available. The latter method shows relative standard deviations that are six to twenty times smaller than the dichromate oxidation technique. Development of a standardized sediment with a low level of organic carbon is recommended in order to facilitate the evaluation of the precision and accuracy of organic carbon measurement techniques.     

Simulation of 1-Aminopropanephosphonic Acids with Consideration of Aqueous Solutions

Abstract

While solid state structures of aminophosphonic acids are well characterised by X-Ray methods only few informations are available concerning the solution state structures. We have attempted to simulate the structures of acids and corresponding cations and anions in aqueous solutions. It proved to be difficult to describe correctly the electrostatic interactions of solute and solvent by theoretical methods.     

New method for the synthesis of 4-aryl-3,4-dihydro-2H-benzo[g]chromene-2,5,10-triones

Abstract

We report herein a new method for the synthesis of 4-aryl-3,4-dihydro-2H-benzo[g]chromene-2,5,10-triones 4 that proceeds in good yields (74–86%) and mild reaction conditions between readily available 2-amino-4-aryl-5,10-dioxo-5,10-dihydro-4H-benzo[g]chromene-3-carbonitriles 1, and formic acid (88%), at reflux for 6?h. In addition, we have also studied the antioxidant activities using DPPH and total TAC methods.     

Reverse-Phase High Performance Liquid Chromatographic Determination of Clidinium Bromide and Chlordiazepoxide in Tablet Formulations

Abstract

Clidinium bromide is a quaternary ammonium anticholinergic agent with peripheral effects. It is commercially available in combination with chlordiazepoxide. There is no official compendial method available for the analysis of both compounds concurrently. Conventional methods for determining both compounds involve extensive extraction and thus are time-consuming, and lack precision. The analytical scheme described in this paper provides a fast and reliable reverse-phase HPLC for chlordiazepoxide and clidinium bromide in pharmaceutical combinations. The mobile phase was 0.04 M ammonium acetate in 70% acetonitrile solution with 1% dimethylformamide (pH 6). The column was microPak MCH-10 (300.0 mm × 4.0 mm), UV detection at 254 nm and benzophenone was used as internal standard. The method was confirmed for linearity, recovery, specificity, accuracy, and applicability.     

State Of The Art For The Examination Of Uv Spectra Of Waters And Wastewaters

Abstract

The paper reviews different mathematical methods for the exploitation of the UV spectrum of waters and wastewaters, including the interferences treatment. After the presentation of simple methods and their limits, several global approaches using a matricial presentation of the data are discussed. The usual methods, statistical multivariate or deterministical procedures are not relevant. Nevertheless, other methods based on the restitution of interferences effect as a combination of fixed basic signals, either mathematical or physical, are available. The first procedure is semi-deterministic without chemical knowledge of the interferences nature or effects-and only mathematical hypothesis on the spectrum shape-while the second is a more qualitative method based on the fact that most of interferences can be resumed as a linear combination of few independent spectra with chemical signification. These considerations underline the importance of direct examination of UV spectra of waters and wastewaters.     

Kinetic Resolution of Cyclic Sulfoxides by Enzyme Promoted Hydrolysis of 2-Alkoxycarbonyl-3,6-Dihydro-2H-Thiapyran-1-Oxides

Abstract

Among many methods of preparation of optically active sulfoxides, those applying enzymes are becoming more and more popular¹. In continuation of our recent investigations on the enzyme promoted hydrolysis of sulfinyldicarboxylates² we turned our attention to cyclic six-membered sulfoxides 1. These compounds are easily available by the cycloaddition reaction of butadienes with appropriate sulfines obtained in situ from the corresponding esters (or their O-silyl enolethers) with thionyl chloride in the presence of a base³. Three compounds shown in the scheme were chosen for our investigations. It should be noted that compounds lb and lc are obtained as single diastereoisomers.     

Synthesis and Antibacterial Activity of Some New Derivatives of Thiosemicarbazide and 1,2,4-Triazole

Abstract

In a reaction of hydrazides of cyclohexylacetic acid 1 and phenylacetic acid 2 with isothiocyanates, respective thiosemicarbazide derivatives 3–18 were obtained. Further cyclization with 2% NaOH led to the formation of 5-(cyclohexylmethyl/benzyl)-4-substituted-2,4-dihydro-3H-1,2,4-triazole-3-thiones 19–34. Structures of all new products were confirmed by analytical and spectroscopic methods. All compounds were screened for their in vitro activity against some species of bacteria and fungi.

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New and Practical Synthesis of Montelukast Sodium,an Antiasthmatic Drug

Abstract

A new and practical synthesis of montelukast sodium, an antiasthmatic drug, is described. The key steps are the synthesis of nitrile derivative 4 by chiral reduction of keto ester 9 using (?)-DIP-Cl, synthesis of vinylquinoline framework 16 by Wittig reaction, and Heck coupling of nitrile 4 with vinylquinoline 16. The method is operationally simple and suitable for the industrial production of the drug substance.

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The ONN-complexes of dioxomolybdenum(VI) with dibasic 2-hydroxy-1-naphthaldehyde<Emphasis Type="Italic"> S</Emphasis>-methyl/allyl-4-phenyl-thiosemicarbazones

New dioxomolybdenum(VI) complexes were prepared by reacting S-methyl/allyl-4-phenyl-thiosemicarbazones of 2-hydroxy-1-naphthaldehyde (L ¹ H₂ and L ² H₂) and [MoO₂(acac)₂] in methyl, ethyl and propylalcohols. In the complexes the doubly deprotonated ligands are coordinated to molybdenum as tridentate ONN-donors through phenolic-oxygen, azomethine- and thioamide-nitrogen. The solid complexes of general formula [MoO₂L(ROH)] which contain an alcohol (ROH) as second ligand were characterized by physico-chemical and spectroscopic methods. The fluorescence emission intensities of the compounds were recorded in chloroform, and the intensity changes were evaluated depending on chelation and time. The structure of the S-allyl-4-phenyl-thiosemicarbazone complex has been determined by the single crystal X-ray diffraction method. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

A General Method for the Synthesis of N,N-Dialkylaminobutylamines

A general method for the synthesis of N,N-dialkylaminobutylamines 4 from readily available chloroacetamides 6 is described.     

New Routes to β-Iminophosphonates,Phosphineoxides, and Sulfides

Abstract

Two synthetic methods leading to β-iminophosphonates, phosphineoxides, and sulfides 2 are reported. The first method involves the reaction of imines with chlorophosphines and phosphites followed by oxidation or sulfurization. The second one utilizes the reaction of imines with diethylchlorophosphate and thiophosphate. The stereochemistry of the obtained products is discussed, and their structure is confirmed by NMR (¹H, ³¹P, ¹³C) and IR spectroscopies, and by mass spectrometry.

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GRAPHICAL ABSTRACT      

Conformational Behaviors of 2-Substituted Cyclohexanone Oximes: An AB Initio,Hybrid Dft Study,and NBO Interpretation

Abstract

The impacts of the generalized anomeric effect (GAE) and gauche effect (GE) associated with donor–acceptor electron delocalizations and dipole–dipole interactions on the conformational properties of 2-methoxy- (1), 2-methylthio- (2), 2-methylseleno- (3), 2-fluoro- (4), 2-chloro- (5), and 2-bromocyclohexanone oxime (6) have been studied by means of hybrid density functional theory (B3LYP/6–311+G**) and ab initio molecular orbital (HF/6–311+G**)-based methods and natural bond orbital (NBO) interpretation. Both methods used showed that the above compounds exist predominantly in the axial chair conformation and the axial conformation stability increased from 2-methoxy- (1) to 2-methylselenocyclohexanone oxime (3) and also from 2-fluoro- (4) to 2-bromocyclohexanone oxime (6). The NBO analysis showed that the GAE increases from compound 1 to compound 3 and also from compound 4 to compound 6. GE does not have significant impact on the conformational behaviors of compounds 1–6 and GAE succeeds in accounting qualitatively for the increase of the axial preferences in both series of compounds.

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Supporting Information Available. The structures optimized and thermodynamic functions of the axial and equatorial conformations of compounds 1–6. This material is available free of charge via the Internet.     

Synthesis of Trifunctional Bis-azide Photoaffinity Probe

Methyl 3-azidomethyl-5-azido-benzoate (1b) and its corresponding hydroxymethyl reduction product (1a) have been utilized for the synthesis of valuable nonradioactive photoaffinity probes. Previous preparations of (1a) depend upon a nonselective monoactivation of a bis-1,3-hydroxymethylaryl intermediate, leading to the expected statistical range of products/starting material. We report an alternate synthetic approach to these 1,3,5-trisubstituted molecules using recently described C-H activation and boronate refunctionalization methods.

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Simple UV and visible spectrophotometric methods for the determination of doxycycline hyclate in pharmaceuticals

Doxycycline hyclate (DOX), a broad spectrum antibiotic with activity against a wide range of gram-positive and gram-negative bacteria, is widely used as a pharmacological agent and as an effector molecule in inducible gene expression system. Three simple, selective, rapid, accurate, precise and cost-effective spectrophotometric methods for the determination of DOX in bulk drug and in tablets have been developed and validated. First method (method A) is based on the measurement of absorbance of DOX in 0.1 M HCl at 240 nm. The second method (method B) is based on the measurement of yellow chromogen at 375 nm which is formed in 0.1 M NaOH. The third method is based on the measurement of 2: 1 complex formed between DOX and iron(III) in H₂SO₄ medium, the complex peaking at 420 nm (method C). The optimum conditions for all the three methods are optimized. Beer’s law was obeyed over the ranges 2.5–50.0, 1.50–30.0 and 10–100 g/mL for method A, method B and method C, respectively. The apparent molar absorptivity values are calculated to be 1.03 × 10⁴, 1.73 × 10⁴, and 5.21 × 10³ L mol⁻¹ cm⁻¹ for method A, method B, and method C, respectively. The Sandell sensitivity, limit of detection (LOD) and limit quantification (LOQ) values are also reported. All the methods were validated in accordance with current ICH guidelines. The developed methods were employed with high degree of precision and accuracy for the estimation of total drug content in commercial tablet formulations of DOX.     

Green approaches for the synthesis of nucleotides,their conjugates and analogues

Abstract

We have developed original one-pot and protecting group-free approaches, which are also user-friendly and reliable, to synthesize nucleotides and derivatives starting from nucleoside 5’-monophosphates. Both methods present convenient set-up, i.e., non-dry solvents and reagents, substrates in their sodium or acid form, and commercially available and cheap phosphorus reagents as sodium and potassium salts.     

Fugacity Calculations Using Estimated Physicochemical Properties

Abstract

Fugacity calculations according to Mackay and Paterson have been performed for a set of 114 chemicals. Calculations using experimental input parameters and calculations based on estimated parameters are comparatively presented. It is shown that estimated parameters are useful for an estimation of environmental distribution provided the estimation methods are chosen carefully and experimental melting points as well as boiling points are available. Estimation methods for vapour pressure and water solubility need further development.     

One-Pot,Facile, Highly Efficient,and Green Synthesis of Acridinedione Derivatives Using Vitamin B1

An efficient methodology for the synthesis of acridinedione derivatives 4a–o has been achieved by one-pot, multicomponent condensation of dimedone 1, various amines 2a–d, and substitute aromatic aldehydes 3a–k, in the presence of the easily available, inexpensive, and nontoxic catalyst vitamin B₁ (VB₁) as a versatile biodegradable. Synthesis of acridine-type compounds was performed in good yields in water as green solvent. Its high-yield efficiency; clean, ecofriendly, simple workup procedure; and easy purification are regarded as the main advantages of this method besides its green solvent. The synthesized compounds are characterized using spectroscopic analyses (FTIR, ¹H NMR, ¹³C NMR, and high-resolution mass spectrometry) techniques.