bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis of Some New 4,5-Substituted-4H-1,2,4-triazole-3-thiol Derivatives
Authors: Koparır M. , Cansız A. , Demirdağ A.
Published: October 2008

In this study appropriate hydrazide compounds, furan-2-carboxylic acidhydrazide (1) and phenylacetic acid hydrazide (2) were converted into 1,4-substitutedthiosemicarbazides 4a-e and 5a-e and 4-amino-5-(furan-2-yl or benzyl)-4H-1,2,4-triazole-3-thiols 7 and 10. The 1,4-substituted thiosemicarbazides were then converted into5-(furan-2-yl or benzyl)-4-(aryl)-4H-1,2,4-triazole-3-thiols 8a-e and 9a-e. In addition, theazomethines 11a-d and 12a-d were prepared from the corresponding arylaldehydes and the4-amino-5-(furan-2-yl or benzyl)-4H-1,2,4-triazole-3-thiols 7 and 10. The structures of allthe synthesized compounds were confirmed by elemental analyses, IR, 1H-NMR and13 C-NMR spectra.
Structure-Acidity-IR Spectra Correlations for p-Substituted N-Phenylsulfonylbenzamides†
Authors: Perjessy Alexander , Fabian Walter M.F. , Parik Patrik , Ludwig Miroslav , Loos Dusan , Sustekova Zora
Published: October 2008

The wavenumbers of the IR absorption bands of the C=O, S=O and N-H stretching vibrations for a series of p-substituted N-phenylsulfonylbenzamides were measured in trichloromethane. The bond orders, Mulliken charges, charge densities and heats of formation were calculated using the PM3 method. Fifty significant mutual mono parameter (MP) and six dual parameter (DP) correlations were found for the IR spectral, theoretical structural data, substituent constants and previously reported dissociation constants in five polar organic solvents. The transmission of the substituent effects has been discussed and the solvent effect on the slopes of some linear correlations was evaluated using different solvent parameters. The results showed that the factors describing the electronic structure and controlling the dissociation equilibrium and the IR spectra properties of p-substituted N-phenylsulfonylbenzamides must be the same
Synthesis and Some Reactions of 3-Chloro-2-(cyanomethylene)-1,2-dihydroquinoxalines
Authors: Obafemi Craig A. , Pfleiderer Wolfgang
Published: October 2008

2,3-Dichloroquinoxaline and some of its derivatives have been reacted with malononitrile and ethyl cyanoacetate to yield a variety of 3-chloro-2-(cyanomethylene)- 1,2-dihydroquinoxaline derivatives. The reaction of 3-chloro-2-(dicyanomethylene)-1,2- dihydroquinoxaline (2e) with pyridine and its methyl derivatives led to the zwitterionic structures 6a-6c. The structures of the newly synthesized compounds were assigned by spectroscopic data and elemental analyses.
Synthesis and Determination of pKa Values of Some New 3,4-Disubstituted-4,5-Dihydro-1H-1,2,4-triazol-5-one Derivatives in Non-aqueous Solvents
Authors: Yüksek Haydar , Ocak Zafer , Alkan Muzaffer , Bahçeci Sule , Özdemir Mustafa
Published: October 2008

3-Alkyl(Aryl)-4-amino-4,5-dihydro-1H-1,2,4-triazol-5-ones (2) reacted with 2-furoyl chloride and thiophene-2-carbonyl chloride to afford the corresponding 3- alkyl(aryl)-4-(2-furoylamino)-4,5-dihydro-1H-1,2,4-triazol-5-ones (3) and 3-alkyl(aryl)- 4-(2-thienylcarbonylamino)-4,5-dihydro-1H-1,2,4-triazol-5-ones (4), respectively. The new compounds synthesized were characterized by using IR, 1H-NMR, 13C-NMR and UV spectral data together with elemental analysis. In addition, to investigate the effects of solvents and molecular structure upon acidity, compounds 3 and 4 were titrated potentiometrically with tetrabutylammonium hydroxide in four non-aqueous solvents (isopropyl alcohol, tert-butyl alcohol, N,N-dimethylformamide and acetonitrile). The half-neutralization potential values and the corresponding pKa values were determined for all cases.
Reactions of Substituted Furan-2-carboxaldehydes and Furo[b]pyrrole Type Aldehydes with Benzothiazolium Salts
Authors: Puterová Zita , Krutošíková Alžbeta , Lyčka Antonín , Ďurčeková Tatiana
Published: October 2008

A series of new push-pull compounds were synthesised by reaction of 5-aryl- furan-2-carboxaldehydes and furo[b]pyrrole type aldehydes with benzothiazolium salts. These new condensation products represent highly conjugated systems that have potential biological activity. The reaction of furo[b]pyrrole type aldehydes with benzothiazolium salts give potential precursors of cyanine dyes.
Preparation of New 2,3-Diphenylpropenoic Acid Esters – Good Yields Even for the More Hindered Z Isomers
Authors: Boros László , Felföldi Károly , Pálinkó István
Published: October 2008

The potassium salt of E- and Z-2,3-diphenylpropenoic acids prepared in situ could be esterified efficiently in DMSO with the appropriate alkyl halides at room temperature. In this way 10 previously undescribed esters of these acids were synthesised and characterised. Excellent yields were observed for most of the E isomers and the more hindered Z esters were also obtained in good yields, far better than those obtained applying the classical acid-catalysed esterification reaction.
Carbanion Chemistry from Carboxylic Acids: a Special Issue in Honor of Professor Ramón Mestres on his 65th Birthday.
Authors: Parra Margarita , Gil Salvador
Published: October 2008

This special issue of Molecules is to honour the 65th birthday of Professor Ramón Mestres.[...]
Investigations into the Use of a Polyfluorooctanol as an Auxiliary Component for an Aldol Reaction
Authors: Eames Jason , Khanom Hasina
Published: October 2008

Results are reported on the efficiency of polyfluorooctanol as a perfluorousauxiliary component in the aldol reaction between the enolate derived frompolyfluorooctyl acetate and 2-fluorobenzaldehyde. Reduction of the correspondingpolyfluoro β-hydroxy ester with Super Hydride® gave the required 1,3-diol in good yield.
Self-assembly of [2]Rotaxane Exploiting Reversible Pt(II)- Pyridine Coordinate Bonds
Authors: Ballester Pablo , Capó Magdalena , Costa Antoni , Deyà Pere M. , Frontera Antoni , Gomila Rosa M.
Published: October 2008

A dinuclear self-assembled cationic macrocycle based on Pt(II)-N(pyridine) coordinative bonds and having competitive triflate anions, as metal counterions, is used in the construction of [2]rotaxane and [2]pseudorotaxane architectures assisted by hydrogen bonding. The kinetic lability of the Pt(II)-N(pyridine) coordinative bond controls the dynamics of the [2]rotaxane.
Synthesis of Highly Functionalised Enantiopure Bicyclo[3.2.1]- octane Systems from Carvone
Authors: Abad Antonio , Agulló Consuelo , Cuñat Ana C. , De Alfonso Ignacio , Navarro Ismael , Vera Noelia
Published: October 2008

The commercially available monoterpene carvone has been efficiently convertedinto the tricyclo[3.2.1.02.7]octane and bicyclo[3.2.1]octane systems characteristic of somebiologically active compounds. The sequence used for this transformation involves as keyfeatures an intramolecular Diels-Alder reaction of a 5-vinyl-1,3-cyclohexadiene and acyclopropane ring opening.
From Labdanes to Drimanes. Degradation of the Side Chain of Dihydrozamoranic Acid.
Authors: Rodilla Jesús M.L. , Díez D. , Urones J. G. , Rocha Pedro M.
Published: October 2008

A new route for the degradation of the saturated side chain of dihydrozamoranic acid has been devised, giving an advanced intermediate, compound 14, useful for the synthesis of insect antifeedants such as warburganal and polygodial.
1-Hydroxymethyl-4-phenylsulfonybutadiene, a Versatile Building Block for the Synthesis of 2,3,4-Trisusbtituted Tetrahydrothiophenes
Authors: Díez David , Benéitez M. Templo , Marcos Isidro S. , Garrido N. M. , Basabe P. , Urones Julio G.
Published: October 2008

A method to synthesize chiral 2,3,4-trisusbtituted tetrahydrothiophenes in both enantiomerically pure forms starting from 1-hydroxymethyl-4-phenylsulfonylbutadiene is described.
Masked ω-Lithio Ester Enolates: Synthetic Applications
Authors: Yus Miguel , Torregrosa Rosario , Pastor Isidro M.
Published: October 2008

The protocol of lithiation by means of lithium and a catalytic (5% molar) amount of DTBB (4,4’-di-tert-butylbiphenyl), applied to ω-chloro ortho ester 6 under Barbier-type conditions gives, after final acid-catalyzed methanolysis, the corresponding functionalized esters 8 or 9 (for chlorotrimethylsilane as electrophile) or, after ortho ester deprotection and acid catalyzed treatment, the δ-lactones 11. The procedure is also practical for bicyclic ortho esters 14: the β-chloro OBO ester derivate generates the γ- lactones 15 and the γ-chloro OBO ester gives corresponding esters 8.
Polymer-Supported Cinchona Alkaloid-Derived Ammonium Salts as Recoverable Phase-Transfer Catalysts for the Asymmetric Synthesis of α-Amino Acids
Authors: Chinchilla Rafael , Mazón Patricia , Nájera Carmen
Published: October 2008

Alkaloids such as cinchonidine, quinine and N-methylephedrine have been N-alkylated using polymeric benzyl halides or co-polymerized and then N-alkylated, thus affording a series of polymer-supported chiral ammonium salts which have been employed as phase-transfer catalysts in the asymmetric benzylation of an N-(diphenylmethylene)glycine ester. These new polymeric catalysts can be easily recovered by simple filtration after the reaction and reused. The best ee’s were achieved when Merrifield resin-anchored cinchonidinium ammonium salts were employed.
Nucleophilic Benzoylation Using a Mandelic Acid Dioxolanone as a Synthetic Equivalent of the Benzoyl Carbanion. Oxidative Decarboxylation of α-Hydroxyacids
Authors: Blay Gonzalo , Fernández Isabel , Monje Belén , Pedro José R.
Published: October 2008

The synthesis of alkyl aryl ketones using a mandelic acid dioxolanone as a synthetic equivalent (Umpolung) of the benzoyl carbanion is reported. The methodology involves alkylation of the mandelic acid dioxolanone, hydrolysis of the dioxolanone moiety in the alkylated products and oxidative decarboxylation of the resulting α-hydroxyacids. The last step is carried out in a catalytic aerobic way using a Co (III) complex in the presence of pivalaldehyde under very mild conditions.
A Novel Strategy Towards the Asymmetric Synthesis of Orthogonally Funtionalised 2-N-Benzyl-N-α-methylbenzylamino- 5-carboxymethyl-cyclopentane-1-carboxylic acid.
Authors: Garrido Narciso M. , El Hammoumi Mohamed M. , Díez David , García Mercedes , Urones Julio G.
Published: October 2008

The asymmetric synthesis of the orthogonally funtionalised compounds tert-butyl 2-N-benzyl-N-α-methylbenzylamino-5-methoxycarbonylmethylcyclopentane- 1-carboxylate and methyl 2-N-benzyl-N-α-methylbenzylamino-5–carboxymethylcyclo- pentane-1-carboxylate by a domino reaction of tert-butyl methyl (E,E)-octa-2,6- diendioate with lithium N-α-methylbenzyl-N-benzylamide initiated by a Michael addition, subsequent 5-exo-trig intramolecular cyclisation and posterior selective hydrolysis with trifluoroacetic acid is reported.
Melbourne-RACI December Synthesis Symposium
Authors: Gill Melvyn
Published: October 2008

This special issue of Molecules celebrates the Synthesis Symposium held in The School of Chemistry at the University of Melbourne during the first week of December each and every year since 1976.[...]
Self-associated, “Distillable” Ionic Media
Authors: Kreher Ulf P. , Rosamilia Anthony E. , Raston Colin L. , Scott Janet L. , Strauss Christopher R.
Published: October 2008

Liquid or low melting association products of carbon dioxide and a secondary amine, both neutral molecules that may be gaseous, are recognised as “distillable” ionic media.
Radical Oxidative Cyclization of Spiroacetals to Bis-spiroacetals: An Overview
Authors: Brimble Margaret A.
Published: October 2008

The use of iodobenzene diacetate and iodine under photolytic conditions provides and efficient method for the oxidative cyclization of spiroacetals bearing an hydroxyalkyl side chain to bis-spiroacetals. An overview is provided of the use of this reaction for the synthesis of several bis-spiroacetal containing natural products such as the polyether antibiotics salinomycin and CP44,161 and the shellfish toxins, the spirolides.
Synthesis of Chiral Building Blocks for Use in Drug Discovery
Authors: Marino Sharon T. , Stachurska-Buczek Danuta , Huggins Daniel A. , Krywult Beata M. , Sheehan Craig S. , Nguyen Thao , Choi Neil , Parsons Jack G. , Griffiths Peter G. , James Ian W. , Bray Andrew M. , White Jonathan M. , Boyce Rustum S.
Published: October 2008

In the past decade there has been a significant growth in the sales of pharmaceutical drugs worldwide, but more importantly there has been a dramatic growth in the sales of single enantiomer drugs. The pharmaceutical industry has a rising demand for chiral intermediates and research reagents because of the continuing imperative to improve drug efficacy. This in turn impacts on researchers involved in preclinical discovery work. Besides traditional chiral pool and resolution of racemates as sources of chiral building blocks, many new synthetic methods including a great variety of catalytic reactions have been developed which facilitate the production of complex chiral drug candidates for clinical trials. The most ambitious technique is to synthesise homochiral compounds from non-chiral starting materials using chiral metal catalysts and related chemistry. Examples of the synthesis of chiral building blocks from achiral materials utilizing asymmetric hydrogenation and asymmetric epoxidation are presented.
The Preparation of Fluorescence-Quenched Probes for Use in the Characterization of Human Factor Xa Substrate Binding Domains
Authors: Bromfield Karen M. , Cianci Julia , Duggan Peter J.
Published: October 2008

The preparation and characterization by LCMS of a library of 55 fluorescence- quenched peptides is described. The peptides bear a terminal anthranilamide fluorophore and a penultimate 2,4-dinitrophenyl-L-lysine quencher, and will be used to probe the substrate binding domain of the human blood coagulation enzyme, factor Xa.
Nitrogen Heterocycles as Building Blocks for New Metallo-supramolecular Architectures
Authors: Steel Peter J.
Published: October 2008

The syntheses of representative examples of five classes of new heterocyclic ligands are described. These include N,N'-chelating bis-heterocycles, binucleating ligands, cyclometallated compounds, chiral ligands and a family of polyheteroaryl-linked arenes.
Chiral Building Blocks: Enantioselective Syntheses of Benzyloxymethyl Phenyl Propionic Acids
Authors: Parsons Jack G. , Stachurska-Buczek Danuta , Choi Neil , Griffiths Peter G. , Huggins Daniel A. , Krywult Beata M. , Marino Sharon T. , Nguyen Thao , Sheehan Craig S. , James Ian W. , Bray Andrew M. , White Jonathan M. , Boyce Rustum S.
Published: October 2008

The synthesis of (2S)-2-benzyloxymethyl-3-(2-fluoro-4-methoxyphenyl)- propionic acid, (2S)-2-benzyloxymethyl-3-(2-fluoro-4-methylphenyl)propionic acid and (2S)-2-benzyl-oxymethyl-3-(2,4-dimethylphenyl)propionic acid has been achieved by TiCl4 mediated alkylation of the corresponding (4R)-4-benzyl-3-[3-(2-fluoro-4-methoxyphenyl-, 2-fluoro-4-methylphenyl-, 2,4- dimethylphenyl-)propionyl]-2-oxazolidinones, followed by hydrolysis of the chiral auxiliary. The stereochemistry of the alkylation reaction was confirmed by an X-ray crystal structure of (4R)-4-benzyl-3-[(2S)-2-benzyloxymethyl-3-(2- fluoro-4-methylphenyl)propionyl]-2-oxazolidinone.
Development of Predictive Tools for Optimizing Organic Reactions
Authors: Roberts Brett A. , Strauss Christopher R.
Published: October 2008

Although microwave chemistry and its applications have undergone rapid growth over the last decade, the technology is not yet employed routinely in all synthetic laboratories. A significant obstacle to implementation concerns the empirical work required to adapt established conditions into alternatives employing higher temperatures. We now have established predictive tools to translate reaction conditions from conventional heated (ambient pressure) to elevated temperature (ambient or elevated pressure). We have studied 45 reactions (including published literature examples) and made in excess of 200 estimations for specific yield or conversion, with a high degree of accuracy. Linear regression analysis of estimated vs. experimental conversion or yield was 0.90 (first iteration) and 0.98 (second iteration).
Preparation of Novel Selenopenams by Intramolecular Homolytic Substitution
Authors: Carland Michael W. , Schiesser Carl H.
Published: October 2008

Photolyses of the thiohydroximate ester derivatives 13 and 21 of the 4- (benzyl-seleno)-2-azetidinoines 7 and 20, afford the 1-aza-7-oxo-4-selenabicyclo- [3.2.0]heptane ring systems 14 and 21 in good to moderate yield in processes that presumably involve intramolecular homolytic substitution at selenium with expulsion of benzyl radical. Extension of this methodology to the preparation of derivatives 24 of 12,2a-dihydro-1H,8H-azeto[2,1-b][1,3]benzoselenazin-1-one (22) is also described.
Toward Pyridine-Fused Selenium-Containing Antioxidants
Authors: Fenner Tahli , Schiesser Carl H.
Published: October 2008

Photolysis of the thiohydroximate ester derivative 21 of 2-carboethoxy-2-(2- (benzylseleno)pyridin-3-yl)tridecylcarboxylic acid (20) affords 2-dodecyl-2- carboethoxy-2,3-dihydroselenolo[2,3-b]pyridine (22) in 89% yield in a process presumably involving intramolecular homolytic substitution by a tertiary alkyl radical at selenium with loss of a benzyl radical. Work toward extending this methodology to the preparation of pyridine-fused selenium analogues of antioxidants is described.
Self-Terminating, Oxidative Radical Cyclizations
Authors: Dreessen Tim , Jargstorff Christian , Lietzau Lars , Plath Christian , Stademann Arne , Wille Uta
Published: October 2008

The recently discovered novel concept of self-terminating, oxidative radical cyclizations, through which alkynes can be converted into carbonyl compounds under very mild reaction conditions using O-centered inorganic and organic radicals as oxidants, is described
Synthesis of Pyran and Pyranone Natural Products
Authors: Donner Christopher D. , Gill Melvyn , Tewierik Leonie M.
Published: October 2008

An overview of the synthesis of the fungal metabolites (+)-dermolactone, (–)- semixanthomegnin, (+)- and (–)-mellein, (–)-ochratoxin α, (–)-(1R,3S)-thysanone, the enantiopure ventiloquinones L, E and G, and 8-desmethyleleutherin from a common chiral intermediate, is presented. Further methodology leading potentially toward extended quinones such as (3S,3'S)-xylindein is also outlined.
Synthesis and Characterisation of Macrocyclic Diamino Chiral Crown Ethers
Authors: Correa Waldo H. , Scott Janet L.
Published: October 2008

A benign and efficient synthesis of chiral macrocyclic ‘aza-crown’ ethers of varying ring size is reported. The synthesis involves a Schiff base condensation of ether linked dialdehydes of varying chain length and (1R,2R)-(–)-1,2-diaminocyclohexane under mild conditions to yield the macrocycles, which are subsequently reduced to yield the diamino analogues.
Fluorescence Studies of Selected 2-Alkylaminopyrimidines
Authors: Abdullah Z. , Tahir N. Mohd , Abas M. R. , Aiyub Z. , Low B. K.
Published: October 2008

The reactions of 2-chloropyrimidine with methylamine, ethylamine and piperidine gave the corresponding 2-N-methylamino-, 2-N-ethylamino- and 2N- piperidinopyrimidines, respectively. The fluorescence properties of these alkylamino derivatives in chloroform, ethyl acetate, carbon tetrachloride, acetone, ether, ethanol and methanol were studied. All the alkylamino derivatives showed the highest fluorescence intensity in polar protic solvents; thus 2-N-methylaminopyrimidine (highest fluorescence intensity at 377 nm when excited at 282 nm) and 2-N-ethylaminopyrimidine (highest fluorescence intensity at 375 nm, when excited at 286 nm) showed the highest fluorescence in methanol. In ethanol, 2-N-piperidinopyrimidine showed a fluorescence peak at 403 nm when excited at 360 nm and in chloroform it fluoresced at 392 nm when excited at 356 nm.
One Step Regioselective Synthesis of 5-Aminoisoxazoles from Nitrile Oxides and α-Cyanoenamines
Authors: Saad Amar , Vaultier Michel , Derdour Aïcha
Published: October 2008

The 1,3-dipolar cycloaddition of nitrile oxides to 1-cyanoenamines gives 5-aminoisoxazoles regioselectively. Moderate to good yields could be obtained depending on the method used to generate the nitrile oxides. The intermediate isoxazolines could not be isolated.
Formation of the Imidazolinone Ring Under Mild Conditions in the Presence of Sodium Hydride
Authors: Vasiliev Aleksey  N. , Lopez Antonio F. , Fernandez Julio  D. , Mocchi Anibal  J.
Published: October 2008

Substituted imidazolinones containing heterocyclic carboxylic acids as substituents and possessing herbicidal properties were synthesized by cyclization of 2-amino-2,3-dimethylbutyramide with heterocyclic ethyl dicarboxylates under mild conditions. The use of NaH as base leads to a significant increase in the reaction rate and allows the preparation of the target compounds in high yields.
Isomerization Reactions of Allylic Alcohols into Ketones with the Grubbs Reagent
Authors: Nakashima Katsuyuki , Okamoto Sanae , Sono Masakazu , Tori Motoo
Published: October 2008

Allylic alcohols were isomerized into ketones by the action of the Grubbs reagent. Some model alcohols were prepared and tested under similar conditions to reveal that less substituted alkenes rearrange more easily. More hindered alcohols are stable under these conditions, however, the simple allylic alcohols tend to isomerize producing ethyl ketone and the corresponding degraded methyl ketone.
Polymeric Complexes of Cornstarch and Waxy Cornstarch Phosphates with Milk Casein and Their Performance as Biodegradable Materials
Authors: Najgebauer Dorota , Grega Tadeusz , Sady Marek , Tomasik Piotr
Published: October 2008

Complexes of phosphated cornstarch and waxy cornstarch with casein were prepared and characterised. They were prepared from casein in defatted milk and corn and waxy corn starches phosphated to degree of substitution values (DS) of 0.0637 and 0.0968, respectively. The components were blended in starch to casein ratios of 2:1, 1:1, and 1:2, then precipitated with hydrochloric acid. Aqueous solubility, water binding capacity, IR spectra, and thermal analysis (thermogravimetry, TG, and differential thermogravimetry, DTG) of the precipitates revealed that they were not simple physical mixtures of the components. The components interact with one another electrostatically with involvement of the starch phosphate groups and the peptide bonds of casein as documented by the IR spectra. Because of their insolubility in 7 M aqueous urea solution they might also be considered as complexes in which the components were chemically bound. Enzymatic studies showed that they are biodegradable materials.
Flavone Glycosides from Calycotome Villosa Subsp. Intermedia
Authors: Antri Ali  El , Messouri Ibtissam , Tlemçani Rachida Chendid , Bouktaib Mohamed , El Alami Rachid , El Bali Brahim , Lachkar Mohammed
Published: October 2008

The known flavonoid chrysin-7-O-(β-D-glycopyranoside) (chrysin glucoside,1) as a major fraction and a new glycoside flavone, chrysin-7-O-β-D-[(6”-acetyl)glycopyranoside] (2) were isolated from the flowers and leaves of CalycotomeVillosa Subsp. Intermedia, They were identified by UV-Vis, 1R, 1H-, 13C-NMR and ESI-MS.
A Novel Synthesis of Arylpyrrolo[1,2-a]pyrazinone Derivatives
Authors: Wang Fei , Wang Jiawei , Zhang Shoufang
Published: October 2008

Some aryl-2-methyl-1-pyrrolo[1,2-a]pyrazinones were designed and prepared to study the Structure-Activity Relationships (SAR) of pyrrolo[1,2-a]pyrazinone derivatives. With methyl pyrrole-2-carboxylate as the starting material, the title compounds were prepared through N-alkylation and two novel cyclizations. Eleven aryl-2-methyl-1- pyrrolo[1,2-a]pyrazinone derivatives not previously reported in the literature are presented in this paper. Some of them show potent anti-inflammatory and analgesic activities.
Complexes of 3.6 kDa Maltodextrin with Some Metals
Authors: Tomasik Piotr , Anderegg James  W. , Schilling Christopher  H.
Published: October 2008

Preparation of magnesium, lanthanum, and bismuth(III) complexes of 3.6 kDa maltodextrin and some properties of the resulting materials are presented. The metal derivatives contain metals bound to the oxygen atoms of the hydroxyl groups of maltodextrin. Additionally, the metal atoms are coordinated to the hydroxyl groups of the D-glucose units of the macroligand. Such coordination stabilized the metal – oxygen bond against hydrolysis, even in boiling water. The presence of magnesium and lanthanum atoms increased the thermal stability of maltodextrin, whereas bismuth atoms decreased it.
Chemical Manganese Dioxide (CMD): lts Application to the Oxidative Iodination of Benzene, Halobenzenes and Some Deactivated Arenes †
Authors: Lulinski Piotr , Krassowska-Swiebocka Barbara , Skulski Lech
Published: October 2008

After comparing our previous and newer results for numerous oxidativearomatic iodination experiments using various brands of active MnO2 as the oxidants,we recommend the use of a Chemical Manganese Dioxide (Aldrich CMD; 90 %MnO2) as the oxidant of choice, since it is satisfactorily pure and chemically active, andis notably less costly than other options.
Isolation and Structure Elucidation of a Flavanone, a Flavanone Glycoside and Vomifoliol from Echiochilon Fruticosum Growing in Tunisia
Authors: Hammami S. , Jannet H.  Ben , Bergaoui A. , Ciavatta L. , Cimino G. , Mighri Z.
Published: October 2008

A flavanone and a flavanone glycoside, together with vomifoliol, have been isolated for the first time from the aerial parts of the plant Echiochilon fruticosum and identified. Their structures were established on the basis of spectroscopic measurements, mainly 2D NMR using COSY, HMQC and HMBC experiments.
Syntheses of Quinazoline-2,4-dione Alkaloids and Analogues from Mexican Zanthoxylum Species †
Authors: Rivero I.  A. , Espinoza K. , Somanathan R.
Published: October 2008

Quinazolinone and quinazolinedione derivatives are of considerable interest due to their wide array of pharmacological properties. In this paper we report the synthesis of ten quinazolinediones. The previous isolation of two of these compounds, namely 1-methyl-3-(2'-phenylethyl)-1H,3H-quinazoline-2,4-dione and 1-methyl-3-[2'-(4'- methoxyphenyl)ethyl]-lH,3H-quinazoline-2,4-dione, from the seed husks of Mexican Zanthoxylum species has been reported
Microwave-Accelerated or Conventionally Heated Iodination Reactions of Some Aromatic Amines, Using ortho-Periodic Acid as the Oxidant †
Authors: Sosnowski Maciej , Skulski Lech , Wolowik Katarzyna
Published: October 2008

A fast and simple method for the oxidative iodination of some aromatic amines, either under microwave irradiation or conventional heating, is reported, using diiodine and ortho-periodic acid as the oxidant. The reactions were carried out in boiling CH2Cl2 solutions under a reflux condenser. For the microwave assisted reactions, the reaction times were always notably shortened, but the yields were usually less influenced as compared with the conventional method.
A Facile Synthesis of Substituted Benzyl Selenocyanates†
Authors: Jacob Linda  A. , Matos Bianca , Mostafa Corey , Rodriguez Joelle , Tillotson Joanne  Kivella
Published: October 2008

Benzyl selenocyanates can be made from the corresponding benzylic bromides or chlorides in 30-60 minutes using acetonitrile as a solvent. The products may be obtained pure in satisfactory yields without recourse to chromatography.
Convenient Replacement of the Hydroxy by an Amino Group in 4 Hydroxycoumarin and 4-Hydroxy-6-methyl-2-pyrone under Microwave Irradiation
Authors: Stoyanov Edmont  V. , Ivanov Ivo C.
Published: October 2008

The reaction of 4-hydroxycoumarin (1) with some primary amines 2a-h and morpholine (2i) under microwave irradiation occurred without opening of the lactone ring to give N-substituted 4-aminocoumarins 3a-i in excellent yields. Under the same experimental conditions, 4-hydroxy-6-methyl-2-pyrone (4) reacted with benzylamine (2e) or 2-phenyl- ethylamine (2f) to give the corresponding N,N'-disubstituted 4-amino-6-methyl-2-pyridones 5e,f. The main advantages of this procedure are dramatically shortened reaction times, higher amine utilization and considerably improved yields.
A Comparative Study of O2, CO and CN Binding to Heme IX Protein Models
Authors: Torrens Francisco
Published: October 2008

Parametrization of a molecular-mechanics program to include terms specificfor five- and six-coordinate transition metal complexes results in computer-simulatedstructures of heme complexes. The principal new feature peculiar to five and sixcoordination is a term that measures the effect of electron-pair repulsion modified by theligand electronegativity and takes into account the different structural possibilities. Themodel system takes into account the structural differences of the fixing centre in thehaemoglobin subunits. The customary proximal histidine is added. The prosthetic groupheme IX is wholly considered in our model. The calculations show clearly that certainconformations are much more favourable that others for fixing O2. From the O2 bindingin haemoglobin, myoglobin and simple Fe porphyrin models it is concluded that the bentO2 ligand is best viewed as bound superoxide O2–. Axial ligands are practically free-rotating. A small modification of the model in both crystal and protein matrix affects theorientation of the ligands in experimental systems.
Isolation and X-ray Crystal Structure of Tetrahydroisoquinoline Alkaloids from Calycotome Villosa Subsp. intermedias
Authors: El Antri Ali , Messouri Ibtissam , Bouktaib Mohamed , El Alami Rachid , Bolte Michael , El Bali Brahim , Lachkar Mohammed
Published: October 2008

Two tetrahydroisoquinoline alkaloids were extracted from the alkaloid fraction of a methanol extract of the seeds of Calycotome Villosa Subsp. intermedia. Their structures were established as (R)-1-hydroxymethyl-7-8-dimethoxy-1,2,3,4-tetrahydro- isoquinoline (1) and (S)-7-hydroxymethyl-2-3-dimethoxy-7,8,9,10-tetrahydroisoquinoline chloride (2) by spectroscopic techniques and X-ray diffraction analysis.
Synthesis of Substituted Stilbenes via the Knoevenagel Condensation
Authors: Al-Shihry Shar  Saad
Published: October 2008

Knoevenagel condensations between aldehydes and substrates containing active methylene groups were carried out in ethanol at room temperature, in the presence of potassium phosphate, to afford unsymmetrical olefins. These condensations have been shown to afford only the E-isomers in greater than 80% yields. Salicylaldehyde first produces the Knoevenagel condensation products, which undergo a subsequent heterocyclization to give coumarin derivatives. The structures of the synthesized compounds were established on the basis of UV, IR, MS and NMR spectroscopy.
Leishmanicidal Activity of Passifloricin A and Derivatives
Authors: G. Wilson  Cardona , F. Winston Quiñones Quiñones , L. Fernando  Echeverri
Published: October 2008

Several natural and hemisyntetic passifloricins were assayed against Leishmania panamensis amastigotes. High leishmanicidal activity as well as toxicity was observed. The structure of a new compound is also reported.
High Throughput Screening and QSAR-3D/CoMFA: Useful Tools to Design Predictive Models of Substrate Specificity for Biocatalysts†
Authors: Carballeira J. D. , Quezada M.  A. , Álvarez E. , Sinisterra J.  V.
Published: October 2008

After a hierarchical microbial screening process, new microorganisms have been discovered that act as biocatalysts for the stereoselective oxidation of secondary alcohols or for ketone reduction. Oxidation activity is more widespread in yeasts and bacteria, while actinomycetes, filamentous fungi and yeasts present the highest reduction activities. QSAR-3D/CoMFA is an adequate technique to design predictive models of the biocatalysts’ activity. In this paper CoMFA models are designed to compare the activities of the biocatalysts selected for the oxidation of alcohols and for the reduction of ketones, starting from the results obtained during the screening process. These models are useful for learning about the activity of these microorganisms and to compare the substrate specificity requirements between alcohol oxidation and ketone reduction biocatalysts.
Synthesis of Some Novel 11b-Substituted Pyrimido[6,1-a]-isoquinoline Derivatives
Authors: Angelov Plamen  A. , Ivanov Iliyan  I. , Venkov Atanas   P.
Published: October 2008

A series of novel 11b-substituted 1,6,7,11b-tetrahydropyrimido[6,1-a]- isoquinoline-2,4-diones and 4-thioxo-1,3,4,6,7,11b-hexahydropyrimido[6,1-a]isoquinolin-2- ones were synthesized, utilizing two alternative strategies for ring closure of tetrahydroisoquinoline intermediates obtained from N-phenethyl enaminones
Synthesis of Benzoxazinone Derivatives: A New Route to 2 (N Phthaloylmethyl)-4H-3,1-benzoxazin-4-one
Authors: Shariat Mehdi , Abdollahi Sohrab
Published: October 2008

A new method has been designed to prepare the known benzoxazinone derivative 2-(N-phthaloylmethyl)-4H-3,1-benzoxazin-4-one (4). The acyl chloride derivative N-phthaloylglycine reacts with anthranilic acid in chloroform, in the presence of triethylamine, to give an intermediate that is then reacted with cyanuric chloride, used as a cyclization agent, to produce the benzoxazinone derivative.
“Seek, and ye shall find” (Matthew 7:7)
Authors: Rawson Jeremy , Catalán Antonio
Published: October 2008

The preparation and characterisation of organic molecular magnets is a non-trivial task which touches on many contemporary issues within chemistry.[...]
New π-Delocalized Persistent Radicals
Authors: Kaszynski Piotr
Published: October 2008

Progress in the theoretical and experimental investigation of heterocyclic radicals suitable for incorporation into the structure of a liquid crystalline molecule is described. Five classes of heterocyclic systems are discussed, including their methods of preparation, stability and further functionalization to form potentially mesogenic materials.
The Effects of Conjugation Path Variation on Electron Delocalization in Phenoxyl-Based Systems.
Authors: Liu Yanbing , Lahti Paul M.
Published: October 2008

A number of persistent 2,6-di-tert-butylphenoxyl based radicals were synthesized as models for unpaired spin delocalization as a function of conjugation pathway, and were investigated by ESR and UV-vis spectroscopy. Phenoxyl spin delocalizes significantly onto a para-phenyl ring, but further delocalization through a meta-vinyl or meta-carbonyl linkage is not detectable by ESR hyperfine coupling. UV- vis spectra do show a red shift of the longest wavelength transition for a carbonyl-type substituent by comparison to a vinyl substituent in the meta-position of a para-phenyl group. By comparison, a para-styryl substituent on the phenoxyl causes very large spin delocalization from the phenoxyl unit, with the largest hyperfine coupling being found on the ethenyl unit of the assemblage. This large delocalization accounts for the reactivity of radicals that incorporate such units.
N-Salicylideneamine Derivatives with TEMPO Substituents
Authors: Hata Masayuki , Akutsu Hiroki , Yamada Jun-ichi , Nakatsuji Shin’ichi
Published: October 2008

Three N-salicylideneamine derivatives bearing TEMPO (2,2,6,6-tetra- methyl-1-piperidinyloxy) substituents were prepared in order to study their structure and property relationships and to investigate the possibilities of the existence of heat and/or light responsive magnetic properties. Curie-Weiss behavior with weak ferromagnetic intermolecular spin-spin interactions was observed in one of the radicals, while antiferromagnetic interactions were predominant for the other radicals and the structure-property relationships were investigated for the radical compounds from their crystal structures obtained by X-ray analyses. Preliminary results of the examination of their responses towards light and heat are also described.
A First-Principles Analysis of the Magnetism of CuII Polynuclear Coordination Complexes: the Case of [Cu4(bpy)4(aspartate)2(H2O)3](ClO4)4•2.5H2O
Authors: Deumal Mercè , Ribas-Ariño Jordi , Robb Michael A. , Ribas Joan , Novoa Juan J.
Published: October 2008

The magnetic structure of the [Cu4(bpy)4(aspartate)2(H2O)3](ClO4)4·2.5 H2Ocrystal — using fractional coordinates determined at room-temperature — has beenanalysed in detail. This analysis has been carried out by extending our first principlesbottom-up theoretical approach, which was initially designed to study through-spacemagnetic interactions, to handle through-bond magnetic interactions. The only input datarequired by this approach are the values of the computed JAB exchange parameters for allthe unique pairs of spin-containing centres. The results allow the magnetic structure ofthe crystal, which presents two types of isolated tetranuclear CuII clusters, to be definedin quantitative terms. Each of these clusters presents ferro and antiferromagneticinteractions, the former being stronger, although outnumbered by the latter. Thecomputed magnetic susceptibility curve shows the same qualitative features as theexperimental data. However, there are small differences that are presumed to beassociated with the use of room-temperature crystal coordinates.
Synthesis and Magnetic Properties of the Novel Dithiadiazolyl Radical, p-NCC6F4C6F4CNSSN
Authors: Alberola Antonio , Less Robert J. , Palacio Fernando , Pask Christopher M. , Rawson Jeremy M.
Published: October 2008

The dithiadiazolyl radical p-NCC6F4C6F4CNSSN• (4) retains its monomericnature in the solid state with molecules linked together into chains via supramolecularCN···S interactions. Variable temperature magnetic studies on 4 show that it behaves as anear-ideal Curie paramagnet (|θ| less than 0.1 K), indicating negligible intermolecularexchange. The effective magnetic moment (1.78 μB) is temperature independent and inexcellent agreement with the value expected for an S = 1⁄2 paramagnet with g = 2.01(1.74μB). The lack of exchange coupling between radicals is attributed to the absence ofsignificant orbital overlap between radical centres.
Restricting Magnetic Interaction Pathways in Polyoxometalate Salts of Cationic Nitronyl Nitroxide Free Radicals
Authors: Tarazón Ana , Giménez-Saiz Carlos , Gómez-García Carlos J. , Romero Francisco M.
Published: October 2008

Salts 1 and 2 that combine the [W6O19]2- Lindqvist anion with the cationicnitronyl nitroxide (NN) free radicals p-MepyNN+ and nBu3NCH2NN+ , respectively, havebeen synthesized and their structural and magnetic properties have been studied.
Theoretical Studies on Electronic States of Rh-C60. Possibility of a Room-temperature Organic Ferromagnet
Authors: Nakano S. , Kitagawa Y. , Kawakami T. , Okumura M. , Nagao H. , Yamaguchi K.
Published: October 2008

A possible mechanism for a ferromagnetic interaction in the rhombic (Rh) formof C60 (Rh-C60) is suggested on the basis of theoretical studies in relation to cage distortionof the C60 unit in the polymerized 2D-plane. Band structure calculations on Rh-C60 showthat cage distortion leads to competition between diamagnetic and ferromagnetic states,which give rise to the possibility of thermally populating the ferromagnetic state.
Studies on TMPD:TCNB; a Donor-Acceptor with Room Temperature Paramagnetism and n-π Interaction†
Authors: Ghalsasi Prasanna S. , Cage Brant , Yarger J. L.
Published: October 2008

A donor-acceptor compound based on N,N,N′,N′-tetramethyl-p-phenylene-diamine and 1,2,4,5-tetracyanobenzene (TMPD:TCNB) has been synthesized. The crystalstructure of the black 1:1 complex formed between TMPD and TCNB has beendetermined by single crystal X-ray diffraction at room temperature. The compoundcrystallizes in the triclinic space group P-1 with cell dimensions: a = 7.4986(15) å, b =7.6772(11) å, c = 8.0764(15) å, α = 78.822(12)°, β = 83.3779(19)°, γ = 86.289(17)°.TMPD and TCNB molecules are stacked alternately in infinite columns along the a-axis.The structure does not seem to show the usual π-π interaction between the two aromaticrings, but indicates an n-π interaction localized between the nitrogen atoms of the donorand the cyano groups of the acceptor.
Synthesis of Novel Azo Schiff Bases and Their Antibacterial and Antifungal Activities
Authors: Jarrahpour A.  A. , Motamedifar M. , Pakshir K. , Hadi N. , Zarei M.
Published: October 2008

Ten new azo Schiff bases 5a-h and 7a-b were prepared in excellent yields via the condensation of different aromatic amines and a new azoaldehyde, 2-hydroxy-3- methoxy-5-(4-methoxyphenylazo)benzaldehyde (4) by two different methods. All new compounds were tested against five microorganisms: Staphylococcus aureus (Gram positive and methicillin resistant), Bacillus subtilis (Gram positive), Kelebsiella pneumonia, Pseudomonas aeruginosa and Escherichia coli (all Gram negative). Compounds 4, 5a, 5c, 5d and 5g were moderately active against Staphylococcus aureus and Bacillus subtilis. Compound 7b was highly active against Bacillus subtilis and moderately active against Staphylococcus aureus. Other compounds were inactive against these strains of bacteria. The antifungal activities of these compounds were also tested against eight different fungal species. None of them were active against the fungi species tested.
Synthesis and Reactions of N-Methylbenzylammonium Fluorochromate(VI) on Silica Gel, a Selective and Efficient Heterogeneous Oxidant
Authors: Kassaee M.  Z. , Sayyed-Alangi S. Z. , Sajjadi-Ghotbabadi H.
Published: October 2008

N-Methylbenzylammonium fluorochromate(VI) (MBAFC) is easily synthesized by addition of N-methylbenzylamine to an aqueous solution of CrO3 and HF. MBAFC shows selectivity in the oxidation of aryl alcohols to their corresponding aldehydes and ketones under mild conditions. The durability, ease of work up and efficiency of MBAFC are considerably increased upon its absorption on silica gel.
Electron-Induced (EI) Mass Fragmentation is Directed by Intra- molecular H-Bonding in Two Isomeric Benzodipyran Systems
Authors: Van der Schyf Cornelis  J. , Mabic Stéphane
Published: October 2008

The striking differences observed in the electron-induced (EI) mass fragmentationpathways of two isomeric benzodipyrans are attributable to hydrogen bonding in thesemolecules. In the "angular" isomer, 6-butyryl-5-hydroxy-2,2,8,8-tetramethyl-3,4,9,10-tetra-hydro-2H,8H-benzo[1,2-b:3,4-b1]dipyran (2), H-bonding occurs between the aromatic OHgroup and the alpha carbonyl moiety contained in the ortho-phenone group, whereas in the"linear" isomer, 10-butyryl-5-hydroxy-2,2,8,8-tetramethyl-3,4,6,7-tetrahydro-2H,8H-benzo-[1,2-b:5,4-b1]dipyran (3), the aromatic OH group is para to the phenone moiety, effectivelyprecluding any H-bonding. Semi-empirical molecular orbital calculations (AM1) were used tocompare predicted sites of ionization with associated fragmentation patterns. In bothmolecules, the highest occupied molecular orbital (HOMO) was located predominantly on thearomatic moiety. Similarly, in the radical cation species of both compounds, maximum spindensity was located over the aromatic rings. Neither the HOMO nor the spin density mapsprovided a rational explanation for the differences in fragmentation patterns of the twobenzodipyran isomers. The H-bonding favors EI alpha aromatic ring C-O bond cleavage in the"angular" benzodipyran and in 5,7-dihydroxy-2,2-dimethyl-8-butyryl chroman (1), a relatedmonochroman also containing a hydrogen proximal to the aromatic ring C-O bond. In contrast,fragmentation of the "linear" benzodipyran followed a different route, which was exhibited byits base peak resulting from the loss of a propyl group from the butyryl side-chain.
A Novel Approach to the Synthesis of 6-Amino-7-hydroxy-flavone
Authors: Tang Lijun , Zhang Shufen , Yang Jinzong , Gao Wentao , Cui Jian , Zhuang Tianyu
Published: October 2008

A novel approach to the synthesis of 6-amino-7-hydroxyflavone (1) is described. Reaction in acetone of 2′,4′-dihydroxy-5′-nitroacetophenone and benzoyl chloride in the presence of potassium carbonate affords 3-benzoyl-7-hydroxy-6-nitroflavone, which is cleaved in 5% ethanolic potassium hydroxide to give 1-(2,4-dihydroxy-5-nitrophenyl)-3- phenyl-1,3-propanedione. The 1,3-diketone thus formed is then transformed into 7-hydroxy- 6-nitroflavone, followed by reduction to afford the title compound.
Unexpected Hydrazinolysis Behaviour of 1-Chloro-4-methyl-5H-pyridazino[4,5-b]indole and a Convenient Synthesis of New [1,2,4]-Triazolo[4’,3’:1,6]pyridazino[4,5-b]indoles
Authors: El-Kashef Hussein , Farghaly Abdelrahman  A. H. , Haider Norbert , Wobus Andrea
Published: October 2008

Reaction of the title compound with hydrazine in the presence of air gives the 1-unsubstituted parent system via oxidative dehydrazination of the 1-hydrazino intermediate. The latter can be obtained in high yield by carrying out the hydrazinolysis step under inert gas, and it is smoothly converted into [1,2,4]-triazolo[4’,3’:1,6]pyridazino[4,5- b]indoles.
Synthesis and Spectroscopic Characterization of New Schiff Bases Containing the Benzo-15-Crown-5 Moiety
Authors: Hayvalı Zeliha , Hayvalı Mustafa , Dal Hakan
Published: October 2008

New crown ether Schiff base derivatives were prepared by the condensation of4’-formylbenzo-15-crown-5 or 4’-formyl-5’-hydroxybenzo-15-crown-5 with 1,2-bis(2-aminophenoxy)ethane. The structures of these new compounds were confirmed on thebasis of elemental analysis, IR, 1H- and 13C-NMR, UV-Vis and mass spectroscopic data.
Reactivity of 2-Thiohydantoins Towards Various Electrophilic Reagents: Applications to the Synthesis of New 2-Ylidene-3,5-dihydro-4H-imidazol-4-ones.
Authors: Chérouvrier Jean-René , Carreaux François , Bazureau Jean  Pierre
Published: October 2008

A new route to 5-(imidazolidin-2-ylidene)-2-methylsulfanyl-3,5-dihydro-imidazol-4-ones 4a-c using ketene dithioacetal intermediates 3a-c is described. Thereactivity of thiohydantoin derivatives 2a-c towards N,N-dimethylformamide diethylacetal(DMF-DEA) was also explored using solvent-free technique under microwave irradiation(μω). The 1H- and 13C-NMR spectra of some representative products are discussed.
Crystal Structure and Characterization of the Dinuclear Cd(II) Complex [Cd(H2O)2(ο-HOC6H4COO)2]2
Authors: Jian Fangfang , Xiao Hailian , Sun Pingping , Zhao Pusu
Published: October 2008

The structure of a new binuclear cadmium (II) complex, [Cd(H2O)2(Sal)2]2 (Sal= salicylate), has been determined by X-ray crystallography. It was also characterized byelemental analysis, its IR spectrum and thermogravimetric-differential scanningcalorimetry (TG-DSC). It crystallizes in the monoclinic system, space group P21/c, withlattice parameters a = 15.742(3) å, b = 12.451(3) å, c = 7.7225(15) å, β = 96.07(3)o andZ = 4. Two cadmium (II) ions are bridged by two μ2-carboxy oxygen atoms. Eachcadmium atom lies in a distorted capped octahedron coordination geometry. The thermalgravimetry (TG) data indicate that there are four discrete decomposition steps with twoendothermic peaks and one exothermic peak. The final thermal decomposition product isCdO.
Theoretical Study of Some Nitrososulfamide Compounds with Antitumor Activity
Authors: Djameleddine Khatmi , Soumeya Seridi , Fatiha Madi
Published: October 2008

The lowest-energy conformations of four 2-chloroethylnitrososulfamides were determined using the MM+ molecular mechanics method as implemented in Hyperchem 6.0. Some of the calculated structural parameters, angles and bonds lengths were compared with the crystal structure data of N-nitroso-N-(2-chloroethyl)-N’-sulfamoyl- proline. Using MM+, AM1 and PM3 the anti conformation was predicted to be more stable than the syn conformation in each of these compounds. With these methods we found that the relative energy of the transition state (TS) was considerably higher, but with the ab initio method using RHF with minimal basic function STO-3G we found that the syn conformation is predicted to be slightly more stable. The determination of some atomic charges of a selection of atoms on the syn, anti and TS structures of the various compounds provided some details about the nature of the transition state.