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Molecules, Volume 5, Issue 3 (March 2000), Pages 200-636

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Editorial

Jump to: Research, Other

Open AccessEditorial Proceedings of the 12th National Symposium of Organic Chemistry (XII SINAQO), Los Cocos, Cordoba, Argentina, 14-17 November 1999
Molecules 2000, 5(3), 252-282; doi:10.3390/50300252
Published: 22 March 2000
PDF Full-text (122 KB)
Abstract This Paper is downloadable at http://www.mdpi.org/molecules/papers/50300252.pdf Full article
Open AccessEditorial Foreword to the Proceedings of the 12th National Symposium of Organic Chemistry "Dr. Eduardo Guerreiro", Los Cocos (Córdoba), Argentina, 14-17 November 1999
Molecules 2000, 5(3), 283-284; doi:10.3390/50300283
Published: 22 March 2000
PDF Full-text (12 KB)

Research

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Open AccessArticle Chemistry of Pyrones, Part 3: New Podands of 4H-Pyran-4-ones
Molecules 2000, 5(3), 200-207; doi:10.3390/50300200
Received: 2 February 2000 / Accepted: 14 February 2000 / Published: 1 March 2000
Cited by 3 | PDF Full-text (36 KB)
Abstract New derivatives of 3,5-disubstituted 4H-Pyran-4-one podands (9-15) were prepared by transesterification reaction of dimethyl or diethyl 2,6-dimethyl-4H-pyran-4-one-3,5-dicarboxylate with some glycol, glycol ethers or by nucleophilic substitution of some phenols or glycol ethers with 3,5-bis (bromomethyl)-2,6-diphenyl-4H-pyran-4-one. Full article
Open AccessArticle Synthesis of Some 2, 6-Disubstituted 4-Amidopyridines and -Thioamidopyridines, and Their Antimycobacterial and Photosynthesis-Inhibiting Activity
Molecules 2000, 5(3), 208-218; doi:10.3390/50300208
Received: 8 March 1999 / Accepted: 28 February 2000 / Published: 3 March 2000
Cited by 6 | PDF Full-text (41 KB)
Abstract A group of 26 new 2-halogeno-6-alkylsulfanyl- and 2,6-bis-alkylsulfanyl-4-amidopyridines and corresponding thioamidopyridines was synthesised. Some of the amidopyridines and all thioamidopyridines were tested for their antimycobacterial activity against atypical mycobacterial strains. Promising photosynthesis-inhibiting activity was also found for some of the amidopyridines. Full article
Open AccessArticle Crystal Structure of Methyl 4-Acetamido-4-cyano-4,6-dideoxy-2,3-O-isopropylidene-ß-D-allopyranoside
Molecules 2000, 5(3), 219-226; doi:10.3390/50300219
Received: 17 February 2000 / Accepted: 28 February 2000 / Published: 2 March 2000
Cited by 1 | PDF Full-text (60 KB)
Abstract
The detailed structure of methyl 4-acetamido-4-cyano-4,6-dideoxy-2,3-Oisopropylidene-ß-D-allopyranoside was established by X-ray analysis confirming allo configuration at C-4 and suggesting a 4C1 conformation of the pyranose ring. The values of relevant torsion angles and calculated puckering parameters revealed a distortion into the [...] Read more.
The detailed structure of methyl 4-acetamido-4-cyano-4,6-dideoxy-2,3-Oisopropylidene-ß-D-allopyranoside was established by X-ray analysis confirming allo configuration at C-4 and suggesting a 4C1 conformation of the pyranose ring. The values of relevant torsion angles and calculated puckering parameters revealed a distortion into the direction of 0H5, thus indicating a flattening at C-1 and C-4. Full article
Open AccessArticle Design and Synthesis of a Conformationally Rigid Mimic of the Dihydropyrimidine Calcium Channel Modulator SQ 32,926
Molecules 2000, 5(3), 227-239; doi:10.3390/50300227
Received: 9 February 2000 / Accepted: 29 February 2000 / Published: 3 March 2000
Cited by 52 | PDF Full-text (122 KB)
Abstract A conformationally rigid polyheterocycle (3) which mimics the putative receptorbound conformation of dihydropyridine-type calcium channel modulators is prepared in a seven-step reaction sequence based on a Biginelli-type cyclocondensation reaction. Full article
Open AccessArticle DDQ/PbO2: a Novel Oxidation System for Hindered Electron Rich Benzhydrols
Molecules 2000, 5(3), 240-244; doi:10.3390/50300240
Received: 11 November 1999 / Revised: 23 February 2000 / Accepted: 6 March 2000 / Published: 14 March 2000
Cited by 5 | PDF Full-text (26 KB)
Abstract A convenient mild protocol for oxidation of highly hindered electron rich benzhydrols using DDQ / PbO2 has been developed. Full article
Open AccessArticle Heterocyclic Tricycles as Internal N-Glycosides from 2-Methyl-5-nitro-6-(2-nitrophenyl)-4-phenyl(2-furyl)tetrahydropyranols
Molecules 2000, 5(3), 245-251; doi:10.3390/50300245
Received: 10 February 2000 / Accepted: 14 March 2000 / Published: 16 March 2000
PDF Full-text (69 KB)
Abstract 1-Methyl-10-nitro-11-phenyl(2-furyl)-2-aza-13-oxa-tricyclo[7.3.1.03,8]trideca-3,5,7-trienes 3 were synthesized via the reduction of the aromatic 2-nitro group of 2-methyl-5-nitro-6-(2-nitrophenyl)-4-phenyl(2-furyl)tetrahydropyranols 2 and subsequent condensation with their anomeric OH group. As by-products, the corresponding 6-(2-aminophenyl)-2-methyl-5-nitro-4-phenyl(2-furyl)tetrahydropyranols 4 were isolated. Full article
Open AccessArticle Synthesis of Crown Ethers Containing a Rubicene Moiety
Molecules 2000, 5(3), 620-628; doi:10.3390/50300620
Received: 10 February 2000 / Accepted: 14 March 2000 / Published: 22 March 2000
Cited by 3 | PDF Full-text (39 KB)
Abstract A symmetrically disubstituted derivative of the highly fluorescing and photostable rubicene was incorporated in a macrocycle using high dilution conditions and a hydroxyrubicene was functionalized with a modified aminobenzo-15-crown-5. Full article
Open AccessArticle New Conjugated Systems Derived from Piperazine-2,5-dione
Molecules 2000, 5(3), 629-636; doi:10.3390/50300629
Received: 8 March 1999 / Revised: 25 November 1999 / Accepted: 30 December 1999 / Published: 10 March 2000
Cited by 2 | PDF Full-text (31 KB)
Abstract
The preparation of monoarylidene and both symmetrical and unsymmetrical bisarylidene derivatives of piperazine-2,5-dione is described. The use of 1,4-diacetylpiperazine-2,5-dione make it possible to prepare unsymmetrical bisarylidenes. The introduction of a dicyanomethylene moiety into the para position of one of the arylidene groups [...] Read more.
The preparation of monoarylidene and both symmetrical and unsymmetrical bisarylidene derivatives of piperazine-2,5-dione is described. The use of 1,4-diacetylpiperazine-2,5-dione make it possible to prepare unsymmetrical bisarylidenes. The introduction of a dicyanomethylene moiety into the para position of one of the arylidene groups gave a remarkable deepening in the colour of the resulting compounds 11 and 16. Full article

Other

Jump to: Editorial, Research

Open AccessAbstract Plant Secondary Metabolites as Potential Anticancer Agents and Cancer Chemopreventives
Molecules 2000, 5(3), 285-288; doi:10.3390/50300285
Published: 22 March 2000
Cited by 2 | PDF Full-text (26 KB)
Open AccessAbstract Experimental and Theoretical studies on the Mechanism of Grignard Reagent Formation
Molecules 2000, 5(3), 289; doi:10.3390/50300289
Published: 22 March 2000
Cited by 1 | PDF Full-text (9 KB)
Open AccessAbstract Enzymes in Organic Solvents: the Use of Lipases and (R)-Oxynitrilase for the Preparation of Products of Biological Interest
Molecules 2000, 5(3), 290-292; doi:10.3390/50300290
Published: 22 March 2000
Cited by 2 | PDF Full-text (23 KB)
Abstract
The use of enzymes in organic solvents has acquired a special relevance in organic synthesis, and lipases are the enzymes most commonly used in transesterication reactions. In the past few years, we have shown the utility of enzymatic aminolysis and ammonolysis reactions [...] Read more.
The use of enzymes in organic solvents has acquired a special relevance in organic synthesis, and lipases are the enzymes most commonly used in transesterication reactions. In the past few years, we have shown the utility of enzymatic aminolysis and ammonolysis reactions for the preparation of amides and for the resolution of esters and amines. The enzymatic alkoxycarbonylation reaction is of great utility in chemoselective reactions of natural products. Lipases, enzymes much less exploited in organic synthesis, have an increasing interest, especially the use of (R)-oxynitrilases for the synthesis of optically active cyanohydrins. Full article
Open AccessAbstract Aziridine Carboxylates, Carboxamides and Lactones: New Methods for Their Preparation and Their Transformation into α- and β-Amino Acid Derivatives
Molecules 2000, 5(3), 293-298; doi:10.3390/50300293
Published: 22 March 2000
Cited by 8 | PDF Full-text (56 KB)
Abstract
The preparation of a variety of novel aziridine-γ-lactones (3) from carbohydrates is described. In contrast to aziridine-2-carboxylates, the lactones react regiospecifically at C-2 with soft nucleophiles to provide optically pure substituted β-amino acid precursors. Hard nucleophiles react exclusively at the C-3 position [...] Read more.
The preparation of a variety of novel aziridine-γ-lactones (3) from carbohydrates is described. In contrast to aziridine-2-carboxylates, the lactones react regiospecifically at C-2 with soft nucleophiles to provide optically pure substituted β-amino acid precursors. Hard nucleophiles react exclusively at the C-3 position to provide α-amino acid precursors. The utility of this methodology was demonstrated by the preparation of (3S,4S)-dihydroxy-L-glutamic acid (DHGA) from the appropriate aziridine-γ-lactone. DHGA was subsequently shown to be a selective partial agonist of mGluR1 receptors. A more concise preparation of aziridine-γ-lactones was achieved by 1,4-Michael addition of benzylamine to 2-O-triflylbutenolides. Use of a 2-O-mesylbutenolide led, under the same conditions, to the corresponding aziridine-2-carboxamides or 2-carboxylates. Finally, a new Evanstype aziridinating agent, Ses-iminoiodinane, was developed and shown to react efficiently with unsaturated substrates to give the corresponding aziridines, whose N-Ses protecting groups can be removed under mild conditions. Full article
Open AccessAbstract Targeting DNA with Anthracyclines: The Importance of the Sugar Moiety
Molecules 2000, 5(3), 299-301; doi:10.3390/50300299
Published: 22 March 2000
Cited by 9 | PDF Full-text (21 KB)
Open AccessAbstract Chemistry of the Calceolaria Genus. Structural and Biological Aspects
Molecules 2000, 5(3), 302-303; doi:10.3390/50300302
Published: 22 March 2000
Cited by 9 | PDF Full-text (15 KB)
Abstract
Autochthonous species of the Calceolaria (Scrophulariaceae) genus are studied. From their apolar extracts 55 new diterpenes of six skeleton types, naphtoquinones and flavonoids have been isolated. Among the different diterpenes malonic substitutions and bis-diterpenes in which both units are joined by a [...] Read more.
Autochthonous species of the Calceolaria (Scrophulariaceae) genus are studied. From their apolar extracts 55 new diterpenes of six skeleton types, naphtoquinones and flavonoids have been isolated. Among the different diterpenes malonic substitutions and bis-diterpenes in which both units are joined by a malonic acid unit stand out. Pimaranes present C-9 epimerisation and, consequently, H-9 has the same orientation as Me-20. From C.sessilis naphthoquinones with antichagasic activity have been isolated; and the biotransformation of 2α,19-dihydroxy-9-epi-entpimara-7,15-diene with Giberella fujikuroi produced 7 new diterpenes. Full article
Open AccessAbstract Synthesis of Polymers with Electro-optical Properties
Molecules 2000, 5(3), 304-306; doi:10.3390/50300304
Published: 22 March 2000
Cited by 1 | PDF Full-text (21 KB)
Open AccessAbstract Mechanisms of Water Catalysed Reactions
Molecules 2000, 5(3), 307-308; doi:10.3390/50300307
Published: 22 March 2000
Cited by 1 | PDF Full-text (16 KB)
Open AccessAbstract N-Alkyl-N-methylacetamidinium Ions. Isomerization and Water Catalyzed Exchange Rates in D2O
Molecules 2000, 5(3), 309-310; doi:10.3390/50300309
Published: 22 March 2000
PDF Full-text (15 KB)
Open AccessAbstract Natural Inhibitors of the Aromatase Enzyme
Molecules 2000, 5(3), 311-312; doi:10.3390/50300311
Published: 22 March 2000
PDF Full-text (15 KB)
Abstract The results of three years of search for natural aromatase inhibitors will be presented. Full article
Open AccessAbstract Synthesis of New Anthihelmintic Analogs of Marine Natural Products
Molecules 2000, 5(3), 313-314; doi:10.3390/50300313
Published: 22 March 2000
PDF Full-text (15 KB)
Abstract The synthesis of new anthelmintic compounds derived from 2-amine-4-hydroxy-δ-valerolactams and 2,4-dialkylthiazoles is described. The synthetic procedures and biological activity data for these compounds will be presented. Full article
Open AccessAbstract Synthesis of Derivatives of Biogenic Amines Labelled with Radioactive Tracers for Brain Imaging
Molecules 2000, 5(3), 315-316; doi:10.3390/50300315
Published: 22 March 2000
PDF Full-text (15 KB)
Abstract Endogenous derivatives of biogenic amines, such as phenethylamines, indolalkylamines and harmines, have been extensively studied as usual constituents of body fluids. Methylated derivatives of indolalkylamines have been also related to mental disorders, e.g. schizophrenia and hallucination. Full article
Open AccessAbstract Role of Weak Molecular Interactions in the Mechanism of Action of a Series of Antihelmintics
Molecules 2000, 5(3), 317-318; doi:10.3390/50300317
Published: 22 March 2000
Cited by 3 | PDF Full-text (15 KB)
Abstract Different physicochemical properties such as solute-solute and solute-solvent interactions, tautomerism, lipophilicity and solubility in water were determined for a serie of 6,7-diaryl-pteridines in order to relate those properties with their nematocide action. Full article
Open AccessAbstract The AlCl3–L Reagent and its Application to the Regioselective Carbon–Carbon Bond Formation
Molecules 2000, 5(3), 319-320; doi:10.3390/50300319
Published: 22 March 2000
PDF Full-text (17 KB)
Abstract Use of the AlCl3–L reagent in the regioselective acylation of benzodioxinic derivatives. Spectroscopic studies show the presence of coordination compounds as reaction intermediates, being the responsible of the observed regioselectivity. Full article
Open AccessAbstract A Short Synthesis of the Main Lactone Ketal Backbone Present in Saudin
Molecules 2000, 5(3), 321-322; doi:10.3390/50300321
Published: 22 March 2000
Cited by 3 | PDF Full-text (17 KB)
Abstract We are describing a brief stereospecific synthesis of a model compound related to Saudin, with a lactone ketal backbone present in the natural product starting from a tricyclic epoxiketal. Full article
Open AccessAbstract Using Empirical Rules from 13C NMR Analysis to Determine the Stereochemistry of the Epoxide Located at the 5,6-position of Decalinic Systems
Molecules 2000, 5(3), 323-324; doi:10.3390/50300323
Published: 22 March 2000
Cited by 1 | PDF Full-text (15 KB)
Abstract
An empiric rule derived from the analysis of the 13C NMR spectral data, allowed us to determine 5,6-epoxide stereochemistry on decalinic systems and a discussion of the scope and limitations of this rule and its extension to other carbon squeletons, is [...] Read more.
An empiric rule derived from the analysis of the 13C NMR spectral data, allowed us to determine 5,6-epoxide stereochemistry on decalinic systems and a discussion of the scope and limitations of this rule and its extension to other carbon squeletons, is presented. Full article
Open AccessAbstract Biotransformation of Ilicic Alcohol with Aspergillus Niger
Molecules 2000, 5(3), 325-326; doi:10.3390/50300325
Published: 22 March 2000
Cited by 2 | PDF Full-text (16 KB)
Abstract 3β-hidroxyilicic alcohol was obtained from of ilicic alcohol using cultures of Aspergillus niger. Full article
Open AccessAbstract Applications of Olefination Reactions to Cassiol Synthesis
Molecules 2000, 5(3), 327-329; doi:10.3390/50300327
Published: 22 March 2000
PDF Full-text (20 KB)
Abstract Olefination reactions directed to the synthesis of cassiol from compounds 2-5 will be discussed. Full article
Open AccessAbstract New Anti-Neoplastics Obtained by a Molecular Connectivity Method
Molecules 2000, 5(3), 330-331; doi:10.3390/50300330
Published: 22 March 2000
PDF Full-text (16 KB)
Abstract
Molecular Connectivity is a method, which allows to discriminate different pharmacological activities on the basics of numeric parameters of the molecules in study, related with specific and exclusive indexes. In the present study, we propose two potentially anti-neoplasic compounds: tricromil and zomepirac [...] Read more.
Molecular Connectivity is a method, which allows to discriminate different pharmacological activities on the basics of numeric parameters of the molecules in study, related with specific and exclusive indexes. In the present study, we propose two potentially anti-neoplasic compounds: tricromil and zomepirac, by analyzing more than a hundred different chemicals. Full article
Open AccessAbstract Octyl Phenol Synthesis Using Natural Clays
Molecules 2000, 5(3), 332-333; doi:10.3390/50300332
Published: 22 March 2000
PDF Full-text (15 KB)
Abstract
A series of clay minerals, HB, NB and Al-PILC have been studied in the alkylation reactions of 2-octanol with phenol at 180°C, under conditions of alcohol/phenol = 1 (mole ratio) and W/FAo °= 64,27 ghmol-1. The selectivity of Al-PILC was [...] Read more.
A series of clay minerals, HB, NB and Al-PILC have been studied in the alkylation reactions of 2-octanol with phenol at 180°C, under conditions of alcohol/phenol = 1 (mole ratio) and W/FAo °= 64,27 ghmol-1. The selectivity of Al-PILC was 77,12% for octyl phenol and 16,5% for dioctyl phenol. Full article
Open AccessAbstract Total Synthesis of Marchantinquinone
Molecules 2000, 5(3), 334-335; doi:10.3390/50300334
Published: 22 March 2000
Cited by 1 | PDF Full-text (21 KB)
Abstract During the last years, many bisbibenzylic macrocyclic ethers were isolated and identified in Hepaticae. One of them is MARCHANTINQUINONE, a quinonic macrocycle with interesting biological activity. In the following report, we present the last steps of the total synthesis. Full article
Open AccessAbstract Catalytic Epoxidation of Limonene
Molecules 2000, 5(3), 336-337; doi:10.3390/50300336
Published: 22 March 2000
Cited by 5 | PDF Full-text (16 KB)
Abstract The epoxidation of limonene with hidrogen peroxide was studied over zeolite Tibeta (a large pore material) and heteropoly acids on carbono and alumina supported. PW11/C was catalyst the best tested. Full article
Open AccessAbstract Base-Catalyzed Formation of Imidazole Derivatives
Molecules 2000, 5(3), 338-339; doi:10.3390/50300338
Published: 22 March 2000
PDF Full-text (18 KB)
Open AccessAbstract Organic Cosolvent Effect on the Estimation of the Solubility of Oil Residues in Soil
Molecules 2000, 5(3), 340-341; doi:10.3390/50300340
Published: 22 March 2000
Cited by 1 | PDF Full-text (16 KB)
Abstract
The solubility in water and the partition coefficients, K, in soils samples of residues of petroleum of different ages were determined using an organic cosolvent (methanol), and the solvophobic theory was applied for the interpretation of results. The behavior of the residuals [...] Read more.
The solubility in water and the partition coefficients, K, in soils samples of residues of petroleum of different ages were determined using an organic cosolvent (methanol), and the solvophobic theory was applied for the interpretation of results. The behavior of the residuals turned out to be dependent of the cosolvent fraction. The values of K’s vary among 900 (Lkg-1) and 2,900 (Lkg-1) showing a general and marked increase for residues of increasing age. The determined parameters are useful for the modeling of environmental impact in polluted soils. Full article
Open AccessAbstract Preparation and Characterization of Solid Complexes of Naphtoquinone and Hydroxypropyl-b-Cyclodextrin
Molecules 2000, 5(3), 342-344; doi:10.3390/50300342
Published: 22 March 2000
Cited by 4 | PDF Full-text (19 KB)
Abstract The formation of an inclusion compound between a naphthoquinone derivative (I) and HP-ß-CD was studied in solid state by X-ray diffractometry, DSC, and IR. Full article
Open AccessAbstract Macrocyclic Trichothecene Production by the Fungus Epibiont of Baccharis Coridifolia
Molecules 2000, 5(3), 345-347; doi:10.3390/50300345
Published: 22 March 2000
PDF Full-text (20 KB)
Abstract Cultures of the fungus epibiont from the herbaceous shrub B. coridifolia yielded four macrocyclic trichothecenes. As these toxins are the same as those found in B. coridifolia, the relationship between the plant and the epibiont must be considered as mutualistic. Full article
Open AccessAbstract Sulfated Polyhydroxysteroids from the Antartic Ophiuroid Gorgonocephalus Chilensis
Molecules 2000, 5(3), 348-349; doi:10.3390/50300348
Published: 22 March 2000
Cited by 1 | PDF Full-text (18 KB)
Abstract Five disulfated steroids and a mixture of monosulfated steroids were isolated from the ethanolic extract of the antarctic ophiuroid Gorgonocephalus chilensis. The structures were determined by 1H-NMR, 13C-NMR and FABMS. Full article
Open AccessAbstract Labidiasteroside A, a Novel Saponin from the Antartic Starfish Labidiaster Annulatus
Molecules 2000, 5(3), 350-351; doi:10.3390/50300350
Published: 22 March 2000
Cited by 1 | PDF Full-text (18 KB)
Abstract Purification of the ethanolic extract of the starfish L. annulatus led to the isolation of two sulfated glycosides and a pentahydroxylated steroid. One of the saponins contains a novel pentasaccharide chain attached to C-6 of the steroidal aglycone. Full article
Open AccessAbstract Bioactive Steroidal Glycosides from the Starfish Anasterias Minuta
Molecules 2000, 5(3), 352-353; doi:10.3390/50300352
Published: 22 March 2000
PDF Full-text (14 KB)
Abstract Cytotoxic fractions obtained by purification of the ethanolic extract of Anasterias minuta contain sulfated hexasaccharide glycosides. These compounds show antifungal activity against Cladosporium cucumerinum. Full article
Open AccessAbstract Bioactive Metabolites Produced by Fungi Cultures
Molecules 2000, 5(3), 354-355; doi:10.3390/50300354
Published: 22 March 2000
Cited by 3 | PDF Full-text (15 KB)
Abstract A screening of metabolites guided by antimicrobial and citotoxic bioassays was conducted with several fungi. The bioactive compounds were isolated and identified from the active extracts. Full article
Open AccessAbstract Microbial Hydroxylation of Tedonodiol with Cultures of Aspergillus Niger
Molecules 2000, 5(3), 356-357; doi:10.3390/50300356
Published: 22 March 2000
Cited by 1 | PDF Full-text (16 KB)
Abstract Microbial hydroxylation of tedonodiol, an eremophilane alcohol, was carried out with Aspergillus niger cultures, yielding the 2α - hydroxyderivative. Full article
Open AccessAbstract Synthesis and Physicochemical Study of a Quinoxaline Derivative with Potencial Antineoplasic or Anti-HIV Activity
Molecules 2000, 5(3), 358-359; doi:10.3390/50300358
Published: 22 March 2000
PDF Full-text (13 KB)
Abstract Kinetics of the synthesis of 3-[3-quinoxaline(1H)-one]propionic acid (I) were performed. This compound was achieved from reaction between o-phenylenediamine and α-ketoglutaric acid under different experimental conditions, and it was sent to the National Cancer Institute (USA) for its pharmacological evaluation. Full article
Open AccessAbstract Effect of Substituents on the O-O Bond Rupture of Different Organic Peroxides in Toluene Solution
Molecules 2000, 5(3), 360-361; doi:10.3390/50300360
Published: 22 March 2000
PDF Full-text (15 KB)
Abstract The thermal decomposition reaction of cyclic organic peroxides was studied in toluene solution in a wide temperature range. The kinetic data show an important substituent effect on the unimolecular homolysis of the O-O bond of these molecules. Full article
Open AccessAbstract Thermal Decomposition Reaction of cis-6-Phenyl-5,6-(2-phenylpropilydene)-3,3-tetramethylene-1,2,4-trioxacyclohexane in Different Solvents
Molecules 2000, 5(3), 362-364; doi:10.3390/50300362
Published: 22 March 2000
Cited by 1 | PDF Full-text (16 KB)
Abstract The kinetics of the thermal decomposition reaction of cis-6-phenyl-5,6-(2-phenyl-propilydene)-3,3-tetramethylene-1,2,4-trioxacyclohexane (I) was investigated in the temperature range of 100-130°C in selected solvents of different physicochemical properties to evaluate a solvent effect on the reaction. Full article
Open AccessAbstract Thermal Decomposition Reaction of Acetophenone Cyclic Diperoxide in Solvents of Different Physicochemical Properties
Molecules 2000, 5(3), 365-366; doi:10.3390/50300365
Published: 22 March 2000
PDF Full-text (15 KB)
Abstract The thermal decomposition reaction of acetophenone cyclic diperoxide (trans-3,6-dimethyl-3,6-diphenyl-1,2,4,5-tetroxane; APDP) at the initial concentration of c.a. 0.01 mol kg-1 and temperature ranges of 135.5 to 185.0° C has been investigated in dioxane and acetonitrile solutions, and in an 2-propanol/benzene mixture. Full article
Open AccessAbstract Synthesis and Bioactivity of Teasterone and Typhasterol Analogs
Molecules 2000, 5(3), 367-369; doi:10.3390/50300367
Published: 22 March 2000
PDF Full-text (30 KB)
Abstract Four brassinosteroids analogs of homoteasterone and homotyphasterol bearing 5α-OH and 5α-F groups have been synthesized and their bioactivities evaluated. Full article
Open AccessAbstract Chemo- and Stereoselective Reduction of Polyfunctional Carbonyl Compounds by Mucor rouxii
Molecules 2000, 5(3), 370-371; doi:10.3390/50300370
Published: 22 March 2000
PDF Full-text (16 KB)
Abstract Several polyfunctional carbonyl compounds, such as α- and β-ketoesters, were chemo- and stereoselectively reduced by Mucor rouxii cultures in water and in organic solvents. Results show that reductions can be carried out in a variety of organic solvents. Full article
Open AccessAbstract Lipase-Catalyzed Polymerization of Glycerol and Dicarboxylic Acids in an Organic Medium
Molecules 2000, 5(3), 372-373; doi:10.3390/50300372
Published: 22 March 2000
Cited by 1 | PDF Full-text (17 KB)
Abstract Lipases from different sources catalyze the polyesterification of glycerol and several dicarboxylic acids in presence or organic solvents Full article
Open AccessAbstract Electrosynthesis of 3-Nitrophenotiazine. Nitration in Non-Aqueous Solutions
Molecules 2000, 5(3), 374-375; doi:10.3390/50300374
Published: 22 March 2000
PDF Full-text (16 KB)
Abstract
The nitration of Phenothiazine (PHEN) in acetonitrile (ACN) in the presence of excess NaNO2 has been studied in detail. First, the electrochemical behavior of the reactants was investigated by cyclic voltammetry to determine the electrolysis conditions. Controlledpotential electrolysis was used for [...] Read more.
The nitration of Phenothiazine (PHEN) in acetonitrile (ACN) in the presence of excess NaNO2 has been studied in detail. First, the electrochemical behavior of the reactants was investigated by cyclic voltammetry to determine the electrolysis conditions. Controlledpotential electrolysis was used for the electrosynthesis. Full article
Open AccessAbstract Chemical Characteristics of Passiflora Caerulea Sedd Oil and Residual Seed Meal
Molecules 2000, 5(3), 376-378; doi:10.3390/50300376
Published: 22 March 2000
PDF Full-text (18 KB)
Abstract
Seeds from Passiflora caerulea were defatted with n-hexane yielding 29,9% of crude oil (dry basis). The crude oil was examined in their physicochemical characteristics. Fatty acid composition value showed only three acids in significative proportion: 16:0, 18:1 and 18:2. The residual seed [...] Read more.
Seeds from Passiflora caerulea were defatted with n-hexane yielding 29,9% of crude oil (dry basis). The crude oil was examined in their physicochemical characteristics. Fatty acid composition value showed only three acids in significative proportion: 16:0, 18:1 and 18:2. The residual seed meal analysis included: moisture value, ash, metals content, sugars, crude fiber, protein and available lysine. Full article
Open AccessAbstract Photodynamic Effect Of 5,10,15,20-Tetrakis(4-Methoxyphenyl) Porphine (TMP) on Hep-2 Cell Lines
Molecules 2000, 5(3), 379-380; doi:10.3390/50300379
Published: 22 March 2000
Cited by 7 | PDF Full-text (16 KB)
Abstract The photodynamic effect of 5,10,15,20-tetrakis(4-methoxyphenyl)porphine (TMP) on Hep-2 cell line is reported. The incorporation of TMP was analyzed at different times and photosensitizer concentrations. The irradiation of cell cultures produces cell mortality, while no toxicity was observed in dark condition. Full article
Open AccessAbstract Synthesis and Characterization of Some N-Heterocyclic Carbohydrate Derivatives
Molecules 2000, 5(3), 381-382; doi:10.3390/50300381
Published: 22 March 2000
PDF Full-text (14 KB)
Abstract The nucleophilic bimolecular substitution on 1,2:3,4-di-O-isopropylidene-α-Dgalactopyranose with NH2-heterocyclic derivatives allows us to obtain some new compounds with potential biological activities. The characterization of them as well as a discussion of their reactivities toward sulfur analogues are present. Full article
Open AccessAbstract Synthesis and Characterization of Bent-rod Liquid Crystals
Molecules 2000, 5(3), 383-385; doi:10.3390/50300383
Published: 22 March 2000
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Abstract
Two series of diesters with bend-rod shapes were synthesized and their thermal properties characterized by POM and DSC. The central group conformational mobility and polarity as well as the length of the mesogenic groups were varied in order to correlate these parameters [...] Read more.
Two series of diesters with bend-rod shapes were synthesized and their thermal properties characterized by POM and DSC. The central group conformational mobility and polarity as well as the length of the mesogenic groups were varied in order to correlate these parameters with mesophase stability. Results indicate that series II diesters are enantiotropic and that their mesophase sensitivity to central group structural changes is limited. Full article
Open AccessAbstract Two New Labdane Diterpene Glycoside from Flowers of Bacchris Medulosa DC
Molecules 2000, 5(3), 386-387; doi:10.3390/50300386
Published: 22 March 2000
Cited by 1 | PDF Full-text (17 KB)
Abstract Two new labdane-type diterpene glycoside, were isolated from the flowers of Baccharis medulosa DC (Asteraceae). Structures of these compounds were established by application of various spectroscopic techniques. Full article
Open AccessAbstract Reactivity of β-Stannylketones. Elimination vs. Substitution
Molecules 2000, 5(3), 388-390; doi:10.3390/50300388
Published: 22 March 2000
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Abstract In the present work we report the results obtained in the reaction of β-stannylketones (I) with t-BuONa in dimethylsulfoxide (DMSO) and acetonitrile (ACN) as solvents. The reaction mechanisms probably involved are proposed. Full article
Open AccessAbstract Addition of Organotin Anions to α,β-Unsaturated Nitriles
Molecules 2000, 5(3), 391-392; doi:10.3390/50300391
Published: 22 March 2000
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Abstract The addition reaction of triorganotin anions to α,β-unsaturated nitriles leads to α-alkyl-β-stannylnitriles with high diastereoselectivity. Full article
Open AccessAbstract N,N-Diethyl-1-Tosyl-3-Indoleglyoxylamide as a Dienophile in Diels-Alder Reactions. Hyperbaric vs. Thermal Conditions
Molecules 2000, 5(3), 393-395; doi:10.3390/50300393
Published: 22 March 2000
Cited by 2 | PDF Full-text (20 KB)
Abstract Under high pressure conditions, the Diels-Alder reaction involving N,N-diethyl-1-tosyl-3-indoleglyoxylamide and 1-(N-acetyl-N-propylamino)-1,3-butadiene produces a highly functionalized intermediate for the synthesis of Indole Alkaloids, in shorter times and higher yields than under thermal conditions. Full article
Open AccessAbstract Synthesis of Poly(m-pyridylene-1,2-diphenylvinylene)
Molecules 2000, 5(3), 396-397; doi:10.3390/50300395
Published: 22 March 2000
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Abstract The synthesis by dehalogenating polycondensation and characterization of a new soluble conjugated polymer, poly(m-pyridylene-1,2-diphenylvinylene), DP-PPyV, is reported here. It shows good mechanical properties and a λmax = 330 nm. The maximum intensity peak of MALDI-TOF corresponds to 1.800 Da. Full article
Open AccessAbstract Structure-Fluorescence Relationships in Antimicrobial Fluoroquinolones (AMFQs)
Molecules 2000, 5(3), 398-400; doi:10.3390/50300398
Published: 22 March 2000
Cited by 1 | PDF Full-text (21 KB)
Abstract The analysis of fluorescence spectra of a set of structurally related AMFQ let to identify the effects of structural changes and the presence of electric charge generated by acid-base reaction on the emission spectra. Full article
Open AccessAbstract Reaction of 2,4-Dinitrochlorobenzene with Aromatic Amines in Toluene: Effect of Nucleophile Structure
Molecules 2000, 5(3), 401-402; doi:10.3390/50300401
Published: 22 March 2000
Cited by 2 | PDF Full-text (16 KB)
Abstract
The kinetics of the reaction of 2,4-dinitrochlorobenzene (DNClB) with aniline and substituted anilines such as p-anisidine, p-toluidine and N-methylaniline have been studied in toluene. Except for N-methylaniline the reactions have shown a third order in amine rate dependence which is consistent with [...] Read more.
The kinetics of the reaction of 2,4-dinitrochlorobenzene (DNClB) with aniline and substituted anilines such as p-anisidine, p-toluidine and N-methylaniline have been studied in toluene. Except for N-methylaniline the reactions have shown a third order in amine rate dependence which is consistent with aggregates of the amine acting as the nucleophile. On the other hand, the reaction of DNClB with N-methylaniline under the same conditions shows a linear dependence of the second order rate coefficient, kA, vs [amine], which is consistent with the previous mechanism. Full article
Open AccessAbstract 1-Nitronaphtalene as a Dienophile in Diels-Alder Reactions
Molecules 2000, 5(3), 403-404; doi:10.3390/50300403
Published: 22 March 2000
Cited by 1 | PDF Full-text (16 KB)
Abstract the utilization of substitued dienes with electron-donor groups and under high pressure conditions, induces the dienophilic character of 1-nitronaphtalene in Diels-Alder reactions, giving the products with and without the nitro-group, the yield depending on the nature of the dienes substituent groups. Full article
Open AccessAbstract Cyclodextrin Effect on Intramolecular Catalysis
Molecules 2000, 5(3), 405-406; doi:10.3390/50300405
Published: 22 March 2000
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Abstract
HPCD inhibits the hydrolysis reaction of monoamides and monoesters of phthalic and maleic acid at pH 2. The magnitude of inhibition depends on the leaving group. For some of the substrates, the reaction in the cavity is more than 100 times slower [...] Read more.
HPCD inhibits the hydrolysis reaction of monoamides and monoesters of phthalic and maleic acid at pH 2. The magnitude of inhibition depends on the leaving group. For some of the substrates, the reaction in the cavity is more than 100 times slower than that in solution. Full article
Open AccessAbstract Kinetic Study of the Hydrolisys of Phenyl Perfluorooctanoate in Water: Deaggregation Effect of b-Cyclodextrin
Molecules 2000, 5(3), 407-408; doi:10.3390/50300407
Published: 22 March 2000
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Abstract
The kinetics of the hydrolysis of phenyl perfluorooctanoate was studied at pH 6.00 and 9.90 in water. The substrate is aggregated under all working reaction conditions, which is indicated from the decrease in the reaction rate when the substrate concentration is raised. [...] Read more.
The kinetics of the hydrolysis of phenyl perfluorooctanoate was studied at pH 6.00 and 9.90 in water. The substrate is aggregated under all working reaction conditions, which is indicated from the decrease in the reaction rate when the substrate concentration is raised. The addition of β-cyclodextrin produces the deaggregation of the ester catalyzing the reaction. Full article
Open AccessAbstract Conformational Study of New AZT Derivatives
Molecules 2000, 5(3), 409-410; doi:10.3390/50300409
Published: 22 March 2000
Cited by 1 | PDF Full-text (16 KB)
Abstract A conformational study of three new AZT derivatives was made by semiempirical methods in order to find a structural correlation between these derivatives and AZT. Full article
Open AccessAbstract Computational Study of the Stereoselectivity of Diels-Alder Reactions of D-Glucose-Derived Dienophiles with Cyclopentadiene
Molecules 2000, 5(3), 411-412; doi:10.3390/50300411
Published: 22 March 2000
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Abstract A computational study was performed in order to rationalize the high exo stereoselectivity in the cycloaddition reactions of sugar-derived dienophiles with cyclopentadiene. Full article
Open AccessAbstract Comparative Study of Hydrocarbon, Fluorocarbon and Aromatic Bonded RP-HPLC Stationary Phases by Linear Solvation Energy Relationships
Molecules 2000, 5(3), 413; doi:10.3390/50300413
Published: 22 March 2000
Cited by 1 | PDF Full-text (12 KB)
Open AccessAbstract Cyclodimerization of Stilbenes and Styrenes Catalyzed by Heteropolyacid Supported on Silica
Molecules 2000, 5(3), 414-415; doi:10.3390/50300414
Published: 22 March 2000
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Abstract Several stilbenes and styrenes have been treated with heteropolyacid] (HPA) supported over silice. The compounds obtained were characterized by 1H and 13C- NMR and the yields were compared with those obtained using H2SO4 (c) and ethyl poliphosphate] (PPE). Full article
Open AccessAbstract Synthesis of Indanes Via a [3+2] Cycloaddition
Molecules 2000, 5(3), 416-417; doi:10.3390/50300416
Published: 22 March 2000
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Abstract The acid -promoted [3+2] cycloaddition of alkenes with benzhydrylic alcohols afford products in good yield and with remarkable stereoselectivity. Full article
Open AccessAbstract Synthesis of Heterocylic Compounds of Biological Interest from Carbohydrate Derivatives
Molecules 2000, 5(3), 418-419; doi:10.3390/50300418
Published: 22 March 2000
Cited by 1 | PDF Full-text (16 KB)
Abstract The synthesis of some isoxazolic compounds from carbohydrate derivatives is described. These products are obtained by 1,3-dipolar cycloaddition reaction and their functionalization leads to derivatives with potential biological activities. Full article
Open AccessAbstract Nuclear Magnetic Resonance for the Structural Study of Bioactive Semicarbazones
Molecules 2000, 5(3), 420-421; doi:10.3390/50300420
Published: 22 March 2000
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Abstract NMR studies of bioactive semicarbazones are described. Full article
Open AccessAbstract Antifeedant Activity Evaluation of Withanolides from Jaborosa integrifolia
Molecules 2000, 5(3), 422-423; doi:10.3390/50300422
Published: 22 March 2000
Cited by 2 | PDF Full-text (17 KB)
Abstract Antifeedant activity of the 4-deoxi-27-hydroxi-withanolides (1, 2 y 3) isolated from Jaborosa integrifolia (Solanaceae) was investigated in caterpillar Spodoptera littoralis on Leaf Disk Choice Bioassay. Results indicate that the best feed inhibition effect is due to Jaborosalactone A. Full article
Open AccessAbstract UV Spectral Properties of Benzophenone. Influence of Solvents and Substituents
Molecules 2000, 5(3), 424-425; doi:10.3390/50300424
Published: 22 March 2000
Cited by 5 | PDF Full-text (17 KB)
Abstract The effect of the solvent and the substituents on the UV spectroscopic properties of substituted benzophenones was studied. Full article
Open AccessAbstract Determination of the pKa of Benzophenones in Ethanol-Water
Molecules 2000, 5(3), 426-427; doi:10.3390/50300426
Published: 22 March 2000
Cited by 4 | PDF Full-text (16 KB)
Abstract The pKa of monohydroxylated benzophenones was determined by UV spectroscopy. The values obtained are coherent with the resonant forms and hydrogen bond intramolecular of the analyzed compounds. Full article
Open AccessAbstract Synthesis and In Vitro Antigungal Properties of 4-Aryl-4-Narylamine-1-butenes and Related Compounds
Molecules 2000, 5(3), 428-430; doi:10.3390/50300428
Published: 22 March 2000
Cited by 5 | PDF Full-text (24 KB)
Abstract A new series of 4-aryl and 4-alkyl-4-N-arylamine-1-butenes (homoallylamines) were synthesized and some of them transformed to 4-aryl or alkylquinolines. All of them showed strong antifungal activities against human pathogenic fungi in vitro, being Epidermophyton floccosum the most susceptible species. Full article
Open AccessAbstract SRN1 and Stille Reactions: A New Synthetic Strategy
Molecules 2000, 5(3), 431-432; doi:10.3390/50300431
Published: 22 March 2000
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Abstract
The photostimulated reaction of Me3Sn- ion with mono, di and trichloro arenes in liquid ammonia gave very good yields of stannanes by the SRN1 mechanism. These products reacted by a palladium-catalized cross coupling reaction with halobenzenes to [...] Read more.
The photostimulated reaction of Me3Sn- ion with mono, di and trichloro arenes in liquid ammonia gave very good yields of stannanes by the SRN1 mechanism. These products reacted by a palladium-catalized cross coupling reaction with halobenzenes to give phenylated products also in very goods yields. Similar yields can be obtained in one-pot reactions. Full article
Open AccessAbstract Citotoxic Activity of Extracts and Sesquiterpene Lactones from Stachycephalum argentinum
Molecules 2000, 5(3), 433-434; doi:10.3390/50300433
Published: 22 March 2000
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Abstract The extracts and sesquiterpene lactones of S.argentinum were assayed to determine their biological activity on Artemia salina. The most active compound was costunolide (1) with LD50= 62 ppm. Full article
Open AccessAbstract Phytotoxic Activity of a Benzofuran Isolated from Trichocline reptans
Molecules 2000, 5(3), 435-436; doi:10.3390/50300435
Published: 22 March 2000
Cited by 1 | PDF Full-text (14 KB)
Abstract
Phytotoxic Activity of the 6-acetyl-5-hydroxy-2isopropenyl-2,3-dihydrobenzofurane (1) isolated from Trichocline reptans (Asteraceae) was investigated in two weed species. Results indicate that the best growth inhibition effect ocurres on Chenopodium album weed. Phythotoxic effect of the T. reptans chloroformic extract and of [...] Read more.
Phytotoxic Activity of the 6-acetyl-5-hydroxy-2isopropenyl-2,3-dihydrobenzofurane (1) isolated from Trichocline reptans (Asteraceae) was investigated in two weed species. Results indicate that the best growth inhibition effect ocurres on Chenopodium album weed. Phythotoxic effect of the T. reptans chloroformic extract and of the benzofurane are discussed and compared in the two weed species. Full article
Open AccessAbstract Fluorimetric Determination of Carbamate Pesticides in Host-Guest Complexes
Molecules 2000, 5(3), 437-438; doi:10.3390/50300437
Published: 22 March 2000
Cited by 2 | PDF Full-text (18 KB)
Abstract
From the effect of β-cyclodextrin and hydroxypropyl-β-cyclodextrin on the UVvisible and fluorescence spectra of carbaryl and carbofuran, the values of association constants were determined. The ratio of the fluorescence quantum yields for the bound and free substrates indicated an enhanced fluorimetric method [...] Read more.
From the effect of β-cyclodextrin and hydroxypropyl-β-cyclodextrin on the UVvisible and fluorescence spectra of carbaryl and carbofuran, the values of association constants were determined. The ratio of the fluorescence quantum yields for the bound and free substrates indicated an enhanced fluorimetric method of detection. Full article
Open AccessAbstract Synthesis of Ethylenic and Acetylenic Triorganotins with Bulky Organic Ligands
Molecules 2000, 5(3), 439-440; doi:10.3390/50300439
Published: 22 March 2000
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Abstract
The syntheses of trineophyl- (1a) and tri-(-)-menthylstannyl phenylacetylene (1b) as well as that of (E)-1-trineophylestannyl-2-phenylethene (2) and (E)-1-trineophylstannyl-1,2-diphenylethene (3) are described. The hydrostannation of 1a with an excess of trimethyltin hydride led to 1,1,1-tris(trimethyltin)-2-phenylethane (4) and/or 1,1-bis(trimethyltin)-2-phenylethene (5) depending on the reaction [...] Read more.
The syntheses of trineophyl- (1a) and tri-(-)-menthylstannyl phenylacetylene (1b) as well as that of (E)-1-trineophylestannyl-2-phenylethene (2) and (E)-1-trineophylstannyl-1,2-diphenylethene (3) are described. The hydrostannation of 1a with an excess of trimethyltin hydride led to 1,1,1-tris(trimethyltin)-2-phenylethane (4) and/or 1,1-bis(trimethyltin)-2-phenylethene (5) depending on the reaction conditions. Full article
Open AccessAbstract New Spiranoid Withanolides From Jaborosa Odonelliana
Molecules 2000, 5(3), 441-442; doi:10.3390/50300441
Published: 22 March 2000
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Abstract From whole Jaborosa odonelliana plants four new withanolides containing a spiranic lactone in the side chain, were isolated and their structures elucidated by spectroscopic methods. Full article
Open AccessAbstract Synthesis of Aziridinosteroids
Molecules 2000, 5(3), 443-444; doi:10.3390/50300443
Published: 22 March 2000
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Abstract 11α,12α-aziridinosteroids (2a, b, c) were prepared from 5β-H-11-pregnene-3,20-dione (1) using different iminophenyliodinanes and cloramine aziridination reagents. Full article
Open AccessAbstract 3,3-Dimethylacylthioureas: "S", "-S", "U" or "W" Conformation?
Molecules 2000, 5(3), 445-446; doi:10.3390/50300445
Published: 22 March 2000
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Abstract
We report a study of 3,3-dimethyl substituted acylthioureas. X ray data and quantum mechanical calculations demonstrated that the "S" conformation is the most stable both for the acylthioureas and the corresponding anions. The high regioselectivity towards S-alkylation is explained on the basis [...] Read more.
We report a study of 3,3-dimethyl substituted acylthioureas. X ray data and quantum mechanical calculations demonstrated that the "S" conformation is the most stable both for the acylthioureas and the corresponding anions. The high regioselectivity towards S-alkylation is explained on the basis of the localization of the HOMO mainly over the sulfur atom. Full article
Open AccessAbstract Synthesis of D-Homo Analogs of Neurosteroids
Molecules 2000, 5(3), 447-448; doi:10.3390/50300447
Published: 22 March 2000
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Abstract 17(13→18)-Abeo and D-homo analogs of the natural neurosteroid 3α-hydroxy-5αH-pregnan-20-one were prepared by anionic or radical (mercury (II) hydride mediated) rearrangements of steroidal cyclopropylketones respectively. Full article
Open AccessAbstract A New Rearranged Non-Aromatic Salpichrolide from Salpichroa Origanifolia
Molecules 2000, 5(3), 449-450; doi:10.3390/50300449
Published: 22 March 2000
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Abstract From the aerial parts of Salpichroa origanifolia a new withanolide in which the C-13 angular methyl has migrated to C-17, was isolated and characterized by spectroscopic methods. Full article
Open AccessAbstract Reactivity Comparison of D–Glucose–Derived Dienophiles. Analysis of the Conformational and Electronic Properties
Molecules 2000, 5(3), 451-452; doi:10.3390/50300451
Published: 22 March 2000
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Abstract Semiempirical calculations were performed to carry out a conformational analysis for carbohydrate-derived dienophiles 1-4. For α,β-unsaturated carbonylic compounds 2-4, a good correlation between Diels-Alder reactivity with calculated values for LUMO energies was observed. Full article
Open AccessAbstract Teorethical Studies of the Stability of 8a-Alkyll-1,2,3,4,6,8ahexahydronaphtalen-1-ones Using Semiempirical Methods
Molecules 2000, 5(3), 453-454; doi:10.3390/50300453
Published: 22 March 2000
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Abstract The Birch alkylation products are very unstable. We are showing, in this communication, the results of a theoretical study that compares different decomposition reaction mechanisms. The conclusions are in agreement with our experimental results. Full article
Open AccessAbstract Photochemical Study of the Reactions of the 2-Naphtoxide Ion with Haloadamantanes
Molecules 2000, 5(3), 455-456; doi:10.3390/50300455
Published: 22 March 2000
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Abstract
The fluorescent excited state of 2-naphtoxide ion is quenched by haloadamantanes (X-Ada) as electron acceptors according to an electron-transfer mechanism. This mechanism is proposed on the basis of:1) decreasing quenching rate constant as the reduction potential of X-Ada is made more negative [...] Read more.
The fluorescent excited state of 2-naphtoxide ion is quenched by haloadamantanes (X-Ada) as electron acceptors according to an electron-transfer mechanism. This mechanism is proposed on the basis of:1) decreasing quenching rate constant as the reduction potential of X-Ada is made more negative and 2) the analysis of reaction products. Full article
Open AccessAbstract A Different Behaviour of the Phthalimide Ion in Srn1 Reactions
Molecules 2000, 5(3), 457-458; doi:10.3390/50300457
Published: 22 March 2000
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Abstract The phthalimide anion reacts by the SRN1 mechanism under photostimulation with different substrates. Whilst with 1-iodonaphthalene only reduction of the naphthyl radical is observed, with 1-iodoadamantane coupling at the carbon instead of at the nitrogen takes place. Full article
Open AccessAbstract Variation in the Composition of the Essential Oil of Senecio Filaginoides Dc
Molecules 2000, 5(3), 459-461; doi:10.3390/50300459
Published: 22 March 2000
Cited by 4 | PDF Full-text (20 KB)
Open AccessAbstract Gastric Cytoprotective Activity of Ilicic Aldehyde in Rats and Mice
Molecules 2000, 5(3), 462-464; doi:10.3390/50300462
Published: 22 March 2000
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Abstract Ilicic alcohol, a natural sesquiterpene, was converted into an aldehyde by using Jones’ oxidation. The gastroprotective activity of ilicic aldehyde was evaluated in mice and rats. Full article
Open AccessAbstract Chemical Components and Biological Activity of Bidens Subalternans, B. Aurea (Astereaceae) and Zuccagnia Puntacta (Fabaceae)
Molecules 2000, 5(3), 465-467; doi:10.3390/50300465
Published: 22 March 2000
Cited by 2 | PDF Full-text (19 KB)
Abstract The aim of this work was to evaluate the activity in the gastrointestinal tract of the several extracts and pure components isolated from Bidens species and Zuccagnia puntacta. Full article
Open AccessAbstract Regioselective Opening of Epoxides Catalyzed by Sn (IV). A New Method for the Synthesis of Halohydrins?
Molecules 2000, 5(3), 468-469; doi:10.3390/50300468
Published: 22 March 2000
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Abstract The regioselective opening of epoxides with organotin oxides 1 and 2, in presence of halogenated alcohols was developed, yielding the halohydrin derivatives. Full article
Open AccessAbstract Phytochemical Study of Condalia microphylla Cav.
Molecules 2000, 5(3), 470-471; doi:10.3390/50300470
Published: 22 March 2000
Cited by 2 | PDF Full-text (15 KB)
Abstract From the petroleum ether extract of the aereal part of Condalia microphylla Cav, hydrocarbons, sterols, alcohols, and fatty acids were isolated. From fruits of the same plant anthocyanins were also isolated and characterized by chromatographic and spectroscopic methods. Full article
Open AccessAbstract Isomerisation of Methyl (E) 2-Bromo-3-(4-XC6H4)-propenoates
Molecules 2000, 5(3), 472-474; doi:10.3390/50300472
Published: 22 March 2000
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Abstract The geometric isomerisation of the title compound induced by bromine or chlorine appears to involve ionic pair species resulting from the nucleophilic attack of the halogen. Full article
Open AccessAbstract Lipoxygenase-1 Activity of Soybean Genotypes Grown in Argentina
Molecules 2000, 5(3), 475-478; doi:10.3390/50300475
Published: 22 March 2000
Cited by 1 | PDF Full-text (21 KB)
Abstract
The lipoxygenase-1 (LOX-1) activity of 19 soybean genotypes was quantified in two consecutive years. The LOX-1 activity produced by any cultivar was essentially the same in both, 1995 and 1996 crop years. The lowest values of LOX-1 activity were found in NK [...] Read more.
The lipoxygenase-1 (LOX-1) activity of 19 soybean genotypes was quantified in two consecutive years. The LOX-1 activity produced by any cultivar was essentially the same in both, 1995 and 1996 crop years. The lowest values of LOX-1 activity were found in NK 555 cultivar whereas Asgrow 5409 cultivar had the highest values. Full article
Open AccessAbstract 1H and 13C-NMR Spectroscopic Study of Some 1H-4,5-Dihydroimidazolium Salts
Molecules 2000, 5(3), 479-480; doi:10.3390/50300479
Published: 22 March 2000
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Abstract The 1H y 13C-NMR spectra of some 1,3 and 1,2,3-trisubstituted 1H-4,5-dihydroimidazolium salts are analyzed. Full article
Open AccessAbstract Improved Synthesis of N-Substituted Quinolinimides Using Microwave Irradiation
Molecules 2000, 5(3), 481-482; doi:10.3390/50300481
Published: 22 March 2000
Cited by 1 | PDF Full-text (17 KB)
Abstract The synthesis of several quinolinimidoacetic acid derivatives (I) by two different routes, starting from quinolinic anhydride or quinolinimide, is described. In all cases better yields and decreased reaction times were achieved employing microwave irradiation as an alternative source of energy. Full article
Open AccessAbstract Conformational Analysis of Seven Membered Nitrogen Heterocycles Employing Molecular Modeling. Part II: 1-(ONitrophenyl)-2-Phenyl-1h-4,5,6,7-Tetrahydro-1,3-Diazepine
Molecules 2000, 5(3), 483-484; doi:10.3390/50300483
Published: 22 March 2000
Cited by 1 | PDF Full-text (15 KB)
Abstract Geometry optimization of 1-(o-nitrophenyl)-2-phenyl-1H-4,5,6,7-tetrahydro-1,3-diazepine is performed by means of molecular modeling. Results are correlated with theoretical and experimental UV spectra. Full article
Open AccessAbstract New Peanut Product: “Mayonnaise”. Some Chemical Aspects
Molecules 2000, 5(3), 485-486; doi:10.3390/50300485
Published: 22 March 2000
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Abstract The percentage composition, fatty acids and oxidation stability was obtained from “peanut mayonnaise” in comparison with commercial mayonnaise and sunflower oil. “Peanut mayonnaise” showed better chemical quality than commercial mayonnaise. Full article
Open AccessAbstract Antioxidant Activity of Methanolic Extracts from Peanut Skin
Molecules 2000, 5(3), 487-488; doi:10.3390/50300487
Published: 22 March 2000
Cited by 4 | PDF Full-text (16 KB)
Abstract
Antioxidant activity of skin from runner peanut was performed on sunflower refined oil. The skin was obtained from industrial blanching process. The oil was oxidized at 60ºC. The methanolic extracts show antioxidant activity in relation to the oil (without additives). However these [...] Read more.
Antioxidant activity of skin from runner peanut was performed on sunflower refined oil. The skin was obtained from industrial blanching process. The oil was oxidized at 60ºC. The methanolic extracts show antioxidant activity in relation to the oil (without additives). However these extracts do not reach the activity level from BHT. Full article
Open AccessAbstract Relationship Between the Conformation of the Cyclopeptides Isolated from the Fungus Amanita Phalloides (Vaill. Ex Fr.) Secr. and Its Toxicity
Molecules 2000, 5(3), 489-490; doi:10.3390/50300489
Published: 22 March 2000
Cited by 1 | PDF Full-text (17 KB)
Abstract The electronic structures and conformational studies of the cyclopeptides, Omethyl-α-amanitin, phalloidin and antamanide, were obtained from molecular parameters on the basis of semiempiric and ab initio methods. Full article
Open AccessAbstract Synthetic Studies on Natural Stephaoxocanes. Elaboration of a Tetrahydrooxazaphenalene Potential Intermediate
Molecules 2000, 5(3), 491-492; doi:10.3390/50300491
Published: 22 March 2000
Cited by 1 | PDF Full-text (20 KB)
Abstract The elaboration of a 2,3,7-9a-tetrahydro-1H-8-oxa-1-aza-phenalen-9-one derivative, as a potential key intermediate for the synthesis of stephaoxocanes, employing Jackson’s tosylamidoacetal cyclization, is presented. Full article
Open AccessAbstract Elaboration of the Isochromane System of Stephaoxocanes Employing an Oxa-Pictet Spengler Type Cyclization
Molecules 2000, 5(3), 493-494; doi:10.3390/50300493
Published: 22 March 2000
Cited by 3 | PDF Full-text (21 KB)
Abstract An approach to the synthesis of the isochromane moiety embodying the AC-ring system of the stephaoxocanes, by the use of an Oxa-Pictet Spengler type cyclization strategy, is reported. Full article
Open AccessAbstract Practical and Efficient Procedure for the In Situ Preparation of B-Alkoxyoxazaborolidines. Enantioselective Reduction of Prochiral Ketones
Molecules 2000, 5(3), 495-496; doi:10.3390/50300495
Published: 22 March 2000
Cited by 2 | PDF Full-text (16 KB)
Abstract A new method for the in situ elaboration of B-alkoxyoxazaborolidines is presented. Their use in the enantioselective reduction of prochiral aromatic ketones provides excellent chemical and optical yields of chiral alcohols. Full article
Open AccessAbstract Synthetic Modifications of Lead Compounds as Antitrypanosomal Drugs
Molecules 2000, 5(3), 497-498; doi:10.3390/50300497
Published: 22 March 2000
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Abstract Following our work in the synthesis of compounds with antichagasic activity, we describe new potential products in which the same "leader" compound was modulated. Full article
Open AccessAbstract Synthesis of 1,2,6-Thiadiazin 1,1-Dioxide Derivatives as Trypanocidal Agents
Molecules 2000, 5(3), 499-500; doi:10.3390/50300499
Published: 22 March 2000
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Abstract It describes the synthesis of new 1,2,6-Thiadiazin 1,1-dioxide derivatives using condensation of the Knoevenagel type. The products are evaluated in vitro as trypanocidal agents. Full article
Open AccessAbstract Reactivity Studies of 5,6-Dimethyl- and 3,5,6-Trimethyl -1,2,4-Triazine–N4-Oxide Against Different Electrophiles
Molecules 2000, 5(3), 501-502; doi:10.3390/50300501
Published: 22 March 2000
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Abstract It describes the regioselectivity studies of 5,6-Dimethyl-1,2,4-triazine-N4-oxide using different electrophiles. Full article
Open AccessAbstract Addition of Aromatic Nucleophiles to a C=N Double Bond of 1,2,5-Thiadiazole 1,1-Dioxide
Molecules 2000, 5(3), 503-504; doi:10.3390/50300503
Published: 22 March 2000
Cited by 2 | PDF Full-text (15 KB)
Abstract A new synthesis of 3,4-diphenyl-4-aryl-1,2,5-thiadiazolines 1,1-dioxide through the addition of aromatic derivatives to 1,2,5-thiadiazole 1,1-dioxide is presented. Anhydrous AlCl3 is used as catalyst. Full article
Open AccessAbstract Studies on a New Synthetic Route towards Cassiol
Molecules 2000, 5(3), 505-507; doi:10.3390/50300505
Published: 22 March 2000
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Abstract The synthesis of the acyclic intermediate 7 towards the preparation of cassiol (2) is described. The cyclization of 7 led to 5, a precursor of 2 and to the unexpected product 8. Full article
Open AccessAbstract Synthesis and Characterization of New Naphthoquinonic Derivatives Containing the Pyrazole Ring: Pyrazolylnaphthoquinones
Molecules 2000, 5(3), 508-509; doi:10.3390/50300508
Published: 22 March 2000
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Abstract The reaction of 3-aminopyrazole (1) with 1,2-naphthoquinone-4-sulfonic acid sodium salt (2) was studied in different aqueous media. The novel pyrazolylnaphthoquinones synthesized were physical and spectroscopically characterized, including 2D NMR spectroscopy (HETCOR). The possible reaction mechanism is proposed. Full article
Open AccessAbstract Determination of the Formation Constant of the Inclusion Complex from a Naphthoquinone
Molecules 2000, 5(3), 510-511; doi:10.3390/50300510
Published: 22 March 2000
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Abstract Inclusion complexation of 1 with HP-β-CD or HP-β-CD:PVP K30 in aqueous solution was spectroscopically studied and the formation constant for a 1:1 complex was determined from these measurements. Full article
Open AccessAbstract Binding Constant of Amines to Water/AOT/n-Hexene Reverse Micelles. Influence of the Chemical Structure
Molecules 2000, 5(3), 512-513; doi:10.3390/50300512
Published: 22 March 2000
Cited by 1 | PDF Full-text (15 KB)
Abstract
The distribution of different amines between n-hexane bulk and the micellar pseudophase of AOT reverse micelles were measured by a fluorometric method. An independent method was used to corroborate the incorporation of the amines to the interface. The effect of the amine [...] Read more.
The distribution of different amines between n-hexane bulk and the micellar pseudophase of AOT reverse micelles were measured by a fluorometric method. An independent method was used to corroborate the incorporation of the amines to the interface. The effect of the amine structure on the binding constant was analysed. Full article
Open AccessAbstract New Withanolides from Two Varieties of Jaborosa Caulescens
Molecules 2000, 5(3), 514-515; doi:10.3390/50300514
Published: 22 March 2000
Cited by 1 | PDF Full-text (17 KB)
Abstract
The phytochemical study of two species of Jaborosa caulescens (var. caulescens and var. bipinnatifida) yielded the four new withanolides 1-4. The structures of the new compounds were determined using a combination of spectroscopic techniques (including 1D and 2D NMR) and [...] Read more.
The phytochemical study of two species of Jaborosa caulescens (var. caulescens and var. bipinnatifida) yielded the four new withanolides 1-4. The structures of the new compounds were determined using a combination of spectroscopic techniques (including 1D and 2D NMR) and Molecular Modeling. Full article
Open AccessAbstract Formation of Complexes of Flavonoids and Metals. Determination of the Stoichiometry and Stability Constants
Molecules 2000, 5(3), 516-517; doi:10.3390/50300516
Published: 22 March 2000
Cited by 4 | PDF Full-text (14 KB)
Abstract The complexes between some flavonoids and metals (Co(II), Cu(II), Mn(II), Mg(II), Sn(II)) have been studied by spectrophotometric methods in order to determine the stoichiometry and stability constants. Full article
Open AccessAbstract Analysis by Mass Spectrometry of the Polar Lipids from the Cellular Membrane of Thermophilic Lactic Acid Bacteria
Molecules 2000, 5(3), 518-519; doi:10.3390/50300518
Published: 22 March 2000
Cited by 1 | PDF Full-text (16 KB)
Abstract
Fast atom bombardment (FAB) technique was employed to determine the structure of polar lipids from the cellular membrane of Lactobacillus delbruekii ssp. bulgaricus and Streptococcus salivarius ssp. thermophilus. Analysis of spectra provided useful information about the molecular species and aminoacids constituents [...] Read more.
Fast atom bombardment (FAB) technique was employed to determine the structure of polar lipids from the cellular membrane of Lactobacillus delbruekii ssp. bulgaricus and Streptococcus salivarius ssp. thermophilus. Analysis of spectra provided useful information about the molecular species and aminoacids constituents of the samples. Full article
Open AccessAbstract Chemical Modifications of 1,2,5-Oxadiazole N-Oxide System Searching for Cytotoxic Selective Hypoxic Drugs
Molecules 2000, 5(3), 520-521; doi:10.3390/50300520
Published: 22 March 2000
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Abstract New analogues of 3-Formyl-4-phenyl-1,2,5-oxadiazole N-oxide (1) are prepared and evaluated as cytotoxic selective agents in hypoxia. Full article
Open AccessAbstract Approach to the A-B Ring System of Forskolin through Biotransformation of Toluene
Molecules 2000, 5(3), 522-523; doi:10.3390/50300522
Published: 22 March 2000
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Abstract
In the present work, we will intend to show that diol I, microbially derived from toluene using Pseudomonas putida 39D, is a suitable synthon for the synthesis of the A-B ring system of forskolin. The functionalization of diol I, to be used [...] Read more.
In the present work, we will intend to show that diol I, microbially derived from toluene using Pseudomonas putida 39D, is a suitable synthon for the synthesis of the A-B ring system of forskolin. The functionalization of diol I, to be used as ring-B, and the attempts of ring-A closure, will be disclosed. Full article
Open AccessAbstract Shelf-Life of an Extruded Blend of Peanut, Soybean and Corn
Molecules 2000, 5(3), 524-525; doi:10.3390/50300524
Published: 22 March 2000
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Abstract
The Shelf-Life (SL) of peanut, soybean and corn blend extruded without (A) and with butylhydroxytoluol (B) and extract of Rosmarinum sp (C) was determined. Only B significativaly increased SL. In function of temperature would be defined by: A- SL = e -0.0465x [...] Read more.
The Shelf-Life (SL) of peanut, soybean and corn blend extruded without (A) and with butylhydroxytoluol (B) and extract of Rosmarinum sp (C) was determined. Only B significativaly increased SL. In function of temperature would be defined by: A- SL = e -0.0465x + 5.1762, B- SL = e -0.0421x + 5.3332, C- SL = e -0.581x +5.626 Full article
Open AccessAbstract A Facile High-Yield Synthesis of [10 B]-8-Dihydroxyboryl Harmine, a Potential Agent for Boron Neutron Capture Therapy
Molecules 2000, 5(3), 526-528; doi:10.3390/50300526
Published: 22 March 2000
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Open AccessAbstract Synthesis of Diads and Triads Derived from Carotenoids and Fullerene C60
Molecules 2000, 5(3), 529-530; doi:10.3390/50300529
Published: 22 March 2000
Cited by 2 | PDF Full-text (16 KB)
Abstract A convenient procedure for the synthesis of supramolecules bearing carotenoids and fullerene C60 is reported. The amphipathic nature and the high yield of charge separation of these compounds make them candidates in the formation of transmembrane charge gradients. Full article
Open AccessAbstract Synthesis of Asymmetrical Porphyrins Substituted in the meso-Position from Dipyrrolomethanes
Molecules 2000, 5(3), 531-532; doi:10.3390/50300531
Published: 22 March 2000
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Abstract A convenient procedure for the synthesis of 5-(4-acetamidophenyl)-10,15,20-tris(4-substituted phenyl) porphyrins from dipyrrolomethane is reported. meso-(4-Substituted phenyl) dipyrrolomethanes were obtained in yields of 72-84%. The amide porphyrins were isolated with appreciable yields of 15-17%. Full article
Open AccessAbstract A Simple Enzymatic Preparation of 2’,3’-Di-OAcetylnucleosides Through a Lipase Catalyzed Alcoholysis
Molecules 2000, 5(3), 533-534; doi:10.3390/50300533
Published: 22 March 2000
Cited by 3 | PDF Full-text (15 KB)
Abstract Several 2’,3’-di-O-acetylnucleosides (2a-d) were obtained regioselectively through a Candida antarctica B lipase catalyzed alcoholysis. Full article
Open AccessAbstract Escherichia Coli Bl21: A Useful Biocatalyst for the Synthesis of Purine Nucleosides
Molecules 2000, 5(3), 535-536; doi:10.3390/50300535
Published: 22 March 2000
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Abstract
E. coli BL21 cells were able to synthesize several purine nucleosides from pyrimidine ones. Kinetics and yields of this reaction showed a strong dependence on pH, temperature, reagent concentrations and weight of wet cell paste. Yields over 90% were reached in the [...] Read more.
E. coli BL21 cells were able to synthesize several purine nucleosides from pyrimidine ones. Kinetics and yields of this reaction showed a strong dependence on pH, temperature, reagent concentrations and weight of wet cell paste. Yields over 90% were reached in the synthesis of adenosine. Full article
Open AccessAbstract Solid-Phase Organic Chemistry: Synthesis of 2β-(Heterocyclylthiomethyl)Penam Derivatives on Solid Support
Molecules 2000, 5(3), 537-538; doi:10.3390/50300537
Published: 22 March 2000
Cited by 1 | PDF Full-text (31 KB)
Abstract The synthesis of 2β-(heterocyclylthiomethyl)penam derivatives on solid support has been developed. Compounds are obtained in good to high yields (based on loading of the original resin). The key step is the solid-phase double rearrangement of the corresponding penicillin sulfoxide. Full article
Open AccessAbstract Stereoelectronic Contributions to 1H-1H Coupling Constants
Molecules 2000, 5(3), 539-540; doi:10.3390/50300539
Published: 22 March 2000
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Abstract
The effect of stereoelectronic interactions on coupling constants is shown. The analysis is done with a new approach in which a selected interaction is deleted and the effect over the couplings is analyzed. 1H-1H magnetic couplings three and four [...] Read more.
The effect of stereoelectronic interactions on coupling constants is shown. The analysis is done with a new approach in which a selected interaction is deleted and the effect over the couplings is analyzed. 1H-1H magnetic couplings three and four bonds apart in hydrocarbons are shown. Full article
Open AccessAbstract Alkali Treatment of the Polysaccharides from the Cystocarpic Stage from Iridaea Undulosa
Molecules 2000, 5(3), 541-542; doi:10.3390/50300541
Published: 22 March 2000
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Abstract
The polysaccharides from cystocarpic Iridaea undulosa, soluble and insoluble in 2M potassium chloride, Cs and Ci, respectively, were treated with alkali and fractionated by precipitation with increasing concentrations of KCl. They were later separated by ionexchange chromatography, to yield fractions enriched [...] Read more.
The polysaccharides from cystocarpic Iridaea undulosa, soluble and insoluble in 2M potassium chloride, Cs and Ci, respectively, were treated with alkali and fractionated by precipitation with increasing concentrations of KCl. They were later separated by ionexchange chromatography, to yield fractions enriched in an α-(1→6)-glucan, agaroids and carrageenans. Full article
Open AccessAbstract The 75% Isopropanol-Soluble Polysaccharides from the Endosperm of the Legume Seed of Gleditsia Triacanthos
Molecules 2000, 5(3), 543-544; doi:10.3390/50300543
Published: 22 March 2000
Cited by 2 | PDF Full-text (15 KB)
Abstract The 75% isopropanol-soluble material from the endosperm of the legume-seed of Gleditsia triacanthos was isolated. The material extracted with boiling water was fractionated by ion-exchange chromatography and characterized. Besides minor amounts of galactomannans, major proportions of arabinans and/or arabinogalactans appear. Full article
Open AccessAbstract Studies of Lipids and Proteins in a Wild Species of the Arachis (Fabaceae) Gender
Molecules 2000, 5(3), 545-546; doi:10.3390/50300545
Published: 22 March 2000
Cited by 1 | PDF Full-text (15 KB)
Abstract
Chemical components of eight wild species of Arachis were studied. The objectives were to know the chemical composition and establish chemotaxonomic relationships. The results indicate that A. villosa is suitable for breeding program of cultivated peanut. A. monticola and A. batizocoi showed [...] Read more.
Chemical components of eight wild species of Arachis were studied. The objectives were to know the chemical composition and establish chemotaxonomic relationships. The results indicate that A. villosa is suitable for breeding program of cultivated peanut. A. monticola and A. batizocoi showed major chemical affinity with A. hipogaea. Full article
Open AccessAbstract Antiinflammatory Activity of Cinnamic Acid Esters
Molecules 2000, 5(3), 547-548; doi:10.3390/50300547
Published: 22 March 2000
Cited by 4 | PDF Full-text (16 KB)
Abstract The cinnamate esters of 3-p-menthanol (trivial name, menthol) (1) and 4(8)-pmenthen-3-ol (trivial name, pulegol) (2) were prepared and their anti-inflammatory activity was measured. Some of the monoterpenoid esters displayed interesting anti-inflammatory activity. Full article
Open AccessAbstract Use of Cyclic Di- and Triperoxides as Initiators of Styrene Polymerization at High Temperature with a View to Their Use in Industrial Applications
Molecules 2000, 5(3), 549-550; doi:10.3390/50300549
Published: 22 March 2000
Cited by 3 | PDF Full-text (15 KB)
Abstract
In industry, the bulk free radical polymerization of styrene takes place with the aid of peroxide initiators such as benzoyl peroxide. In this work di- and trimeric cyclic peroxides were used as initiators of the styrene polymerization in order to increase the [...] Read more.
In industry, the bulk free radical polymerization of styrene takes place with the aid of peroxide initiators such as benzoyl peroxide. In this work di- and trimeric cyclic peroxides were used as initiators of the styrene polymerization in order to increase the rate of polymerization and molecular weights simultaneously. Full article
Open AccessAbstract Polisaccharides from Cystocarpic Plants of the Red Seaweed Callophyllis Variegata
Molecules 2000, 5(3), 551-552; doi:10.3390/50300551
Published: 22 March 2000
Cited by 3 | PDF Full-text (15 KB)
Abstract
The crude polysaccharide from cystocarpic Callophyllis variegata was fractionated with potassium chloride yielding three minor fractions which precipitated between 0.05-0.10 M KCl, 1.20-1.25 M KCl and 1.80-2.00 M KCl, and a main product soluble in 2.00 M KCl. These fractions were analysed [...] Read more.
The crude polysaccharide from cystocarpic Callophyllis variegata was fractionated with potassium chloride yielding three minor fractions which precipitated between 0.05-0.10 M KCl, 1.20-1.25 M KCl and 1.80-2.00 M KCl, and a main product soluble in 2.00 M KCl. These fractions were analysed and structural analysis of the major one was carried out by methylation, FT-IR and 13C NMR. Full article
Open AccessAbstract Comparison Between Aqueous and Nonaqueous AOT-Heptane Reverse Micelles Using Acridine Orange as Molecular Probe
Molecules 2000, 5(3), 553-554; doi:10.3390/50300553
Published: 22 March 2000
Cited by 2 | PDF Full-text (16 KB)
Abstract
Aqueous and nonaqueous AOT/n-heptane reverse micelles where characterized by UV-Visible and fluorescence spectroscopy of AO. The study shows the presence of the dimer in aqueous reverse micelles which is not present in the nonaqueous systems. It seems that there is a conversion [...] Read more.
Aqueous and nonaqueous AOT/n-heptane reverse micelles where characterized by UV-Visible and fluorescence spectroscopy of AO. The study shows the presence of the dimer in aqueous reverse micelles which is not present in the nonaqueous systems. It seems that there is a conversion of the dimer to monomer in the aqueous reverse micelles at high AOT concentration. In the nonaqueous systems, there is only partition of the monomer. The apparent constants of these processes were calculated. Full article
Open AccessAbstract Synthesis of a Thienothiophene Conjugated Polymer
Molecules 2000, 5(3), 555-556; doi:10.3390/50300555
Published: 22 March 2000
Cited by 3 | PDF Full-text (17 KB)
Abstract
A new conducting polymer was prepared by chemical and electrochemical polymerization of 3,6-dimethylthieno[3,2-b]thiophene. The galvanostatic deposition afforded uniform, adherent and dark blue films of PDMTT. Electrochemical characterization by cyclic voltammetry showed that it can be repeatedly driven between the doped and undoped [...] Read more.
A new conducting polymer was prepared by chemical and electrochemical polymerization of 3,6-dimethylthieno[3,2-b]thiophene. The galvanostatic deposition afforded uniform, adherent and dark blue films of PDMTT. Electrochemical characterization by cyclic voltammetry showed that it can be repeatedly driven between the doped and undoped species with a coulombic efficiency of nearly 100%. Full article
Open AccessAbstract Integral Chemical Analysis of the Amaranth (Amaranthus greggii S. Wats)
Molecules 2000, 5(3), 557-559; doi:10.3390/50300559
Published: 22 March 2000
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Abstract
The objective of this work was to obtain information on Amaranthus greggii S. Wats., related to its nutritional value, its agricultural application as leaf vegetable and for animal consumption. The following variables were analyzed: dampness, ashes, protein, mineral, ethereal extract (fat), brute [...] Read more.
The objective of this work was to obtain information on Amaranthus greggii S. Wats., related to its nutritional value, its agricultural application as leaf vegetable and for animal consumption. The following variables were analyzed: dampness, ashes, protein, mineral, ethereal extract (fat), brute fiber, oxalic acid, nitrates and carbohydrates. Full article
Open AccessAbstract Catalytic Activity of MEL Zeolites Modified with Metallic Couples for the Conversion of Ethane
Molecules 2000, 5(3), 560-561; doi:10.3390/50300560
Published: 22 March 2000
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Abstract
The transformation of ethane into aromatic hydrocarbons over Zn-metal- containing zeolites at W/F=10 gh/mol and 550°C was studied in a flow reactor at atmospheric pressure. Zn-metal-zeolite modified the activation mode of the alkane, generating highly reactive intermediates and enhancing the aromatic selectivity. [...] Read more.
The transformation of ethane into aromatic hydrocarbons over Zn-metal- containing zeolites at W/F=10 gh/mol and 550°C was studied in a flow reactor at atmospheric pressure. Zn-metal-zeolite modified the activation mode of the alkane, generating highly reactive intermediates and enhancing the aromatic selectivity. Full article
Open AccessAbstract A Simple Method for N-Phenoxyethylation of Anilines
Molecules 2000, 5(3), 562-563; doi:10.3390/50300562
Published: 22 March 2000
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Abstract
We wanted to search for new reaction conditions to prepare the title compounds, to be checked later in novel syntheses of heterocyclic compounds. To the best of our knowledge, there was no report in the literature of any well-established method for the [...] Read more.
We wanted to search for new reaction conditions to prepare the title compounds, to be checked later in novel syntheses of heterocyclic compounds. To the best of our knowledge, there was no report in the literature of any well-established method for the preparation of N-(2-phenoxyethyl)anilines 1. Full article
Open AccessAbstract First Synthesis of (20S) 3β,16β-Dihydroxy-5-pregnen-20,16-carbolactone (Diosgeninlactone)
Molecules 2000, 5(3), 564-565; doi:10.3390/50300564
Published: 22 March 2000
Cited by 2 | PDF Full-text (17 KB)
Abstract Diosgeninlactone (1), a natural product from Solanum vespertilio, was stereoselectively synthesized in high yield from 3β-hydroxy-5-androstene. Full article
Open AccessAbstract Separation of the Pigment of an Amaranth
Molecules 2000, 5(3), 566-567; doi:10.3390/50300566
Published: 22 March 2000
PDF Full-text (14 KB)
Abstract
It is known that current quality requirements require the utilization of natural colorants in the foods. The objective of the present work is to extract the pigment amaranthus from fresh leaves of Amaranthus hypochondriacus L. cv Don Pedro to characterize it through [...] Read more.
It is known that current quality requirements require the utilization of natural colorants in the foods. The objective of the present work is to extract the pigment amaranthus from fresh leaves of Amaranthus hypochondriacus L. cv Don Pedro to characterize it through spectroscopic techniques, to be used as natural colorants. Full article
Open AccessAbstract Chemical Study of the Essential Oil of Mutisia Friesiana
Molecules 2000, 5(3), 568-570; doi:10.3390/50300568
Published: 22 March 2000
Cited by 2 | PDF Full-text (18 KB)
Abstract The composition of essential oil of Mutisia friesiana (Asteracae) was studied. The oil is a complex system in which 127 compounds were identified. The major components are monoterpenes: b-phellandrene, (Z)-β-ocimene, α and β-pinene and sabinene. Full article
Open AccessAbstract Bioactive Constituents of Conyza Albida
Molecules 2000, 5(3), 571-573; doi:10.3390/50300571
Published: 22 March 2000
Cited by 3 | PDF Full-text (20 KB)
Abstract Alkynes and spathulenol were isolated from Conyza albida (Asteraceae); some of the compounds were lethal against Artemia sp. and cytotoxic against KB cells. Full article
Open AccessAbstract Development and Validation of a Chromatographic Method for the Analysis of Multicompound Pharmaceutical Preparations
Molecules 2000, 5(3), 574-575; doi:10.3390/50300574
Published: 22 March 2000
Cited by 1 | PDF Full-text (16 KB)
Abstract A reverse phase high performance liquid chromatographic assay was carried out for the simultaneous determination of two out of three active principles present in a pharmaceutical preparation. This method was developed to assess the quality of the product. Full article
Open AccessAbstract Study of the Cytotoxic and Antifungal Activities of Neolignans 8.O.4´ and Structurally Related Compounds
Molecules 2000, 5(3), 576-577; doi:10.3390/50300576
Published: 22 March 2000
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Abstract In the present work we report the antifungal and cytotoxic activities of a neolignan 8.O.4´series. The most active antifungal compounds show a significant cytotoxic effect which might be related. Full article
Open AccessAbstract Kinetics of the Aromatic Nucleophilic Substitution Reaction Between 1-Fluoro-2,4-Dinitrobenzene and Perhydroazepine in Ethyl Acetate + Chloroform Solvent Mixtures
Molecules 2000, 5(3), 578-579; doi:10.3390/50300578
Published: 22 March 2000
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Abstract In the present work, the kinetic behavior of the title reaction in ethyl acetate + chloroform solvent mixtures is studied. The experimental results are compared with previous findings. Full article
Open AccessAbstract The Importance of Keto-Enol Forms of Arylpropanoids Acting as Antifungal Compounds
Molecules 2000, 5(3), 580-582; doi:10.3390/50300580
Published: 22 March 2000
Cited by 3 | PDF Full-text (17 KB)
Abstract
We report here the importance of a keto-enol equilibrium of an arylpropanoid series acting as antifungal agents. An interesting relationship between ln MIC, ∆E enolization and net atomic charges was found. Two compounds were synthesized and their MIC evaluated in order to [...] Read more.
We report here the importance of a keto-enol equilibrium of an arylpropanoid series acting as antifungal agents. An interesting relationship between ln MIC, ∆E enolization and net atomic charges was found. Two compounds were synthesized and their MIC evaluated in order to prove the above relationship. Full article
Open AccessAbstract Molecular Interactions Between the Active Sites of RGD (Arg-Gly-Asp) with its Receptor (Integrine)
Molecules 2000, 5(3), 583-584; doi:10.3390/50300583
Published: 22 March 2000
Cited by 1 | PDF Full-text (308 KB)
Abstract A study of the molecular interactions between the active sites of RGD (Arg-Gly-Asp) with it Receptor using simultaions is reported. Our calculations indicate that the guanidine-carboxylate complex is energetically favourd with respect to the guanidine-methyl tetrazole complex. Full article
Open AccessAbstract A Conformational Study of Flexible Cyclic Compounds (Hydrocarbon Rings of 9-12 Members)
Molecules 2000, 5(3), 585-586; doi:10.3390/50300585
Published: 22 March 2000
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Abstract We report here a conformational study of cyclic flexible compounds (rings with 9-12 members). Two methods of systematic search for the minima were used. The results were compared with those obtained using other exploratory methods. Full article
Open AccessAbstract Solvatochromic and Kinetic Response Models in (Ethyl Acetate + Chloroform or Methanol) Solvent Mixtures
Molecules 2000, 5(3), 587-588; doi:10.3390/50300587
Published: 22 March 2000
PDF Full-text (16 KB)
Abstract
The present work analyzes the solvent effects upon the solvatochromic response models for a set of chemical probes and the kinetic response models for an aromatic nucleophilic substitution reaction, in binary mixtures in which both pure components are able to form intersolvent [...] Read more.
The present work analyzes the solvent effects upon the solvatochromic response models for a set of chemical probes and the kinetic response models for an aromatic nucleophilic substitution reaction, in binary mixtures in which both pure components are able to form intersolvent complexes by hydrogen bonding. Full article
Open AccessAbstract Catalytic Hydrogenation Reaction of Naringin-Chalcone. Study of the Electrochemical Reaction
Molecules 2000, 5(3), 589-590; doi:10.3390/50300589
Published: 22 March 2000
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Abstract The electrocatalytic hydrogenation reaction of naringin derivated chalcone is studied. The reaction is carried out with different catalysts in order to compare with the classic catalytic hydrogenation. Full article
Open AccessAbstract Fluorescence Resonance Energy Transfer Using Spiropyran and Diarylethene Photochromic Acceptors
Molecules 2000, 5(3), 591-593; doi:10.3390/50300591
Published: 22 March 2000
Cited by 6 | PDF Full-text (28 KB)
Abstract
We describe the preparation and photophysical characterization of two model compounds designed to test a new approach for the quantitative determination of Fluorescence Resonance Energy Transfer (FRET) in biological systems. The method enables modulation of FRET by exploiting the unique reversible spectral [...] Read more.
We describe the preparation and photophysical characterization of two model compounds designed to test a new approach for the quantitative determination of Fluorescence Resonance Energy Transfer (FRET) in biological systems. The method enables modulation of FRET by exploiting the unique reversible spectral properties of photochromic diarylethenes and spiropyrans to create switchable energy acceptors. Full article
Open AccessAbstract Stereoselective Synthesis of 8-Trialkylstannylmenthols
Molecules 2000, 5(3), 594-595; doi:10.3390/50300594
Published: 22 March 2000
PDF Full-text (19 KB)
Abstract
Trialkyltin menthones of type 2 are obtained selectively by 1,4-addition of trialkylstannyl lithium to (-)-pulegone. Reduction of 2 with borane in THF using as catalyst the reagent prepared from borane and (S)-valinol gave a mixture of the corresponding trialkyltin alcohols 3 (Me: [...] Read more.
Trialkyltin menthones of type 2 are obtained selectively by 1,4-addition of trialkylstannyl lithium to (-)-pulegone. Reduction of 2 with borane in THF using as catalyst the reagent prepared from borane and (S)-valinol gave a mixture of the corresponding trialkyltin alcohols 3 (Me: 84%; n-Bu: 90,6%) and 4 (Me: 16% and n-Bu: 9,4%). Full article
Open AccessAbstract Polymerization Mechanism of α,α’-bis(Tetrahydrothiophenio)-β-xylene Dichloride
Molecules 2000, 5(3), 596-597; doi:10.3390/50300596
Published: 22 March 2000
PDF Full-text (20 KB)
Abstract
A experimental study was performed regarding the influence of the base nature and solvent on the reactive intermediate concentration in the base-promoted bissulfonium salts polymerization. Such polymerization reaction is part of a synthetic procedure used to prepare conjugated polymers. In addition, a [...] Read more.
A experimental study was performed regarding the influence of the base nature and solvent on the reactive intermediate concentration in the base-promoted bissulfonium salts polymerization. Such polymerization reaction is part of a synthetic procedure used to prepare conjugated polymers. In addition, a theoretical study suggest that a one-electron transfer could be involved in the initiation step. Full article
Open AccessAbstract Enantioselective Addition of Grignard Reagents to Aldehydes
Molecules 2000, 5(3), 598-599; doi:10.3390/50300598
Published: 22 March 2000
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Abstract The addition of Grignard reagents to aldehydes in the presence of chiral aminoalcohols shows a moderate enantioselectivity. The study carried out with a series of ligands allows the correlation between the structural characteristics and their reactivity. Full article
Open AccessAbstract O-Sulfated Derivatives of Glucuronic Acid
Molecules 2000, 5(3), 600-601; doi:10.3390/50300600
Published: 22 March 2000
PDF Full-text (16 KB)
Abstract 4-O-Substituted D-glucuronic acid derivatives were synthesized from D-glucose in order to study the regioselectivity of sulfation. Full article
Open AccessAbstract Synthesis and Computational Simulation of New Phosphorilated Sulfoximines with Insecticidal Activity
Molecules 2000, 5(3), 602-604; doi:10.3390/50300602
Published: 22 March 2000
PDF Full-text (32 KB)
Abstract
New organophosphorus insecticides of dialkylsulphoximines derived with activity upon acetylcholinesterase were synthesized. The obtained compounds were characterized by NMR and IR, and anticholinesterase activity and toxicity was measured. A simulation through computer was done in order to establish the relationship between structure [...] Read more.
New organophosphorus insecticides of dialkylsulphoximines derived with activity upon acetylcholinesterase were synthesized. The obtained compounds were characterized by NMR and IR, and anticholinesterase activity and toxicity was measured. A simulation through computer was done in order to establish the relationship between structure and activity. Full article
Open AccessAbstract Phytochemical Study Conyza Sophiaefolia. Antiinflammatory Activity
Molecules 2000, 5(3), 605-607; doi:10.3390/50300605
Published: 22 March 2000
Cited by 1 | PDF Full-text (18 KB)
Abstract
From the aerial parts of Conyza sophiaefolia a new alicyclic furan diterpene was isolated and characterized as an E-isomer in C6 of centipedic acid. In addition, the new clerodane type diterpene 12-epi-bacchotricuneatin A as well as two known related diterpenoids were [...] Read more.
From the aerial parts of Conyza sophiaefolia a new alicyclic furan diterpene was isolated and characterized as an E-isomer in C6 of centipedic acid. In addition, the new clerodane type diterpene 12-epi-bacchotricuneatin A as well as two known related diterpenoids were identified. The flavone apigenine was also isolated. Structures were determined on the basis of spectroscopic evidence. Full article
Open AccessAbstract Structure-Properties Relationship of Dimeric Surfactants from Butyl Glucosides
Molecules 2000, 5(3), 608-609; doi:10.3390/50300608
Published: 22 March 2000
Cited by 2 | PDF Full-text (28 KB)
Abstract Carbohydrate containing dimeric surfactants were synthesized starting from Dglucose. Three different spacers were used to link the sugar moieties. The critical micelle concentration (CMC) for these new compounds was determined. Full article
Open AccessAbstract Synthesis of 2,3-Butanedione over TS-1, Ti-NCl, TiMCM-41, Ti-Beta, Fe-Si, Fe-Beta and VS-1 Zeolites
Molecules 2000, 5(3), 610-611; doi:10.3390/50300610
Published: 22 March 2000
Cited by 1 | PDF Full-text (17 KB)
Abstract
The purpose of this work is the synthesis of 2,3-butanedione (diacetyl) by selective oxidation of 2-butanone (methyl ethyl ketone) in the presence of O2 and H2O2 30% as oxidants. All the tests were performed over several selective oxidation [...] Read more.
The purpose of this work is the synthesis of 2,3-butanedione (diacetyl) by selective oxidation of 2-butanone (methyl ethyl ketone) in the presence of O2 and H2O2 30% as oxidants. All the tests were performed over several selective oxidation zeolite catalysts, synthesized and characterized in our laboratory. Full article
Open AccessAbstract Reaction Mechanism for the Cyclization of 3-[γ,γ-Dimethylallyl]Coumaric Acid Methyl Ester in Dimethyl Sulfoxide (DMSO)
Molecules 2000, 5(3), 612-613; doi:10.3390/50300612
Published: 22 March 2000
PDF Full-text (16 KB)
Open AccessAbstract Grindelic Acid Production in Grindelia Pulchella Cell Suspension Cultures Elicited with CuSO4
Molecules 2000, 5(3), 614-615; doi:10.3390/50300614
Published: 22 March 2000
Cited by 1 | PDF Full-text (18 KB)
Open AccessAbstract Influence of Some Thia- or Azasubstituted Butyric Acid Derivatives on the Chemical Shift of the Benzene Ring Carbon Atoms
Molecules 2000, 5(3), 616-619; doi:10.3390/50300616
Received: 26 January 2000 / Accepted: 17 March 2000 / Published: 22 March 2000
PDF Full-text (15 KB)
Abstract Eight thia- or azasubstituted butyric acid derivatives were prepared and the influence of these substituents on the chemical shifts of the benzene ring carbon atoms was studied. Full article

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