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Molecules, Volume 9, Issue 8 (August 2004), Pages 622-712

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Research

Open AccessArticle A Facile Synthesis of Substituted Benzyl Selenocyanates†
Molecules 2004, 9(8), 622-626; doi:10.3390/90800622
Received: 8 May 2004 / Accepted: 8 May 2004 / Published: 31 July 2004
Cited by 7 | PDF Full-text (135 KB) | HTML Full-text | XML Full-text
Abstract Benzyl selenocyanates can be made from the corresponding benzylic bromides or chlorides in 30-60 minutes using acetonitrile as a solvent. The products may be obtained pure in satisfactory yields without recourse to chromatography. Full article
Open AccessArticle Convenient Replacement of the Hydroxy by an Amino Group in 4 Hydroxycoumarin and 4-Hydroxy-6-methyl-2-pyrone under Microwave Irradiation
Molecules 2004, 9(8), 627-631; doi:10.3390/90800627
Received: 4 June 2004 / Accepted: 18 June 2004 / Published: 31 July 2004
Cited by 13 | PDF Full-text (158 KB) | HTML Full-text | XML Full-text
Abstract
The reaction of 4-hydroxycoumarin (1) with some primary amines 2a-h and morpholine (2i) under microwave irradiation occurred without opening of the lactone ring to give N-substituted 4-aminocoumarins 3a-i in excellent yields. Under the same experimental conditions, 4-hydroxy-6-methyl-2-pyrone (4) reacted with benzylamine (2e) or
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The reaction of 4-hydroxycoumarin (1) with some primary amines 2a-h and morpholine (2i) under microwave irradiation occurred without opening of the lactone ring to give N-substituted 4-aminocoumarins 3a-i in excellent yields. Under the same experimental conditions, 4-hydroxy-6-methyl-2-pyrone (4) reacted with benzylamine (2e) or 2-phenyl- ethylamine (2f) to give the corresponding N,N'-disubstituted 4-amino-6-methyl-2-pyridones 5e,f. The main advantages of this procedure are dramatically shortened reaction times, higher amine utilization and considerably improved yields. Full article
Open AccessArticle A Comparative Study of O2, CO and CN Binding to Heme IX Protein Models
Molecules 2004, 9(8), 632-649; doi:10.3390/90800632
Received: 26 April 2004 / Accepted: 7 June 2004 / Published: 31 July 2004
Cited by 3 | PDF Full-text (287 KB) | HTML Full-text | XML Full-text
Abstract
Parametrization of a molecular-mechanics program to include terms specificfor five- and six-coordinate transition metal complexes results in computer-simulatedstructures of heme complexes. The principal new feature peculiar to five and sixcoordination is a term that measures the effect of electron-pair repulsion modified by theligand
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Parametrization of a molecular-mechanics program to include terms specificfor five- and six-coordinate transition metal complexes results in computer-simulatedstructures of heme complexes. The principal new feature peculiar to five and sixcoordination is a term that measures the effect of electron-pair repulsion modified by theligand electronegativity and takes into account the different structural possibilities. Themodel system takes into account the structural differences of the fixing centre in thehaemoglobin subunits. The customary proximal histidine is added. The prosthetic groupheme IX is wholly considered in our model. The calculations show clearly that certainconformations are much more favourable that others for fixing O2. From the O2 bindingin haemoglobin, myoglobin and simple Fe porphyrin models it is concluded that the bentO2 ligand is best viewed as bound superoxide O2. Axial ligands are practically free-rotating. A small modification of the model in both crystal and protein matrix affects theorientation of the ligands in experimental systems. Full article
Open AccessArticle Isolation and X-ray Crystal Structure of Tetrahydroisoquinoline Alkaloids from Calycotome Villosa Subsp. intermedias
Molecules 2004, 9(8), 650-657; doi:10.3390/90800650
Received: 18 December 2003 / Revised: 6 July 2004 / Accepted: 11 July 2004 / Published: 31 July 2004
Cited by 5 | PDF Full-text (192 KB) | HTML Full-text | XML Full-text
Abstract Two tetrahydroisoquinoline alkaloids were extracted from the alkaloid fraction of a methanol extract of the seeds of Calycotome Villosa Subsp. intermedia. Their structures were established as (R)-1-hydroxymethyl-7-8-dimethoxy-1,2,3,4-tetrahydro- isoquinoline (1) and (S)-7-hydroxymethyl-2-3-dimethoxy-7,8,9,10-tetrahydroisoquinoline chloride (2) by spectroscopic techniques and X-ray diffraction analysis. Full article
Open AccessArticle Synthesis of Substituted Stilbenes via the Knoevenagel Condensation
Molecules 2004, 9(8), 658-665; doi:10.3390/90800658
Received: 15 January 2004 / Revised: 4 July 2004 / Accepted: 8 July 2004 / Published: 31 July 2004
Cited by 13 | PDF Full-text (174 KB) | HTML Full-text | XML Full-text
Abstract
Knoevenagel condensations between aldehydes and substrates containing active methylene groups were carried out in ethanol at room temperature, in the presence of potassium phosphate, to afford unsymmetrical olefins. These condensations have been shown to afford only the E-isomers in greater than 80% yields.
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Knoevenagel condensations between aldehydes and substrates containing active methylene groups were carried out in ethanol at room temperature, in the presence of potassium phosphate, to afford unsymmetrical olefins. These condensations have been shown to afford only the E-isomers in greater than 80% yields. Salicylaldehyde first produces the Knoevenagel condensation products, which undergo a subsequent heterocyclization to give coumarin derivatives. The structures of the synthesized compounds were established on the basis of UV, IR, MS and NMR spectroscopy. Full article
Open AccessArticle Leishmanicidal Activity of Passifloricin A and Derivatives
Molecules 2004, 9(8), 666-672; doi:10.3390/90800666
Received: 19 April 2004 / Revised: 28 June 2004 / Accepted: 6 July 2004 / Published: 31 July 2004
Cited by 8 | PDF Full-text (155 KB) | HTML Full-text | XML Full-text
Abstract Several natural and hemisyntetic passifloricins were assayed against Leishmania panamensis amastigotes. High leishmanicidal activity as well as toxicity was observed. The structure of a new compound is also reported. Full article
Open AccessArticle High Throughput Screening and QSAR-3D/CoMFA: Useful Tools to Design Predictive Models of Substrate Specificity for Biocatalysts†
Molecules 2004, 9(8), 673-693; doi:10.3390/90800673
Received: 17 March 2004 / Accepted: 10 July 2004 / Published: 31 July 2004
Cited by 10 | PDF Full-text (403 KB) | HTML Full-text | XML Full-text
Abstract
After a hierarchical microbial screening process, new microorganisms have been discovered that act as biocatalysts for the stereoselective oxidation of secondary alcohols or for ketone reduction. Oxidation activity is more widespread in yeasts and bacteria, while actinomycetes, filamentous fungi and yeasts present the
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After a hierarchical microbial screening process, new microorganisms have been discovered that act as biocatalysts for the stereoselective oxidation of secondary alcohols or for ketone reduction. Oxidation activity is more widespread in yeasts and bacteria, while actinomycetes, filamentous fungi and yeasts present the highest reduction activities. QSAR-3D/CoMFA is an adequate technique to design predictive models of the biocatalysts’ activity. In this paper CoMFA models are designed to compare the activities of the biocatalysts selected for the oxidation of alcohols and for the reduction of ketones, starting from the results obtained during the screening process. These models are useful for learning about the activity of these microorganisms and to compare the substrate specificity requirements between alcohol oxidation and ketone reduction biocatalysts. Full article
Open AccessArticle Synthesis of Some Novel 11b-Substituted Pyrimido[6,1-a]-isoquinoline Derivatives
Molecules 2004, 9(8), 694-704; doi:10.3390/90800694
Received: 17 June 2004 / Accepted: 29 June 2004 / Published: 31 July 2004
Cited by 3 | PDF Full-text (225 KB) | HTML Full-text | XML Full-text
Abstract A series of novel 11b-substituted 1,6,7,11b-tetrahydropyrimido[6,1-a]- isoquinoline-2,4-diones and 4-thioxo-1,3,4,6,7,11b-hexahydropyrimido[6,1-a]isoquinolin-2- ones were synthesized, utilizing two alternative strategies for ring closure of tetrahydroisoquinoline intermediates obtained from N-phenethyl enaminones Full article
Open AccessArticle Synthesis of Benzoxazinone Derivatives: A New Route to 2 (N Phthaloylmethyl)-4H-3,1-benzoxazin-4-one
Molecules 2004, 9(8), 705-712; doi:10.3390/90800705
Received: 8 May 2004 / Revised: 29 July 2004 / Accepted: 30 July 2004 / Published: 31 July 2004
Cited by 11 | PDF Full-text (157 KB) | HTML Full-text | XML Full-text
Abstract
A new method has been designed to prepare the known benzoxazinone derivative 2-(N-phthaloylmethyl)-4H-3,1-benzoxazin-4-one (4). The acyl chloride derivative N-phthaloylglycine reacts with anthranilic acid in chloroform, in the presence of triethylamine, to give an intermediate that is then reacted with cyanuric chloride, used as
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A new method has been designed to prepare the known benzoxazinone derivative 2-(N-phthaloylmethyl)-4H-3,1-benzoxazin-4-one (4). The acyl chloride derivative N-phthaloylglycine reacts with anthranilic acid in chloroform, in the presence of triethylamine, to give an intermediate that is then reacted with cyanuric chloride, used as a cyclization agent, to produce the benzoxazinone derivative. Full article

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