Molecules

157 KiB

Open AccessArticle

Synthesis of Benzoxazinone Derivatives: A New Route to 2 (N Phthaloylmethyl)-4H-3,1-benzoxazin-4-one

by Mehdi Shariat and Sohrab Abdollahi

Molecules 2004, 9(8), 705-712; https://doi.org/10.3390/90800705 - 31 Jul 2004

Cited by 33 | Viewed by 11531

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 [...] Read more.

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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225 KiB

Open AccessArticle

Synthesis of Some Novel 11b-Substituted Pyrimido[6,1-a]-isoquinoline Derivatives

by Plamen A. Angelov, Iliyan I. Ivanov and Atanas P. Venkov

Molecules 2004, 9(8), 694-704; https://doi.org/10.3390/90800694 - 31 Jul 2004

Cited by 5 | Viewed by 6398

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

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403 KiB

Open AccessArticle

High Throughput Screening and QSAR-3D/CoMFA: Useful Tools to Design Predictive Models of Substrate Specificity for Biocatalysts†

by J. D. Carballeira, M. A. Quezada, E. Álvarez and J. V. Sinisterra

Molecules 2004, 9(8), 673-693; https://doi.org/10.3390/90800673 - 31 Jul 2004

Cited by 12 | Viewed by 8507

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 [...] Read more.

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

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155 KiB

Open AccessArticle

Leishmanicidal Activity of Passifloricin A and Derivatives

by Wilson Cardona G., Winston Quiñones Quiñones F. and Fernando Echeverri L.

Molecules 2004, 9(8), 666-672; https://doi.org/10.3390/90800666 - 31 Jul 2004

Cited by 17 | Viewed by 7047

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

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174 KiB

Open AccessArticle

Synthesis of Substituted Stilbenes via the Knoevenagel Condensation

by Shar Saad Al-Shihry

Molecules 2004, 9(8), 658-665; https://doi.org/10.3390/90800658 - 31 Jul 2004

Cited by 24 | Viewed by 10101

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. [...] Read more.

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

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192 KiB

Open AccessArticle

Isolation and X-ray Crystal Structure of Tetrahydroisoquinoline Alkaloids from Calycotome Villosa Subsp. intermedias

by Ali El Antri, Ibtissam Messouri, Mohamed Bouktaib, Rachid El Alami, Michael Bolte, Brahim El Bali and Mohammed Lachkar

Molecules 2004, 9(8), 650-657; https://doi.org/10.3390/90800650 - 31 Jul 2004

Cited by 9 | Viewed by 10734

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

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287 KiB

Open AccessArticle

A Comparative Study of O2, CO and CN Binding to Heme IX Protein Models

by Francisco Torrens

Molecules 2004, 9(8), 632-649; https://doi.org/10.3390/90800632 - 31 Jul 2004

Cited by 8 | Viewed by 9849

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 [...] Read more.

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

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158 KiB

Open AccessArticle

Convenient Replacement of the Hydroxy by an Amino Group in 4 Hydroxycoumarin and 4-Hydroxy-6-methyl-2-pyrone under Microwave Irradiation

by Edmont V. Stoyanov and Ivo C. Ivanov

Molecules 2004, 9(8), 627-631; https://doi.org/10.3390/90800627 - 31 Jul 2004

Cited by 24 | Viewed by 9486

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 [...] Read more.

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

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135 KiB

Open AccessArticle

A Facile Synthesis of Substituted Benzyl Selenocyanates†

by Linda A. Jacob, Bianca Matos, Corey Mostafa, Joelle Rodriguez and Joanne Kivella Tillotson

Molecules 2004, 9(8), 622-626; https://doi.org/10.3390/90800622 - 31 Jul 2004

Cited by 20 | Viewed by 8369

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

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

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