Molecules

159 KiB

Open AccessArticle

Synthetic Studies on Erythromycin Derivatives: Reactivity of the C12-21 Alkene

by Wei-Min Chen

Molecules 2006, 11(1), 121-129; https://doi.org/10.3390/11010121 - 31 Jan 2006

Cited by 4 | Viewed by 9585

The reactivity of the C12-21 alkene of some erythromycin A derivatives was studied. This double bond was easily oxidized to the corresponding epoxide with excellent stereoselectivity. A single crystal X-ray structure showed that the epoxide moiety was on the same side as the [...] Read more.

The reactivity of the C12-21 alkene of some erythromycin A derivatives was studied. This double bond was easily oxidized to the corresponding epoxide with excellent stereoselectivity. A single crystal X-ray structure showed that the epoxide moiety was on the same side as the acetonide. When an erythromycin derivative containing a C12-21 alkene was treated with diazomethane a [3+2] cycloaddition affording a pyrazoline occurred. In the case of 6-O-allylated erythromycin derivatives the C12-21 alkene was selectively epoxidized in the presence of the 6-O-allyl moiety. These results show that the C12-21 alkene is an active reaction site, which can be used for useful further modification of erythromycin derivatives. Full article

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194 KiB

Open AccessArticle

Polymer – Supported Cobalt (II) Catalysts for the Oxidation of Alkenes

by Edyta Błaż and Jan Pielichowski

Molecules 2006, 11(1), 115-120; https://doi.org/10.3390/11010115 - 31 Jan 2006

Cited by 39 | Viewed by 8185

Abstract

Polymer-supported heterogeneous catalysts in a form of complexes of 8-hydroxy- quinoline with cobalt acetate were synthesized. Conjugated polymers – polyaniline (PANI), poly-o-toluidine (POT), poly-o-anisidine (POA) – were used as supports. Oxidation reactions of aliphatic and aromatic hydrocarbons were carried out in the presence [...] Read more.

Polymer-supported heterogeneous catalysts in a form of complexes of 8-hydroxy- quinoline with cobalt acetate were synthesized. Conjugated polymers – polyaniline (PANI), poly-o-toluidine (POT), poly-o-anisidine (POA) – were used as supports. Oxidation reactions of aliphatic and aromatic hydrocarbons were carried out in the presence of molecular oxygen at atmospheric pressure and epoxides or ketones were obtained as the main products with high selectivity. Full article

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174 KiB

Open AccessArticle

Screening Analyses of Pinosylvin Stilbenes, Resin Acids and Lignans in Norwegian Conifers

by Hanne Hovelstad, Ingebjorg Leirset, Karin Oyaas and Anne Fiksdahl

Molecules 2006, 11(1), 103-114; https://doi.org/10.3390/11010103 - 31 Jan 2006

Cited by 75 | Viewed by 13689

Abstract

The content and distribution of stilbenes and resin acids in Scots pine (Pinus sylvestris) and spruce (Picea abies), sampled in central Norway, have been examined. The contents of pinosylvin stilbenes in pine heartwood/living knots were 0.2-2/2-8 % (w/w). No stilbenes could be detected [...] Read more.

The content and distribution of stilbenes and resin acids in Scots pine (Pinus sylvestris) and spruce (Picea abies), sampled in central Norway, have been examined. The contents of pinosylvin stilbenes in pine heartwood/living knots were 0.2-2/2-8 % (w/w). No stilbenes could be detected in spruce (Picea abies). The resin acid contents of pine sapwood/heartwood and knots were 1-4 and 5-10 % (w/w), respectively. Minor amounts of resin acids (< 0.2/< 0.04 %w/w) were identified in spruce wood/knots. The lignan content in knots of Norwegian spruce was 6.5 % (w/w). Diastereomerically pure hydroxymatairesinol (HMR, 84 % of total lignans) was readily isolated from this source since only minor quantities (2.6 % of total lignans) of the allo-HMR diastereomer was detected. Insignificant amounts of lignans were present in the sapwood. Lignans could not be detected in the sapwood or knots of Norwegian sallow (Salix caprea), birch (Betula pendula) or juniper (Juniperus communis). Full article

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158 KiB

Open AccessArticle

Synthesis of 2,4,6-Tri-substituted-1,3,5-Triazines

by Carlos A. M. Afonso, Nuno M. T. Lourenco and Andreia De A. Rosatella

Molecules 2006, 11(1), 81-102; https://doi.org/10.3390/11010081 - 31 Jan 2006

Cited by 82 | Viewed by 18171

Abstract

Several specific synthetic protocols were developed for the preparation from cyanuric chloride of a range of symmetric and non-symmetric di- and tri-substituted 1,3,5-triazines containing alkyl, aromatic, hindered, chiral and achiral hydroxyalkyl, ester and imidazole groups via sequential nucleophilic substitution of the C-Cl bond [...] Read more.

Several specific synthetic protocols were developed for the preparation from cyanuric chloride of a range of symmetric and non-symmetric di- and tri-substituted 1,3,5-triazines containing alkyl, aromatic, hindered, chiral and achiral hydroxyalkyl, ester and imidazole groups via sequential nucleophilic substitution of the C-Cl bond by C-O, C-N and C-S bonds. Full article

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85 KiB

Open AccessArticle

Reactions of 9-Alkyl-3-aminocarbazoles with Ethyl-3-oxo-butanoate and Identification of the Products Obtained

by Birute Sapijanskaite, Ytautas Mickevicius and Gema Mikulskiene

Molecules 2006, 11(1), 72-80; https://doi.org/10.3390/11010072 - 31 Jan 2006

Cited by 2 | Viewed by 7028

Abstract

The reactions in benzene of 9-alkyl-3-aminocarbazoles with ethyl-3-oxobutanoateyielded ethyl-3-[(9-alkyl-9H-carbazol-3-yl)amino]but-2-enoate condensation products or N-(9-ethyl-9H-carbazol-3-yl)-3-oxobutanamide acylation products. The condensation productswere cyclized to the corresponding 4,7-dihydro-pyrido[2,3-c]-carbazol-1-ones upon heatingin mineral oil at 240-250 °C. The structures of the synthesized compounds were investigatedby IR, mass spectrometry, ¹H- [...] Read more.

The reactions in benzene of 9-alkyl-3-aminocarbazoles with ethyl-3-oxobutanoateyielded ethyl-3-[(9-alkyl-9H-carbazol-3-yl)amino]but-2-enoate condensation products or N-(9-ethyl-9H-carbazol-3-yl)-3-oxobutanamide acylation products. The condensation productswere cyclized to the corresponding 4,7-dihydro-pyrido[2,3-c]-carbazol-1-ones upon heatingin mineral oil at 240-250 °C. The structures of the synthesized compounds were investigatedby IR, mass spectrometry, ¹H- and ¹³C-NMR spectroscopy and MM2 molecular mechanicsand AM1 semi-empirical quantum mechanical methods. Full article

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135 KiB

Open AccessArticle

An Efficient Scalable Synthesis of 2,3-Epoxypropyl Phenylhydrazones

by Vytautas Getautis, Maryte Daskeviciene, Tadas Malinauskas, Albina Stanisauskaite and Jolanta Stumbraite

Molecules 2006, 11(1), 64-71; https://doi.org/10.3390/11010064 - 31 Jan 2006

Cited by 10 | Viewed by 7221

Abstract

A series of mono and di-N-2,3-epoxypropyl N-phenylhydrazones have beenprepared on a large scale by reaction of the corresponding N-phenylhydrazones of9-ethyl-3-carbazolecarbaldehyde, 9-ethyl-3,6-carbazoledicarbaldehyde, 4-dimethyl-amino-, 4-diethylamino-, 4-benzylethylamino-, 4-(diphenylamino)-, 4-(4,4-4'-dimethyl-diphenylamino)-, 4-(4-formyldiphenylamino)- and 4-(4-formyl-4'-methyldiphenyl-amino)benzaldehyde with epichlorohydrin in the presence of KOH and anhydrousNa₂SO₄. Full article

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106 KiB

Open AccessArticle

Synthesis of Some New bis-Schiff Bases of Isatin and 5-Fluoroisatin in a Water Suspension Medium

by A. A. Jarrahpour and D. Khalili

Molecules 2006, 11(1), 59-63; https://doi.org/10.3390/11010059 - 31 Jan 2006

Cited by 23 | Viewed by 7698

Abstract

Condensation of aromatic primary bis-amines with isatin (1H-indole-2,3-dione) and 5-flouroisatin occurred cleanly and efficiently in a water suspension mediumwithout using any organic solvent or acid catalyst. The corresponding bis-Schiff baseswere obtained in good yields and were easily isolated by filtration. Their structures wereconfirmed [...] Read more.

Condensation of aromatic primary bis-amines with isatin (1H-indole-2,3-dione) and 5-flouroisatin occurred cleanly and efficiently in a water suspension mediumwithout using any organic solvent or acid catalyst. The corresponding bis-Schiff baseswere obtained in good yields and were easily isolated by filtration. Their structures wereconfirmed by ¹H-NMR, ¹³C-NMR, IR and mass spectra. Full article

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225 KiB

Open AccessArticle

Synthesis of Novel N-Sulfonyl Monocyclic β-Lactams as Potential Antibacterial Agents

by Aliasghar Jarrahpour and Maaroof Zarei

Molecules 2006, 11(1), 49-58; https://doi.org/10.3390/11010049 - 31 Jan 2006

Cited by 64 | Viewed by 8705

Abstract

New cis monocyclic β-lactams were synthesized by [2+2] Staudinger cycloaddition reactions of the imine (3,4-dimethoxybenzylidene)-(4-methoxyphenyl)- amine and ketenes derived from different acyl chlorides and Et3N. These monocyclic β-lactams were then cleaved by ceric ammonium nitrate (CAN) to give NH-monocyclic β-lactams, which in turn [...] Read more.

New cis monocyclic β-lactams were synthesized by [2+2] Staudinger cycloaddition reactions of the imine (3,4-dimethoxybenzylidene)-(4-methoxyphenyl)- amine and ketenes derived from different acyl chlorides and Et3N. These monocyclic β-lactams were then cleaved by ceric ammonium nitrate (CAN) to give NH-monocyclic β-lactams, which in turn were converted to N-sulfonyl monocyclic β-lactams by treatment with four different sulfonyl chlorides in the presence of Et3N and 4,4-dimethyl- aminopyridine (DMAP). Full article

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53 KiB

Open AccessArticle

Synthesis of Some New 2-(3-Aryl-1-phenyl-4-pyrazolyl)-benzoxazoles Using Hypervalent Iodine Mediated Oxidative Cyclization of Schiff’s Bases

by Om Prakash, Kamaljeet Pannu and Ajay Kumar

Molecules 2006, 11(1), 43-48; https://doi.org/10.3390/11010043 - 31 Jan 2006

Cited by 49 | Viewed by 8668

Abstract

Ten new 2-(3-aryl-1-phenyl-4-pyrazolyl)benzoxazoles have been synthesized by oxidative intramolecular cyclization of the corresponding Schiff’s bases using iodobenzene diacetate in methanol as an oxidant. Full article

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171 KiB

Open AccessArticle

Criss-cross Cycloadditions on Ketazines Derived from Alicyclic Ketones

by Jiri Verner and Milan Potacek

Molecules 2006, 11(1), 34-42; https://doi.org/10.3390/11010034 - 31 Jan 2006

Cited by 21 | Viewed by 9338

Abstract

The reactivity of alicyclic ketazines in criss-cross cycloadditions was investigated. They react with potassium cyanate and ammonium thiocyanate in the presence of acetic acid to form spirocyclic perhydro[1,2,4]triazolo[1,2-a][1,2,4]triazole-1,5-diones and perhydro[1,2,4]triazolo[1,2-a][1,2,4]triazole-1,5-dithiones, respectively, in relatively high yields. Full article

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367 KiB

Open AccessReview

Reactivity and Biological Activity of the Marine Sesquiterpene Hydroquinone Avarol and Related Compounds from Sponges of the Order Dictyoceratida

by Dusan Sladic and Miroslav J. Gasic

Molecules 2006, 11(1), 1-33; https://doi.org/10.3390/11010001 - 31 Jan 2006

Cited by 62 | Viewed by 13066

Abstract

A review of results of bioactivity and reactivity examinations of marine sesquiterpene (hydro)quinones is presented. The article is focused mostly on friedo- rearranged drimane structural types, isolated from sponges of the order Dictyoceratida. Examples of structural correlations are outlined. Available results on the [...] Read more.

A review of results of bioactivity and reactivity examinations of marine sesquiterpene (hydro)quinones is presented. The article is focused mostly on friedo- rearranged drimane structural types, isolated from sponges of the order Dictyoceratida. Examples of structural correlations are outlined. Available results on the mechanism of redox processes and examinations of chemo- and regioselectivity in addition reactions are presented and, where possible, analyzed in relation to established bioactivities. Most of the bioactivity examinations are concerned with antitumor activities and the mechanism thereof, such as DNA damage, arylation of nucleophiles, tubulin assembly inhibition, protein kinase inhibition, inhibition of the arachidonic cascade, etc. Perspectives on marine drug development are discussed with respect to biotechnological methods and synthesis. Examples of the recognition of validated core structures and synthesis of structurally simplified compounds retaining modes of activity are analyzed. Full article

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Molecules, Volume 11, Issue 1 (January 2006) – 11 articles , Pages 1-129

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