Molecules

146 KiB

Open AccessArticle

Fused Heterocycles: Synthesis of Some New Imidazo[1,2-a]- pyridine Derivatives

by Birgul Ozden Kasimogullari and Zafer Cesur

Molecules 2004, 9(10), 894-901; https://doi.org/10.3390/91000894 - 30 Sep 2004

Cited by 24 | Viewed by 8321

Some new thiazolidines and spirothiazolidines derived from hydrazones of2-methylimidazo[1,2-a]pyridine-3-carboxylic acid hydrazide, a bioisosteric derivative ofisoniazid, were synthesized and characterized by analytical, IR, ¹H- and ¹³C-NMR andmass spectral data. Some of the newly synthesized compounds were screened for theirantimycobacterial activities. None of [...] Read more.

Some new thiazolidines and spirothiazolidines derived from hydrazones of2-methylimidazo[1,2-a]pyridine-3-carboxylic acid hydrazide, a bioisosteric derivative ofisoniazid, were synthesized and characterized by analytical, IR, ¹H- and ¹³C-NMR andmass spectral data. Some of the newly synthesized compounds were screened for theirantimycobacterial activities. None of the tested compounds showed significant in vitroantituberculous activity at 6.25 μg/mL (MIC rifampin 0.031 μg/mL). Full article

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202 KiB

Open AccessArticle

Theoretical Study of Some Nitrososulfamide Compounds with Antitumor Activity

by Khatmi Djameleddine, Seridi Soumeya and Madi Fatiha

Molecules 2004, 9(10), 883-893; https://doi.org/10.3390/91000883 - 30 Sep 2004

Cited by 3 | Viewed by 8058

Abstract

The lowest-energy conformations of four 2-chloroethylnitrososulfamides were determined using the MM+ molecular mechanics method as implemented in Hyperchem 6.0. Some of the calculated structural parameters, angles and bonds lengths were compared with the crystal structure data of N-nitroso-N-(2-chloroethyl)-N’-sulfamoyl- proline. Using MM+, AM1 and [...] Read more.

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

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399 KiB

Open AccessArticle

Crystal Structure and Characterization of the Dinuclear Cd(II) Complex [Cd(H₂O)₂(ο-HOC₆H₄COO)₂]₂

by Fangfang Jian, Hailian Xiao, Pingping Sun and Pusu Zhao

Molecules 2004, 9(10), 876-882; https://doi.org/10.3390/91000876 - 30 Sep 2004

Cited by 14 | Viewed by 8516

Abstract

The structure of a new binuclear cadmium (II) complex, [Cd(H₂O)₂(Sal)₂]₂ (Sal= salicylate), has been determined by X-ray crystallography. It was also characterized byelemental analysis, its IR spectrum and thermogravimetric-differential scanningcalorimetry (TG-DSC). It crystallizes in the monoclinic [...] Read more.

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

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190 KiB

Open AccessArticle

Reactivity of 2-Thiohydantoins Towards Various Electrophilic Reagents: Applications to the Synthesis of New 2-Ylidene-3,5-dihydro-4H-imidazol-4-ones.

by Jean-René Chérouvrier, François Carreaux and Jean Pierre Bazureau

Molecules 2004, 9(10), 867-875; https://doi.org/10.3390/91000867 - 30 Sep 2004

Cited by 36 | Viewed by 7779

Abstract

A new route to 5-(imidazolidin-2-ylidene)-2-methylsulfanyl-3,5-dihydro-imidazol-4-ones 4a-c using ketene dithioacetal intermediates 3a-c is described. Thereactivity of thiohydantoin derivatives 2a-c towards N,N-dimethylformamide diethylacetal(DMF-DEA) was also explored using solvent-free technique under microwave irradiation(μω). The ¹H- and ¹³C-NMR spectra of some representative products are discussed. Full article

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185 KiB

Open AccessArticle

Synthesis and Spectroscopic Characterization of New Schiff Bases Containing the Benzo-15-Crown-5 Moiety

by Zeliha Hayvalı, Mustafa Hayvalı and Hakan Dal

Molecules 2004, 9(10), 860-866; https://doi.org/10.3390/91000860 - 30 Sep 2004

Cited by 12 | Viewed by 6909

Abstract

New crown ether Schiff base derivatives were prepared by the condensation of4’-formylbenzo-15-crown-5 or 4’-formyl-5’-hydroxybenzo-15-crown-5 with 1,2-bis(2-aminophenoxy)ethane. The structures of these new compounds were confirmed on thebasis of elemental analysis, IR, ¹H- and ¹³C-NMR, UV-Vis and mass spectroscopic data. Full article

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200 KiB

Open AccessArticle

Unexpected Hydrazinolysis Behaviour of 1-Chloro-4-methyl-5H-pyridazino[4,5-b]indole and a Convenient Synthesis of New [1,2,4]-Triazolo[4’,3’:1,6]pyridazino[4,5-b]indoles

by Hussein El-Kashef, Abdelrahman A. H. Farghaly, Norbert Haider and Andrea Wobus

Molecules 2004, 9(10), 849-859; https://doi.org/10.3390/91000849 - 30 Sep 2004

Cited by 15 | Viewed by 8245

Abstract

Reaction of the title compound with hydrazine in the presence of air gives the 1-unsubstituted parent system via oxidative dehydrazination of the 1-hydrazino intermediate. The latter can be obtained in high yield by carrying out the hydrazinolysis step under inert gas, and it [...] Read more.

Reaction of the title compound with hydrazine in the presence of air gives the 1-unsubstituted parent system via oxidative dehydrazination of the 1-hydrazino intermediate. The latter can be obtained in high yield by carrying out the hydrazinolysis step under inert gas, and it is smoothly converted into [1,2,4]-triazolo[4’,3’:1,6]pyridazino[4,5- b]indoles. Full article

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162 KiB

Open AccessArticle

A Novel Approach to the Synthesis of 6-Amino-7-hydroxy-flavone

by Lijun Tang, Shufen Zhang, Jinzong Yang, Wentao Gao, Jian Cui and Tianyu Zhuang

Molecules 2004, 9(10), 842-848; https://doi.org/10.3390/91000842 - 30 Sep 2004

Cited by 25 | Viewed by 9885

Abstract

A novel approach to the synthesis of 6-amino-7-hydroxyflavone (1) is described. Reaction in acetone of 2′,4′-dihydroxy-5′-nitroacetophenone and benzoyl chloride in the presence of potassium carbonate affords 3-benzoyl-7-hydroxy-6-nitroflavone, which is cleaved in 5% ethanolic potassium hydroxide to give 1-(2,4-dihydroxy-5-nitrophenyl)-3- phenyl-1,3-propanedione. The 1,3-diketone thus formed [...] Read more.

A novel approach to the synthesis of 6-amino-7-hydroxyflavone (1) is described. Reaction in acetone of 2′,4′-dihydroxy-5′-nitroacetophenone and benzoyl chloride in the presence of potassium carbonate affords 3-benzoyl-7-hydroxy-6-nitroflavone, which is cleaved in 5% ethanolic potassium hydroxide to give 1-(2,4-dihydroxy-5-nitrophenyl)-3- phenyl-1,3-propanedione. The 1,3-diketone thus formed is then transformed into 7-hydroxy- 6-nitroflavone, followed by reduction to afford the title compound. Full article

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270 KiB

Open AccessArticle

Electron-Induced (EI) Mass Fragmentation is Directed by Intra- molecular H-Bonding in Two Isomeric Benzodipyran Systems

by Cornelis J. Van der Schyf and Stéphane Mabic

Molecules 2004, 9(10), 830-841; https://doi.org/10.3390/91000830 - 30 Sep 2004

Cited by 2 | Viewed by 10550

Abstract

The striking differences observed in the electron-induced (EI) mass fragmentationpathways of two isomeric benzodipyrans are attributable to hydrogen bonding in thesemolecules. In the "angular" isomer, 6-butyryl-5-hydroxy-2,2,8,8-tetramethyl-3,4,9,10-tetra-hydro-2H,8H-benzo[1,2-b:3,4-b¹]dipyran (2), H-bonding occurs between the aromatic OHgroup and the alpha carbonyl moiety contained in the [...] Read more.

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

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170 KiB

Open AccessArticle

Synthesis and Reactions of N-Methylbenzylammonium Fluorochromate(VI) on Silica Gel, a Selective and Efficient Heterogeneous Oxidant

by M. Z. Kassaee, S. Z. Sayyed-Alangi and H. Sajjadi-Ghotbabadi

Molecules 2004, 9(10), 825-829; https://doi.org/10.3390/91000825 - 30 Sep 2004

Cited by 27 | Viewed by 9501

Abstract

N-Methylbenzylammonium fluorochromate(VI) (MBAFC) is easily synthesized by addition of N-methylbenzylamine to an aqueous solution of CrO3 and HF. MBAFC shows selectivity in the oxidation of aryl alcohols to their corresponding aldehydes and ketones under mild conditions. The durability, ease of work up and [...] Read more.

N-Methylbenzylammonium fluorochromate(VI) (MBAFC) is easily synthesized by addition of N-methylbenzylamine to an aqueous solution of CrO3 and HF. MBAFC shows selectivity in the oxidation of aryl alcohols to their corresponding aldehydes and ketones under mild conditions. The durability, ease of work up and efficiency of MBAFC are considerably increased upon its absorption on silica gel. Full article

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194 KiB

Open AccessArticle

Synthesis of Novel Azo Schiff Bases and Their Antibacterial and Antifungal Activities

by A. A. Jarrahpour, M. Motamedifar, K. Pakshir, N. Hadi and M. Zarei

Molecules 2004, 9(10), 815-824; https://doi.org/10.3390/91000815 - 30 Sep 2004

Cited by 168 | Viewed by 13339

Abstract

Ten new azo Schiff bases 5a-h and 7a-b were prepared in excellent yields via the condensation of different aromatic amines and a new azoaldehyde, 2-hydroxy-3- methoxy-5-(4-methoxyphenylazo)benzaldehyde (4) by two different methods. All new compounds were tested against five microorganisms: Staphylococcus aureus (Gram positive [...] Read more.

Ten new azo Schiff bases 5a-h and 7a-b were prepared in excellent yields via the condensation of different aromatic amines and a new azoaldehyde, 2-hydroxy-3- methoxy-5-(4-methoxyphenylazo)benzaldehyde (4) by two different methods. All new compounds were tested against five microorganisms: Staphylococcus aureus (Gram positive and methicillin resistant), Bacillus subtilis (Gram positive), Kelebsiella pneumonia, Pseudomonas aeruginosa and Escherichia coli (all Gram negative). Compounds 4, 5a, 5c, 5d and 5g were moderately active against Staphylococcus aureus and Bacillus subtilis. Compound 7b was highly active against Bacillus subtilis and moderately active against Staphylococcus aureus. Other compounds were inactive against these strains of bacteria. The antifungal activities of these compounds were also tested against eight different fungal species. None of them were active against the fungi species tested. Full article

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Molecules, Volume 9, Issue 10 (October 2004) – 10 articles , Pages 815-901

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