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

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Research

Open AccessArticle Synthesis of Novel Azo Schiff Bases and Their Antibacterial and Antifungal Activities
Molecules 2004, 9(10), 815-824; doi:10.3390/91000815
Received: 19 January 2004 / Accepted: 26 February 2004 / Published: 30 September 2004
Cited by 63 | PDF Full-text (194 KB) | HTML Full-text | XML Full-text
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
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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
Open AccessArticle Synthesis and Reactions of N-Methylbenzylammonium Fluorochromate(VI) on Silica Gel, a Selective and Efficient Heterogeneous Oxidant
Molecules 2004, 9(10), 825-829; doi:10.3390/91000825
Received: 28 June 2004 / Revised: 11 June 2004 / Accepted: 15 June 2004 / Published: 30 September 2004
Cited by 20 | PDF Full-text (170 KB) | HTML Full-text | XML Full-text
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
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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
Open AccessArticle Electron-Induced (EI) Mass Fragmentation is Directed by Intra- molecular H-Bonding in Two Isomeric Benzodipyran Systems
Molecules 2004, 9(10), 830-841; doi:10.3390/91000830
Received: 30 March 2004 / Accepted: 29 July 2004 / Published: 30 September 2004
Cited by 1 | PDF Full-text (270 KB) | HTML Full-text | XML Full-text
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
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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
Open AccessArticle A Novel Approach to the Synthesis of 6-Amino-7-hydroxy-flavone
Molecules 2004, 9(10), 842-848; doi:10.3390/91000842
Received: 8 May 2004 / Accepted: 8 July 2004 / Published: 30 September 2004
Cited by 10 | PDF Full-text (162 KB) | HTML Full-text | XML Full-text
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
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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
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
Molecules 2004, 9(10), 849-859; doi:10.3390/91000849
Received: 8 June 2004 / Accepted: 18 June 2004 / Published: 30 September 2004
Cited by 10 | PDF Full-text (200 KB) | HTML Full-text | XML Full-text
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
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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
Open AccessArticle Synthesis and Spectroscopic Characterization of New Schiff Bases Containing the Benzo-15-Crown-5 Moiety
Molecules 2004, 9(10), 860-866; doi:10.3390/91000860
Received: 4 June 2004 / Accepted: 19 July 2004 / Published: 30 September 2004
Cited by 10 | PDF Full-text (185 KB) | HTML Full-text | XML Full-text
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
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.
Molecules 2004, 9(10), 867-875; doi:10.3390/91000867
Received: 22 July 2004 / Accepted: 3 September 2004 / Published: 30 September 2004
Cited by 19 | PDF Full-text (190 KB) | HTML Full-text | XML Full-text
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
Open AccessArticle Crystal Structure and Characterization of the Dinuclear Cd(II) Complex [Cd(H2O)2(ο-HOC6H4COO)2]2
Molecules 2004, 9(10), 876-882; doi:10.3390/91000876
Received: 18 June 2004 / Accepted: 21 July 2004 / Published: 30 September 2004
Cited by 10 | PDF Full-text (399 KB) | HTML Full-text | XML Full-text
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
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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
Open AccessArticle Theoretical Study of Some Nitrososulfamide Compounds with Antitumor Activity
Molecules 2004, 9(10), 883-893; doi:10.3390/91000883
Received: 25 March 2004 / Accepted: 21 July 2004 / Published: 30 September 2004
Cited by 2 | PDF Full-text (202 KB) | HTML Full-text | XML Full-text
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
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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
Open AccessArticle Fused Heterocycles: Synthesis of Some New Imidazo[1,2-a]- pyridine Derivatives
Molecules 2004, 9(10), 894-901; doi:10.3390/91000894
Received: 4 August 2004 / Accepted: 13 September 2004 / Published: 30 September 2004
Cited by 14 | PDF Full-text (146 KB) | HTML Full-text | XML Full-text
Abstract
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
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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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