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Molecules, Volume 8, Issue 3 (March 2003), Pages 297-348

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Research

Open AccessArticle Immobilization of 1-[N-(M-Nitrobenzoyl)-α-D,L-Asparagyl]-2-Benzylbenzimidazole on Gellan
Molecules 2003, 8(3), 297-309; doi:10.3390/80300297
Received: 27 September 2002 / Revised: 8 March 2003 / Accepted: 10 March 2003 / Published: 31 March 2003
Cited by 3 | PDF Full-text (397 KB) | HTML Full-text | XML Full-text
Abstract
This paper studies the dicyclohexylcarbodiimide activated coupling reaction through ester-type covalent bonds of an oxazolone derived from N-(m-nitrobenzoyl)-L-asparagic acid, ring opened with 2-benzylbenzimidazole, on gellan. Based on a centered, rotatory, composed, second order experimental design, the regression equation describing the dependence of the
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This paper studies the dicyclohexylcarbodiimide activated coupling reaction through ester-type covalent bonds of an oxazolone derived from N-(m-nitrobenzoyl)-L-asparagic acid, ring opened with 2-benzylbenzimidazole, on gellan. Based on a centered, rotatory, composed, second order experimental design, the regression equation describing the dependence of the amount of drug chemically bonded to the support on the reaction parameters is obtained. The efficiency of the coupling reaction over the variation domain established is maximum when the parameters’ highest values are used. The kinetics of the drug’s release from the support are studied under alkaline hydrolysis conditions. Full article
Open AccessArticle Sulfur Bridged Multidentate Ligands Based on (Bi)pyridyl-(Bi)-1,3,4-Thiadiazolyl Conjugates
Molecules 2003, 8(3), 310-317; doi:10.3390/80300310
Received: 22 January 2003 / Revised: 14 March 2003 / Accepted: 17 March 2003 / Published: 31 March 2003
Cited by 2 | PDF Full-text (325 KB) | HTML Full-text | XML Full-text
Abstract
The synthesis of a series of mixed (bi)pyridyl/(bi)1,3,4-thiadiazolyl ligands, derived from the condensation of 2-mercapto-5-methylthio-1,3,4-thiadiazole or 5-mercapto-5'-methylthio-2,2'-bi-1,3,4-thiadiazole with 2,6-bis(chloromethyl)pyridine or 6,6’-bis(chloromethyl)-2,2’-bipyridine (compounds L1–L4), and of 2,5-dimercapto-1,3,4-thiadiazole or 5,5'-dimercapto-2,2'-di-1,3,4-thiadiazole with picolyl chloride hydrochloride or 6-chloromethyl-6'-methyl-2,2'-bipyridine (compounds L5–L8) in the presence of triethylamine is described.
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The synthesis of a series of mixed (bi)pyridyl/(bi)1,3,4-thiadiazolyl ligands, derived from the condensation of 2-mercapto-5-methylthio-1,3,4-thiadiazole or 5-mercapto-5'-methylthio-2,2'-bi-1,3,4-thiadiazole with 2,6-bis(chloromethyl)pyridine or 6,6’-bis(chloromethyl)-2,2’-bipyridine (compounds L1–L4), and of 2,5-dimercapto-1,3,4-thiadiazole or 5,5'-dimercapto-2,2'-di-1,3,4-thiadiazole with picolyl chloride hydrochloride or 6-chloromethyl-6'-methyl-2,2'-bipyridine (compounds L5–L8) in the presence of triethylamine is described. All new compounds have been characterized by FAB (+) spectrometry and NMR spectroscopy. 13C-NMR spectra are crucial to firmly establish the thiol structure of the title ligands. Full article
Open AccessArticle Modified Methods for the Synthesis of Triazinyl Fluorescent Brightener Intermediates
Molecules 2003, 8(3), 318-321; doi:10.3390/80300318
Received: 18 August 2002 / Revised: 16 February 2003 / Accepted: 12 March 2003 / Published: 31 March 2003
Cited by 4 | PDF Full-text (175 KB) | HTML Full-text | XML Full-text
Abstract The production of triazinyl fluorescent brightener intermediates in high yields is described. The method involves a simplified work-up for the preparation of 4-nitro-toluene-2-sulfonic acid and the use of diethylene glycol instead of water in the preparation of 4,4'-dinitrostilbene-2,2'-disulfonic acid. Full article
Open AccessArticle The Use of 4-(3,4-Dichlorophenyl)-4-Oxo-2-(4-Antipyrinyl)-Butanoic Acid in the Preparation of Some New Heterocyclic Compounds With Expected Biological Activity
Molecules 2003, 8(3), 322-332; doi:10.3390/80300322
Received: 18 December 2002 / Revised: 29 March 2003 / Accepted: 30 March 2003 / Published: 31 March 2003
Cited by 13 | PDF Full-text (351 KB) | HTML Full-text | XML Full-text
Abstract
Reaction of 4-oxo-4-(3,4-dichlorophenyl)-2-butenoic acid (1) with antipyrin (2) gave the corresponding butanoic acid 3. Reaction of 3 with hydrazines gave the pyridazinone derivatives 5a,b. Compounds 5a,b were used to prepare the corresponding dithio derivatives. Reaction of 5a with POCl3 unexpectedly gave the
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Reaction of 4-oxo-4-(3,4-dichlorophenyl)-2-butenoic acid (1) with antipyrin (2) gave the corresponding butanoic acid 3. Reaction of 3 with hydrazines gave the pyridazinone derivatives 5a,b. Compounds 5a,b were used to prepare the corresponding dithio derivatives. Reaction of 5a with POCl3 unexpectedly gave the chloropyridazine derivative 7, which is used to prepare the corresponding thio derivative. The hitherto unknown reactions of this chloro derivative with 2-amino-3-carbethoxy-4,5-dimethylthiophene and 2-amino-3-carbethoxy tetrahydrobenzothiophene have now been described. The behaviour of the chloro derivative toward hydrazine hydrate, sodium azide and anthranilic acid was also studied. Some of the new compounds showed antimicrobial and antifungal activities . Full article
Open AccessArticle New Routes to Pyridino[2,3-d]pyrimidin-4-one and Pyridino-[2,3-d]triazolino[4,5-a]pyrimidin-5-one Derivatives
Molecules 2003, 8(3), 333-341; doi:10.3390/80300333
Received: 2 December 2002 / Revised: 13 January 2003 / Accepted: 9 January 2003 / Published: 31 March 2003
Cited by 26 | PDF Full-text (345 KB) | HTML Full-text | XML Full-text
Abstract
2-Thioxopyrimidinyl-5-(N,N-dimethylamino)formamidine (5) and 1,3-diphenyltriazolo[3,4-d]pyrimidinyl-N,N-dimethylformamidine (14) were prepared by condensation of 6-amino-2-thioxo-1,3-dihydropyrimidin-4-one (2) and 7-amino-1,3-diphenyl-1,2,4-triazolo[4,3-a]pyrimidin-4-one (13) with dimethylformamide dimethyl-acetal (DMFDMA). Compound 5 reacts with acetophenone and 2-acetylthiophene to give the 2-thioxo-1,3-dihydropyridino[2,3-d]pyrimidin-4-ones 3a and 3b, respectively. Compounds 3a,b react with hydrazonoyl
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2-Thioxopyrimidinyl-5-(N,N-dimethylamino)formamidine (5) and 1,3-diphenyltriazolo[3,4-d]pyrimidinyl-N,N-dimethylformamidine (14) were prepared by condensation of 6-amino-2-thioxo-1,3-dihydropyrimidin-4-one (2) and 7-amino-1,3-diphenyl-1,2,4-triazolo[4,3-a]pyrimidin-4-one (13) with dimethylformamide dimethyl-acetal (DMFDMA). Compound 5 reacts with acetophenone and 2-acetylthiophene to give the 2-thioxo-1,3-dihydropyridino[2,3-d]pyrimidin-4-ones 3a and 3b, respectively. Compounds 3a,b react with hydrazonoyl halides 6,7 to give pyridino[2,3-d]triazolo[4,5-a]pyrimidin-4-ones 11a-d and not the isomeric structures 12a-d. Formamidines of type 14 react with ethyl cyanoacetate, malononitrile and benzoyl acetonitrile to give the 1,3-diphenyl-3a-hydropyridino[2,3-d]1,2,4-triazolo[4,5-a]pyrimidin-4-one derivatives 15a,b and 18, respectively. The structures of the newly synthesized compounds are established on the basis of chemical and spectroscopic evidences as well as their synthesis by alternative methods. Full article
Open AccessArticle Synthesis of New Cyano-Substituted bis-Benzothiazolyl Arylfurans and Arylthiophenes
Molecules 2003, 8(3), 342-348; doi:10.3390/80300342
Received: 12 December 2002 / Revised: 11 March 2003 / Accepted: 27 March 2003 / Published: 31 March 2003
Cited by 20 | PDF Full-text (224 KB) | HTML Full-text | XML Full-text
Abstract
The new compounds 2-[4-(6-cyanobenzothiazol-2-yl)phenyl]-5-(6-cyano-benzothiazol-2-yl)furan (6a) and 2-[4-(6-Cyanobenzothiazol-2-yl)phenyl]-5-(6-cyano-benzothiazol-2-yl)thiophene (6b) were synthesized by multi-step reactions from the corresponding 2-furan and 2-thiophene carboxaldehydes (route A), as well as from 2-furan and 2- thiophene carboxylic acids (route B). Route B involves one less step than route A,
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The new compounds 2-[4-(6-cyanobenzothiazol-2-yl)phenyl]-5-(6-cyano-benzothiazol-2-yl)furan (6a) and 2-[4-(6-Cyanobenzothiazol-2-yl)phenyl]-5-(6-cyano-benzothiazol-2-yl)thiophene (6b) were synthesized by multi-step reactions from the corresponding 2-furan and 2-thiophene carboxaldehydes (route A), as well as from 2-furan and 2- thiophene carboxylic acids (route B). Route B involves one less step than route A, but the overall yields of the reactions are considerably lower. Full article

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