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p. 297-309
Received: 27 September 2002; in revised form: 8 March 2003 / Accepted: 10 March 2003 / Published: 31 March 2003
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| Download PDF Full-text (397 KB) 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 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.
p. 310-317
Received: 22 January 2003; in revised form: 14 March 2003 / Accepted: 17 March 2003 / Published: 31 March 2003
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| Download PDF Full-text (325 KB) 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. All new compounds have been characterized by FAB (+) spectrometry and NMR spectroscopy. 13 C-NMR spectra are crucial to firmly establish the thiol structure of the title ligands.
p. 318-321
Received: 18 August 2002; in revised form: 16 February 2003 / Accepted: 12 March 2003 / Published: 31 March 2003
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| Download PDF Full-text (175 KB) 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.
p. 322-332
Received: 18 December 2002; in revised form: 29 March 2003 / Accepted: 30 March 2003 / Published: 31 March 2003
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| Download PDF Full-text (351 KB) 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 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 .
p. 333-341
Received: 2 December 2002; in revised form: 13 January 2003 / Accepted: 9 January 2003 / Published: 31 March 2003
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| Download PDF Full-text (345 KB) 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 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.
p. 342-348
Received: 12 December 2002; in revised form: 11 March 2003 / Accepted: 27 March 2003 / Published: 31 March 2003
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| Download PDF Full-text (224 KB) 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, but the overall yields of the reactions are considerably lower.
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