Protonation and silver(I) complex-formation equilibria of some amino-alcohols

Formation constants of the silver(I) complexes with some amino-alcohols have been determined at 25 degrees C in 0.5 M KNO(3) by means of two independent potentiometric measurements employing glass and silver electrode. The ligands considered are: sec-butylamine, 2-amino-1-propanol, 2-amino-1-methoxy-propane, 2-amino-2-methyl-1-propanol, 2-amino-1-butanol, 2-amino-1-pentanol, 2-amino-1-hexanol, 2-amino-1,3-propanediol, 2-amino-1,3-hexandiol, 2-amino-2-methyl-1,3-propanediol and Tris(hydroxymethyl)-aminomethane. Protonation constants of the selected ligands have also been determined. Calculations were made using HYPERQUAD computer program. The influence exerted by the introduction of hydroxy groups and by the presence of alkyl residuals in the ligand structure on the formation equilibria, is discussed.     

4(3H)-Quinazolinones containing heterocyclic group in position 3

The corresponding 2,3-substituted 4(3H)-quinazolinones were obtained in the reactions of 2-methyl- and 2-phenyl-4-oxo-3,1-benzoxazines with 1-amino-1,2,4-triazole, 4-amino-2,3-dimethyl-1-phenyl-5-pyrazolone, 2-amino-5-ethyl-1,3,4-thiadiazole, 3-amino-6,6-dimethyl-4-oxo-4,5,6,7-tetrahydroindazole, 1-amino-3-cyano-4,6-dimethyl-2-pyridone, and 1-amino-3-cyano-6-phenyl-4-trifluoromethyl-2-pyridone. The formation of N-benzolyanthranilamides in the reactions of 2-phenyl-4-oxo-3,1-benzoxazine with 2-amino-5-ethyl-1,3,4-thiadiazole and 1-amino-3-cyano-6-phenyl-4-trifluoromethyl-2-pyridones was exceptional. The structures of two of the products have been confirmed by X-ray crystallography.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 936–943, July, 2000.     

Deamination,involving ring opening,in reactions of 1-aminopurinium mesitylenesulfonates with methanolic amonia

On reaction of 1-aminopurinium mesitylenesulfonates with methanolec ammonia N-deamintion occurs. For 1-amino-, 1-amino-8-(methylthio)-, 1-amino-8-phenyl-, 1-amino-2-methyl-, 1-amino-6-methyl- and 1-amino-8-phenyl-9-methyl-purinium mesitylenesulfonate this reaction proceeds for at least 75% via ring opening as shown by the isolation of 1-¹⁵N-labelled purines when ¹⁵N-labelled methanolic ammonia was used. 1-Amino-9-methylpurinium mesitylenesulfonate gave N-deamination without ring opening. The reaction of 1-amino-6-(methylthio)purinium mesitylenesulfonate with methanolic ammonia involves, besides deamination, partial substitution of the methylthio group; no ring opening is involved. However, ring opening followed by substitution occurs in the reaction of 1-amino-2-(methylthio)purinium mesitylenesulfonate; the reaction proceeds via an adduct at position 2.     

Synthesis of 5-amino-1-(aminothioformyl)-1, 2, 4-triazoles

By the reaction of 5-amino-1, 2, 4-triazoles with benzoyl isothiocyanate we have synthesized 5-amino-1-(benzoylaminothioformyl)-1, 2, 4-triazoles, which form 5-amino-1-(aminothioformyl)-1, 2, 4-triazoles on alkaline hydrolysis.     

1-Amino-3-alkyl-2-(methylthio)benzimidazolium salts: synthesis,reaction with CH-acid anions,and conversion to pyrazolo[1,5-a]benzimidazole derivatives

For the first time, 1-amino-3-alkylbenzimidazolinethiones were obtained by heating 1-amino-3-alkylbenzimidazolium iodides with sulfur in the presence of triethylamine. They were converted to 1-amino-3-alkyl-2-(methylthio)benzimidazolium salts, which, during reaction with CH-acid onions, gave the corresponding 1-amino-3-alkyl-2-methylenebenzimidazoline derivatives. Under conditions of alkaline or acid catalysis, the latter derivatives cyclized to 2-amino- or 2-hydroxy derivatives of pyrazolo[1,5-a]benzimidazole.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 205–214, February, 1992.     

Piperidine-mediated synthesis of thiazolyl chalcones and their derivatives as potent antimicrobial agents

A series of new thiazolyl chalcones, 1-[2-amino-4-methyl-1,3-thiazol-5-yl]-3-aryl-prop-2-en-1-one were prepared by piperidine mediated Claisen-Schmidt condensation of thiazolyl ketone with aromatic aldehyde. These chalcones on cyclisation gave 2-amino-6-(2-amino-4-methyl-1,3-thiazol-5-yl)-4-aryl-4H-pyridine-3-carbonitrile and 2-amino-6-(2-amino-4-methyl-1,3-thiazol-5-yl)-4-aryl-4H-pyran-3-carbonitrile. The result showed that the compounds exhibited marked potency as antimicrobial agents.     

N-monosubstituted 6-Aminomethylene-5-oxo-2-phenyl-5,6,7,8-tetrahydroquinazolines

We have obtained the corresponding N-monosubstituted 6-aminomethylene-5-oxo-2-phenyl-5,6,7,8-tetrahydroquinazolines by transamination of 6-dimethylaminomethylene-5-oxo-2-phenyl-5,6,7,8-tetrahydroquinazoline with histamine, tryptamine, 3-(1-imidazolyl)- and 3-(4-morpholyl)-propylamines, 4-amino-1-benzylpiperidine, 2-(1-naphthylamino)ethylamine, 2-pyridylmethylamine, 4-chlorobenzylamine, ethanolamine, 1-aminoadamantane, remantadine, 2-aminodimedone, aniline, 3-trifluoromethylaniline, 4-aminoantipyrine, 2-aminobenzimidazole, 2-amino-5-methylbenzothiazole, 7-amino-4-methylcoumarin, 1-amino-4-methylpiperazine, 2-(2-aminophenyl)benzimidazole, 3-(4-aminophenylamino)-2-cyano-5,5-dimethylcyclohex-2-en-1-one, and 3-amino-2-(2-hydroxyethyl)-6,6-dimethyl-4-oxo-4,5,6,7-tetrahydroindazole. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1230–1235, August, 2005.     

Complex formation equilibria of some beta-amino-alcohols with lead(II) and cadmium(II) in aqueous solution

A study of complex formation equilibria of some beta-amino-alcohols with lead(II) and cadmium(II) ions at 25 degrees C and in 0.5 M KNO(3) is reported. The amino-alcohols considered are 2-amino-1-propanol, 2-amino-1-butanol, 2-amino-1-pentanol and 2-amino-1,3-propanediol. sec-Buthylamine and 2-amino-1-methoxy-propane have been also considered for comparison. The results are discussed in terms of ligand structure, paying attention to the number of hydroxyl groups and to the length of the alkyl residual. A weak contribution of the alcoholic oxygen in the coordination of cadmium(II) and the presence of a mixed hydroxyl species in lead(II) containing systems are hypothesized.     

Reaction of pyrylium salts with heterocyclic amines

It has been established that in the reaction of 2, 4, 6-trimethylpyrylium perchlorate with 2-, 3-, and 4-aminopyridines, cytosine, adenine, guanine, and the corresponding nucleosides, and also with 2-amino-1-methylbenzimidazole, 2-amino-4-methylthiazole, 2-amino-4-phenylthiazole, 2-amino-6-bromobenzo-thiazole, and 2-amino-6-methoxybenzothiazole, either the corresponding quaternary pyridinium salt is formed or the pyrylium ring opens, depending on the basicity of the amino group.     

Synthesis, IR, UV/vis-, (1)H NMR and DFT study of chelatophore functionalized 1,3-benzoxazinone spiropyrans

Six novel functionalized spiropyran's derivatives of 2H-1,3-benzoxazinone series were synthesized by introducing the substituents with chelating ability into 2H-chromene part of the 8'-formyl-7'-hydroxy-3-methyl-4-oxo-3,4-dihydro-2H-1,3-benzoxazine-2-spiro-2'-[2H]-chromene (I) by condensation with 2-aminophenol, 2-amino-4-methylphenol, 2-amino-4-nitrophenol, 2-amino-1-methylbenzimidazole, 4-amino-4H-1,2,4-triazole, N-(4-aminophenyl)acetamide. (1)H NMR, UV/vis, IR spectroscopy combined with quantum-chemical calculations employing density functional theory (DFT) were used to study their structure. All substances, except 2-amino-4-nitrophenol derivative exist in solid state and in solution solely in closed spiroform, while the mentioned one undergoes partial spiropyran ring opening. In DMSO solution NMR spectra show ratio of 2:1 of closed and opened form, correspondingly.     

2-氨基-6-三氟甲基嘧啶衍生物的合成及表征

近几年,含嘧啶结构单元的高效低毒农药层出不穷,如用作杀菌剂的嘧啶胺类、嘧啶腺类及嘧啶丙烯酸酯类,除草剂有嘧啶磺酰脲类、嘧啶水杨酸类、酰基(硫)脲类及三唑并嘧啶磺酰脲类。将含氟基团引入杂环结构是新药创制的一个发展方向,     

Stereoselective synthesis of β-functionalized α-aminophosphonates via aziridinium ions

1,2-Diamino-, 1-amino-2-hydroxy- and 1-amino-2-chloro-2-phenylethylphosphonates were obtained in a stereo- and regioselective manner from 2-amino-1-hydroxy-2-phenylethylphosphonate through the intermediacy of an aziridinium ion.     

Transformations of 1-amino-2-(3-hydroxyalk-1-ynyl)-9,10-anthraquinones in the presence of amines

When heated in piperidine, 1-amino-2-(3-hydroxyalk-1-ynyl)-9,10-anthraquinones undergo cyclization into 2-(1-hydroxyalkyl)naphtho[2,3-g]indole-6,11-diones. In contrast, 1-amino-2-(3-hydroxy-3-phenylpropynyl)-9,10-anthraquinone reacts with primary and secondary amines to give the corresponding 1-amino-2-(1-amino-2-benzoylvinyl)-9,10-anthraquinones, which undergo cyclization into 4-dialkylamino- or 4-alkylamino-2-phenylnaphtho[2,3-h]quinoline-7,12-diones. Heating of the starting phenylpropynol with Et₃N causes its dehydrogenation and isomerization.     

Preparation of aminotriazole-thione derivatives from n-aryl-n-carboxyethyl-β-alanines

Depending on the substituents in the aryl moiety, the fusion of N-aryl-N-ethoxycarbonyl-β-alanines with thiocarbohydrazide gives di- or monotriazole derivatives, namely, 4-amino-(2-{[2-(4-amino-5-thioxo-4,5-dihydro-1H-1,2,4-triazol-3-yl)ethyl]anilino}ethyl)-4,5-dihydro-1H-1,2,4-triazole-5-thiones, 1-[2-(4-amino- 5-thioxo-4,5-dihydro-1H-1,2,4-triazol-3-yl)ethyl]-2,3-dihydroquinolin-4(1H)-ones, 4-amino-3-[2-(4-methylanilino))ethyl]-4,5-dihydro-1H-1,2,4-triazole-5-thione and 4-amino-3-[2-(4-ethoxyanilino)-ethyl]-4,5-dihydro-1H-1,2,4-triazole-5-thione. A ditriazolethione derivative was also obtained from the diethyl ester of N-ethoxycarbonyl-N-(4-ethoxyphenyl)- β-alanine.     

Acetyl ketene aminals in Nenitzescu reaction

Nenitzescu reaction of acetyl ketene aminals (N,N-acetals) was investigated. The interaction of 2-acetyl-1-amino-1-anilinoethene with benzoquinone gave 3-acetyl-2-amino-7a-hydroxy-1-phenyl-5,7a-dihydro-1H-indol-5-one, which was then transformed into 3-acetyl-2-amino-6-chloro-5-hydroxy-1-phenylindole. The reaction of benzoquinone with 2-acetyl-1-amino-1-benzoylaminoethene led to the corresponding hydroquinone-adduct which was oxidized to 4-acetylamino-5-(2,5-dihydroxyphenyl)-2-phenyloxazole. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 160–165, January, 1999.     

Complex formation equilibria of some β-amino-alcohols with lead(II) and cadmium(II) in aqueous solution

A study of complex formation equilibria of some β-amino-alcohols with lead(II) and cadmium(II) ions at 25°C and in 0.5 M KNO₃ is reported. The amino-alcohols considered are 2-amino-1-propanol, 2-amino-1-butanol, 2-amino-1-pentanol and 2-amino-1,3-propanediol. sec-Buthylamine and 2-amino-1-methoxy-propane have been also considered for comparison. The results are discussed in terms of ligand structure, paying attention to the number of hydroxyl groups and to the length of the alkyl residual. A weak contribution of the alcoholic oxygen in the coordination of cadmium(II) and the presence of a mixed hydroxyl species in lead(II) containing systems are hypothesized.     

The hydrogen bonding and amino-imino tautomerization of the alkoxy-aminopyridines and amino-methoxypyrimidines with acetic acid The effects of the methoxy group

The hydrogen bonding and amino-imino tautomerization of the systems of 2-amino-3-methoxypyridine (2A3MOP), 2-amino-6-methoxypyridine (2A6MOP), 2-amino-6-n-propoxypyridine (2A6NPOP), 2-amino-6-iso-propoxypyridine(2A6IPOP), 2-amino-4-methoxypyrimidine (2A4MOPM), 4-amino-2-methoxypyrimidine (4A2OPM), 4-amino-6-methoxypyrimidine (4A6MOPM), 2-amino-4-methoxy-6-methylpyrimidine (MMPM), and 2-amino-4,6-dimethoxypyrimidine (DMOPM), with acetic acid (AcOH) in n-hexane at room temperature were investigated by means of the UV absorption and fluorescence spectroscopy. From the UV absorption spectra the presence of the dual hydrogen-bonded complexes that linked by a 1:1 molar ratio with AcOH were found, since the enthalpy changes accompanying the hydrogen bond formation between 2A3MOP, 2A4MOPM, 4A2MOPM, 4A6MOPM, or MMPM, and AcOH were ca. 42.8-61.1kJmol(-1) in n-hexane. The fluorescence spectra of the 2A3MOP/AcOH, 2A4MOPM/AcOH, 4A6MOPM/AcOH, and MMPM/ AcOH systems revealed that the imino-tautomers were produced through double proton transfer in the amino hydrogen-bonded 1:1 complexes in the S1 state, but the imino-tautomer formation for the 4A2MOPM/AcOH system was not found on account of the steric hindrance due to the inversion of the methoxy group in the S1 state. The imino-tautomer for the MMPM/AcOH system fluoresces most intensely among these systems investigated. On the other hand, not only the formation of the corresponding amino dual hydrogen-bonded complex and but also that of imino-tautomer were prevented for the 2A6MOP/AcOH, 2A6NPOPM/AcOH, 2A6IPOP/AcOH, and DMOPM/AcOH systems, because of the steric hindrance of the methoxy group in both the S0 and S1 states. The theoretical approaches by an ab initio molecular orbital calculation were in accord with the experimental results.     

Activated nitriles in heterocyclic synthesis. A novel synthesis of pyrazolo[1,5-a]pyrimidines and pyrano[2,3-c]pyrazoles

Several new pyrazolo[1,5-a]pyrimidines and pyrano[2,3-c]pyrazoles were synthesized viathe reaction of the cinnamonitrile derivatives 1a-c with 5-amino-3-phenylpyrazole ( 1 ), 3-amino-2-pyrazolin-5-one ( 2 ) and 3-amino-1-phenyl-2-pyrazolin-5-one ( 22 ).     

Zur Synthese sulfonierter Derivate von 4-Amino-1,3-dimethylbenzol und 2-Amino-1,3-dimethylbenzol

Syntheses of Sulfonated Derivatives of 4-Amino-1, 3-dimethylbenzene and 2-Amino-1, 3-dimethylbenzene Direct sulfonation of 4-amino-1, 3-dimethylbenzene (1) and sulfonation of 4-nitro-1,3-dimethylbenzene ( 4 ) to 4-nitro-1,3-dimethylbenzene-6-sulfonic acid ( 3 ) followed by reduction yield 4-amino-1,3-dimethylbenzene-6-sulfonic acid ( 2 ). The isomeric 5-sulfonic acid ( 5 ) however is prepared solely by baking the acid sulfate salt of 1 . Reaction of sulfur dioxide with the diazonium chloride derived from 2-amino-4-nitro-1,3-dimethylbenzene ( 7 ) leads to 4-nitro-1,3-dimethylbenzene-2-sulfonyl chloride ( 8 ), which is successively hydrolyzed to 4-nitro-1,3-dimethylbenzene-2-sulfonic acid ( 9 ) and reduced to 4-amino-1, 3-dimethylbenzene-2-sulfonic acid ( 6 ). Treatment of 4-amino-6-bromo-1,3-dimethylbenzene ( 12 ) and 4-amino-6-chloro-1, 3-dimethylbenzene ( 13 ), the former obtained by reduction of 4-chloro-6-nitro-1,3-dimethyl-benzene ( 10 ) and the latter from 4-chloro-6-nitro-1, 3-dimethylbenzene ( 11 ), with oleum yield 4-amino-6-bromo-1,3-dimethylbenzene-2-sulfonic acid ( 14 ) and 4-amino-6-chloro-1,3-dimethylbenzene-2-sulfonic acid ( 15 ) respectively; subsequent carbon-halogen hydrogenolyses of 14 and 15 lead also to 6 (Scheme 1). Baking the acid sulfate salt of 2-amino-1, 3-dimethylbenzene ( 17 ) gives 2-amino-1, 3-dimethylbenzene-5-sulfonic acid ( 16 ), whereas the isomeric 4-sulfonic acid ( 18 ) can be prepared by either of the following three possible pathways: Sulfonation of 2-nitro-1,3-dimethylbenzene ( 20 ) to 2-nitro-1,3-dimethylbenzene-4-sulfonic acid ( 21 ) followed by reduction or sulfonation of 2-acetylamino-1,3-dimethylbenzene ( 19 ) to 2-acetylamino-1,3-dimethylbenzene-4-sulfonic acid ( 22 ) with subsequent hydrolysis or direct sulfonation of 17 . Further sulfonation of 18 yields 2-amino 1,3-dimethylbenzene-4,6-disulfonic acid ( 23 ), the structure of which is independently confirmed by reduction of unequivocally prepared 2-nitro- 1,:3-dimethylbenzene-4,6-disulfonic acid ( 24 )(Scheme 2).     

An improved synthesis of butyl 4-[(4-amino-5-chloro-2-methoxybenzoyl)amino]-1-piperidineacetate (AU-224).

A new and facile route for the synthesis of the novel gastrointestinal prokinetic butyl 4-[(4-amino-5-chloro-2-methoxybenzoyl)amino]-1-piperidineacetate (1b), which exhibited potent gastro- and colon-prokinetic activities by oral administration without significant side effects, was established. The key intermediate, butyl 4-amino-1-piperidineacetate (16), was prepared from commercially available 4-amino-1-benzylpiperidine (2) in a high yield with four steps. Compound 1b was prepared by condensation of commercially available 4-amino-5-choloro-2-methoxybenzoic acid (7) with 16 in 84% yield. This improved synthetic route was appropriate for large-scale synthesis of 1b.