Reaction of 5,6-diamino-1,3-dimethyluracil with arylideneacetones and arylidenecyclanones

The reaction of 5,6-diamino-1,3-dimethyluracil dihydrochloride with mono- and diarylideneacetones and with cyclohexanones give 2,4-disubstituted 1,7,9-triazaspiro[4,5]dec-1-ene-6,8,10-triones. It was found that arylidenecyclopentanones form only 5-azomethines with retention of the amino group at position 6 of the uracil ring.Kharkov State University, Kharkov 310077, Ukraine; e-mail: desenko@univer.kharkov.ua. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1230–1233, September, 1999.     

Reactions of 5,6-diamino-1,3-dimethyluracil with carbonyl compounds

The first step in the acid-catalyzed reaction of 5,6-diamino-1,3-dimethyluracil with carbonyl compounds is the formation of an azomethine at the 5-amino group. Chalcone derivatives undergo a further substitution; the 6-amino group is replaced by a hydroxyl group with subsequent ring closure and the formation of a 2,3-dihydro-1,5-oxazepine ring. Azomethines based on arylidenacetones forms 2,3-dihydropyrimidino[5,6-b]-1,5-diazepine derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 241–246, February, 1984.     

Quaternarisation de diméthyl-5,6 pyrazolidino[4,3-d )isoxazolines-2

We have determined the quaternization site of bicyclic molecules such as dimethyl-5,6 pyrazolidino[4,3-d]isoxazolines-2 containing two vicinal sp³ nitrogen atoms in a cycle and one sp² nitrogen atome in the other by spectral methods and by degradation of their corresponding iodomethylates. The quaternization takes place on one of the two sp³ nitrogen atoms and is controlled by steric effects.     

Synthesis of (S)-5,6-dibromo-tryptophan derivatives as building blocks for peptide chemistry

5,6-Dibromo-tryptophan is an interesting amino acid whose derivatives and analogues are found in a variety of highly bioactive natural compounds. Notwithstanding its relevance no data concerning this compound are found in the literature. Here an efficient pathway for the synthesis of 5,6-dibromo-tryptophan derivatives is reported. The reaction is performed by using 6-Br-isatin as starting material. Selective bromination at position 5 was followed by BH₃ reduction of the intermediate α-keto-amide and alkylation with Ser-OH in Ac₂O/AcOH. Optical resolution was effected by enzymatic de-acetylation of the obtained racemic mixture. Finally, in situ N^α-Boc protection of the optically pure S form yielded the desired N^α-Boc-(S)-5,6-dibromo-tryptophan.     

The chemistry of furazano-[3,4-b]pyrazine. 7. Properties of 5,6-diamino- and 5,6-dihydrazino-furazano[3,4-b]pyrazine

The reactions of 5,6-diamino- and 5,6-dihydrazinofurazano[3,4-b][yrazine that produce polycyclic or highly reactive compounds are reviewed. The furazan ring has a deactivating effect on the amine functions of these compounds. Dedicated to Professor Henk van der Plas on his 70th birthday. For No. 6, see [1]. Latvian Institute of Organic Synthesis, Riga LV-1006 Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 564–573, April, 1999.     

A new compound constructed from Keggin anions and Cu-5,6-diamino-1,10-phenanthroline complexes: synthesis,structure, and characterization

A new inorganic–organic hybrid based on polyoxometalate, [Cu₂(daphen)₂(H₂O)₄(PW₁₁W^VO₄₀)]?·?6H₂O (1) (daphen?=?5,6-diamino-1,10-phenanthroline), was synthesized hydrothermally and characterized by single-crystal X-ray diffraction, elemental analysis, infrared spectroscopy, and thermal analysis. Single-crystal X-ray diffraction analysis reveals that in 1 the Keggin anion [PW₁₂O₄₀]^4? is tetradentate, linking four Cu(II)-daphen fragments with its four terminal oxygen atoms in a plane; Cu²⁺ is coordinated by two terminal oxygen atoms of two [PW₁₂O₄₀]^4? anions, two water molecules, and two nitrogen atoms of the phen ring of a daphen, forming a polymeric layer. The 3-D architecture of the compound is further formed via hydrogen bonds between these layers. The daphen is bidentate chelating and does not participate in formation of hydrogen bonds. Redox of 1 was examined.     

Electrochemical oxidation of 2,6-diamino-8-purinol

Electrochemistry, spectroelectrochemistry and gas chromatography/mass spectrometry were used to determine the mechanism of oxidation of 2,6-diamino-8-purinol in phosphate buffer solutions. Experimental evidence indicates that the overall process is a 2 e⁻, 2 H⁺ reaction in which 2,6,-diamino-8-purinol is oxidized to form a diimine. The diimine is not stable and decomposes in a series of hydrolysis reactions to the final products 5-hydroxyghdantoin-5-carboxamide and 1-carbohydroxy2-,4,6,8-tetraaza-3,7-dioxo-4-ene-bicyclo[3,3,0]octane (BCA). Results are presented which show that the 2 e⁻ oxidation of 2,6-diamino-8-purinol proceeds in two 1 e⁻ steps and the evidence for the formation of a coupling product is discussed. A mechanism is proposed to explain the observed results.     

A new approach to the 2,5-diamino-5,6-dihydro-1H-pyrimidine-4-one derivatives: synthesis of TAN-1057A/B and analogs

TAN-1057A/B has shown potent activity against MRSA. A new approach to the 2,5-diamino-5,6-dihydro-1H-pyrimidine-4-one derivatives has been developed. TAN-1057A/B and its analogs were efficiently synthesized using this new approach.     

Studies on iron(III) complex with 5,6-diamino-1,3-dimethyluracil

Reaction of 5,6-diamino-1,3-dimethyluracil (DDU) with iron(III) ion gave a fine blue colouration due to the formation of Fe[(DDU—H)₃]·2HClO₄. An oxidation product (7), C₁₂H₁₂N₆O₄, was also isolated from the reaction mixture.     

Synthesis and properties of 4,6-diamino-3-cyano-2(1H)-pyridineselenone: Molecular and crystal structure of 2-allylseleno-4,6-diamino-3-cyanopyridine

Self-condensation of cyanoselenoacetamide gives 4,6-diamino-3-cyano-2(1H)pyridineselenone, which is regioselectively alkylated at the exocyclic heteroatom. The cisoid position of the Se-C bonds of the selenoallyl substituent relative to the N-C bond of the pyridine ring in the N¹C²SeC⁸ fragment favors cyclization into selenazolo[3,2-a]pyridinium salts.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2585–2590, November, 1989.     

Reactions of 5,6-diamino-1,3-dimethyluracil with halogen derivatives of chalcones

The reaction of 5,6-diamino-1,3-dimethyluracil with 1,3-diaryl-2,3-dibromopropan-1-ones gave -(5-amino-6-imino-1,3-dimethyluracil)chalcones, and conditions for their cyclocondensation to pyrimidinodiazepines were found. For substantiation of the reaction mechanism, the reaction of the diamine with other halogen derivatives of chalcones was studied. The IR, UV, and mass spectra of the synthesized compounds and their condensation products are discussed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 947–954, July, 1992.     

NMR studies of conformations and dynamic processes—1 : [24]cyclophanes with ethylene bridges

The conformations and dynamic processes in a series of relatively unstrained [2₄]paracyclophanes (with one, two or four -CH₂-CH₂-bridges) and some closely related compounds have been analysed. Their ¹NMR spectra have been recorded at low temperatures and the temperature dependence rationalised as being due to essentially two types of dynamic process-the torsional motion around the sp³-sp³ C-C bonds in the bridges, and the rotation around the sp²-sp³ C-C bonds adjacent to the benzene rings. The barriers to the former process are similar for the series of cyclophanes 1–6 and are due to steric and electronic interactions in the syn-oriented transition states. In cyclophanes 7–9, in which anti-orientations of the aromatic rings are possible, the barriers are lower. The latter process, involving the rotation of the benzene rings, becomes important at temperatures below 150 K and has not been further analysed.     

Ring-fluorinated naphthalene and indene synthesis via 6- and 5-endo-trig cyclizations of gem-difluoroalkenes by carbon nucleophiles

The intramolecular vinylic substitution of gem-difluoroalkenes is accomplished with sp³ and sp² carbon nucleophiles (2-arylethyllithium and aryllithium) in a 6-endo-trig and a normally disfavored 5-endo-trig fashion, leading to the synthesis of 3-fluoro-1,2-dihydronaphthalenes and 3-fluoroindenes, respectively. The dihydronaphthalenes are readily aromatized on treatment with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) to afford 2-fluoronaphthalenes.     

Near ultraviolet spectroscopic studies of 2,4-diamino-6-piperidinopyrimidine-3-oxide (minoxidil) and 2,4-diamino-6-piperidinopyrimidine (desoxyminoxidil)

The near u.v. spectra of 2,4-diamino-6-piperidinopyrimidine (desoxyminoxidil) and 2,4-diamino-6-piperidinopyrimidine-3-oxide (minoxidil) can be viewed as perturbed pyrimidine spectra. The u.v. properties of pyrimidine and a series of aminopyrimidines, specifically 2,4,6-triaminopyrimidine, are examined to obtain u.v. spectral assignments for desoxyminoxidil and minoxidil. Minoxidil and its desoxy counterpart have C_s symmetry, and all π → π* absorptions are allowed ¹A′ ← ¹A′ transitions. The two lowest energy π →- π* absorptions observed in minoxidil (262 nm, 292 nm) are tentatively assigned as very mild oxygen → pyrimidine ring charge-transfer transitions. Intensity decreases in protic solvents, and the results of simple Hückel molecular orbital calculations indicate that the 292 nm transition has more charge-transfer character than the 262 nm absorption. The protonated species of desoxyminoxidil and minoxidil have very similar u.v. spectra. This is due to the lack of oxygen-related charge transfer in protonated minoxidil, and the high probability that the positive charge resides in similar environments in the minoxidil and desoxyminoxidil molecular frameworks.     

5,6-二氢-5-氧杂-1,3-二氮杂菲衍生物的合成

以2,3-二氢-3-氧代-1,3-苯并(c)-α-吡喃(1)为起始原料, 在氢化钠作用下, 通过与羰基α-氢的Claisen缩合反应, 得到3-乙酰基-2,3-二氢-3-氧代-1,3-苯并(c)-α-吡喃(2), 所得β-二酮与脲、硫脲和脒衍生物分别进行缩合关环, 生成5,6-二氢-5-氧杂-1,3-二氮杂菲衍生物3和4. 在相同的条件下, 吡喃酮1与草酸二乙酯进行缩合反应, 给出3-乙氧乙二酰 基-2,3-二氢-3-氧代-1,3-苯并(c)-α-吡喃(5), 选择3-氨基吡唑、2-氨基咪唑、3-氨基三唑、2-氨基苯并咪唑和3,5-二氨基吡唑-4-偶氮苯与5缩合, 分别环合成5,6-二氢-5-氧杂-1,3-二氮杂菲并和五元含氮杂环衍生物6～10. 所合成的新化合物均经核磁共振光谱、红外光谱及元素分析证明其结构.     

In situ electrode modification for direct differential pulse polarography of 2,6-diaminopurine and its metabolite, 2,6-diamino-8-purinol

Preferential adsorption of allopurinol (1H-pyrazolo-[3,4-d]-pyrimidin-4-ol) at graphite electrodes from pH 7.0 phosphate buffer solutions of 2,6-diaminopurine and 2,6-diamino-8-purinol allowed in situ electrode modification. Modified electrodes were applied to the simultaneous determination of 2,6-diaminopurine and 2,6-diamino-8-purinol in phosphate buffer at pH 7.0. Differential pulse polarography allowed both compounds to be quantified in the concentration range 1 × 10^?6–5 × 10^?4 M. The relative standard deviation of the peak current is about 10%. Calibration curve characteristics are C (μM) = 0.0094 ± 0.0002 I (μA) + 0.22 ± 0.07 μA, with r = 0.9985 and C (μM) = 0.0065 ± 0.0001 I (μA) + 0.03 ± 0.04 μA with r = 0.9990 for 2,6-diamino-8-purinol and 2,6-diaminopurine, respectively.     

Reaction of 1-alkyl/aryl-3-amino-1H,3H-quinoline-2,4-diones with urea. Synthetic route to novel 3-(3-acylureido)-2,3-dihydro-1H-indol-2-ones, 4-alkylidene-1′H-spiro[imidazolidine-5,3′-indole]-2,2′-diones, and 3,3a-dihydro-5H-imidazo[4,5-c]quinoline-2,4-diones

1-Substituted 3-alkyl/aryl-3-amino-1H,3H-quinoline-2,4-diones react with urea in boiling acetic acid to give products depending on the type of substitution in position 3 and at the nitrogen atom of the 3-amino group. Starting compounds bearing a primary amino group in position 3 give 3-(3-acylureido)-2,3-dihydro-1H-indol-2-ones. Starting compounds bearing a secondary amino group in position 3 react according to the character of the other substituent in position 3. If there is a hydrogen atom α to the carbon atom C(3), 4-alkylidene-1′H-spiro[imidazolidine-5,3′-indole]-2,2′-diones arise. If a hydrogen atom is not present in this position, the reaction leads to 3,3a-dihydro-5H-imidazo[4,5-c]quinoline-2,4-diones. Reaction mechanisms for these transformations are proposed. All compounds were characterized by their ¹H, ¹³C, IR and atmospheric pressure chemical ionization mass spectra and some of them also by ¹⁵N NMR data.     

Spectrophotometric determination of mercury(II) with 5,6-diphenyl-2,3-dihydro-asym-triazine-3-thione

A highly selective spectrophotometric method is described for the determination of 0.05–0.55 mg mercury using 5,6-diphenyl-2,3-dihydro-asym-triazine-3-thione (DDTT). The yellow 1:2 complex is extractable into chloroform at pH 10, having a maximum absorbance at 430 nm, ? = 8.1 × 10³M^?1 cm^?1. The only interfering ions are CN^?, Tl(I), and Pd(II). The method was applied to the determination of mercury in organomercury compounds and to the estimation of the solubility product of mercurous sulfate.     

Novel 5,6-bis-(4-substitutedphenyl)-2H(3)-pyridazinones: Synthesis and reactions

A series of 5,6-bis(4-substitutedphenyl)-2H(3)-pyridazinones 2a–f have been synthesized from the condensation of the corresponding benzil monohydrazones 1 either with ethyl cyanoacetate or diethyl malonate in ethanol. The synthesized pyridazinones were converted to the corresponding 3-chloro derivatives 3a–f by the action of phosphoryl chloride. Reaction of the latter halogenated pyridazines with various aromatic amines led to the formation of new 3-aminoaryl pyridazines (4) in moderate yield. The structures of all new compounds 2b,c,e,f, 3b–e, 4 were fully identified by the analysis of their ¹H and ¹³C NMR and mass spectra. Some of these synthetic heterocyclic compounds were screened for their antimicrobial activities but they were almost negative.     

1,5-Diamino-1H-1,2,3,4-tetrazolium picrate: X-ray molecular and crystal structures and ab initio MO calculations

The crystal and molecular structures of 1,5-diamino-1H-1,2,3,4-tetrazolium picrate (DATP) were determined by X-ray diffraction analysis. The tetrazolium cation in DATP has a structure with protonated N4 atom of the ring. Two amino groups in the cation are found to be rather different. The 5-amino group lies in the plane of the tetrazole ring and valence angles around the N atom are close to 120°, which indicates sp² hybridization of atomic orbital of the nitrogen atom. In contrast, valence angles around the N atom of the 1-amino group are close to tetrahedral angle, which suggests sp³ hybridization. The exocyclic C-N bond in the cation is substantially shorter than that in 1,5-diaminotetrazole. The obtained results indicate a conjugation between the π-system of the tetrazole ring and the 5-amino group. The results of ab initio calculations of electronic structure and relative stability for various tautomeric forms of protonated 1,5-diaminotetrazole using MP2/6-31G* and B3LYP/6-31G* levels of theory are in a good agreement with X-ray data and show that there are differences in σ-electron overlap populations for the C-N bonds in the cation in DATP, while π-electrons are delocalized.