Thiazole derivatives represent an important class of azole heterocycles with a broad spectrum of biological activity and, therefore, the synthesis of these compounds is of remarkable concern. We present here practical and reliable protocol for synthesis of some 5-acylthiazoles and demonstrate their utility in the preparation of several new series of thiazole-containing building blocks through transformation of 5-acyl function. Specifically, thiazole-based alcohols, oximes, primary, and secondary amines were successively synthesized in good to excellent yields. The chemical structures of obtained compounds were confirmed by 1H and 13C NMR-spectroscopy, elemental analysis, and mass-spectrometry.

6-Functionalized 7-R-4,7-dihydro[1,2,4]azolo[1,5-a]pyrimidines (R = H or Me) were synthesized by Biginelli-like reaction of formaldehyde or acetaldehyde, aminoazoles, and corresponding beta-dicarbonyl precursor. Alkylation of the obtained compounds proceeds smoothly at position 4, while oxidation leads to 7-R-[1,2,4]azolo[1,5-a]pyrimidines formation. 6-Ethoxycarbonyl derivatives could be reduced to the corresponding alcohols by LiAlH4 and hydrolyzed to the acids. [GRAPHICS] .

The reaction of bromo-substituted chalcones with various diamino-compounds leads to the fused heterocyclic products, aziridinylpiperazines, exhibiting photoreactivity in the crystalline state. Crystals of 4-nitrosubstituted compounds of this family change their color from yellowish to deep violet-blue, 4-cyanosubstituted ones – from yellowish to pink at UV irradiation. Discussion on the mechanism of this phototransformation is still in progress, however, several facts points to the free radial nature of the photogenerated colored semi-products stabilized only by crystalline state of the irradiated samples. Formation of a mixture of positional isomers at interaction of bromo-chalcones with asymmetric diamines of aliphatic/alicyclic or aromatic series at synthesis of the title compounds is of significant interest as well.

6-Unsubstituted 7-R-4,7-dihydro-1,2,4-triazolo[1,5-a]pyrimidines (R = H or Me) were synthesized via two pathways: (a) deacylation of the corresponding 5-acetyl Biginelli-like precursors in KOH/H2O and (b) reduction of the corresponding 1,2,4-triazolo[1,5-a]pyrimidines using LiAlH4. The products could be easily formylated at position 6, which is promising for the further synthesis of functionalized 6-substituted derivatives of 4,7-dihydro-1,2,4-triazolo[1,5-a]pyrimidines. In contrast, 6-acetyl-7-(4-(N,N-dimethylaminopheny1))-5-methyl-4,7-dihydro-1,2,4-triazolo[1,5-a]pyrimidine undergoes a cascade process in KOH/H2O, leading to the formation of a 4,5,8,9-tetrahydro[1,2,4]triazolo[5,1-b]quinazoline derivative. (C) 2017 Published by Elsevier Ltd.

Разработан оптимальный метод синтеза солей вицинальных диаминов -несимметричных алкилпроизводных этилендиамина, основанный на превращении карбонильных соединений по реакции Штреккера в геминальные аминонитрилы с последующим их восстановлением в диамины.Оригинальность этой методики заключается в том, что для минимизации побочных процессов проводится защита аминогрупп с помощью БОК

A series of novel aryl derivatives of 2-pyrazoline bearing 2-benzimidazolyl moiety was synthesized via condensation of corresponding chalcones with phenyl hydrazine.Pyrazoles on their background were obtained by the optimized oxidation procedure with manganese dioxide in benzene.Fluorescent characteristics of the title compounds were determined for their solutions in acetonitrile.Quantum-chemical modeling of molecular structure, UV/Vis spectra, electron density redistribution and structural relaxation at electronic excitation resulting in high fluorescence Stokes shifts were conducted as well.

7-ДИГИДРО[1,2,4]ТРИАЗОЛО[1,5-a]ПИРИМИДИНА М.А.Колосов, Е.Г.Швец, В.Д

The Biginelli-type reactions of 5-amino-3-arylpyrazole-4-carbonitriles with aldehydes and 1,3-dicarbonyl compounds were studied in details. New pyrazolopyrimidines and pyrazoloquinazolines were synthesized through the reaction of 5-amino-3-arylpyrazole-4-carbonitriles with aromatic aldehydes and active 1,3-dicarbonyls (acetyl acetone, acetoacetanilides or cyclohexanedione) in the boiling DMF. The reaction requires no catalysts.

New pyrazolopyrimidines and pyrazoloquinazolines were synthesized through the uncatalyzed reaction of 5-amino-3-arylpyrazole-4-carbonitriles with aldehydes and 1,3-dicarbonyl compounds.

Benzodiazepines are used as anxiolytic, hypnotic, sedative, and antidepressant drugs and to treat anxiety, insomnia, and epileptic seizures and show other types of biological activities. In this study, ten new 4(2)-(8-hydroxyquinolinil-5)-2(-4)-aryl-2,3-dihydro-1H-1,5-benzodiazepines and their rearrangement products, 2-substituted benzimidazoles, were synthesized from 1-aryl-3- (8-hydroxyquinolinil-5) propenone-1 (-3) and ophenylenediamine in methanol-triethylamine (1:1) solution. The reaction between the diamine and chalcones containing the 8-hydroxyquinoline fragment was carried out under mild conditions by base-catalysis amination of the β-enonic fragment of the chalcones followed by cyclo condensation. The structures of these compounds were studied by spectroscopic methods (IR and 1H-NMR) and their chelating properties were demonstrated. We calculated and discuss their theoretical biological activity and the influence of metal chelation on the electron acceptor hydroxyquinolinic fragment on the electronic spectra.

ЭЛЕКТРОННАЯ АБСОРБЦИОННАЯ СПЕКТРОСКОПИЯ БЕНЗИМИДАЗОЛЬНЫХ АНАЛОГОВ ХАЛКОНА В.Н.Котляр, В.Д.Орлов, А

Abstractvia three‐component condensation of 1‐(1‐piperidinylsulfonyl)acetones, aromatic aldehydes, and 3‐amino‐1,2,3‐triazoles

1,3,5-triaryl-2-pyrazolines are organic luminophores with arylic radicals that show a wide biological activity and are used as liquid scintillators and electro-optic materials. Experimental. Eleven 2-pyrazolines were synthesized from phenylhidrazine and chalcones of the 8-hydroxyquinoline series: 3-(8-hydroxyquinolin-5-yl)-1-(3-R)-phenylprop-2-enone and 1-(8-hydroxyquinolin-5-yl)-3--(3-R)-phenylprop-2-enone, where R = H, CH3, OCH3, N(CH3)2, Cl, Br, and NO2. The structures were confirmed by elemental analysis, IR, 1H-NMR, and electronic spectroscopy. Results and discussion. The 1- and 3-aryl substituents of the pyrazoline ring produced shifts to shorter or longer wavelengths, in absorbance and fluorescence. The electron acceptor hydroxyquinolinic fragment influenced the absorption and luminescence spectra; the possible cause of low quantum yields in pyrazolines (1-phenyl-3-(4-R phenyl)-5-(8-hydroxyquinolinil-5)-2-pyrazoline) may be the specific intramolecular fluorescence quenching in bicromophores, characteristic of 5-acceptor substituted pyrazolines, and, in series (1-phenyl-5-(4-R phenyl)-3-(8-hydroxyquinolinil-5)-2-pyrazoline) of excited-state intramolecular proton transfer (ESIPT) reactions, and the increasing donor-acceptor intramolecular interaction of their excited molecules; Density functional calculations (method PM6) were used to probe the electronic structure and energy ordering of the emissive and the electron-transfer states; PM6 results agreed with the experimental data. 1-phenyl-3-(4-R phenyl)-5-(8-hydroxyquinolinil-5)-2-pyrazoline showed fungistatic and fungicide activities. Additionally, all our pyrazolines showed wide theoretical biological activities.

It has been shown that the ternary condensation of oxaloacetic ester (diethyl 2-oxosuccinate), aromatic aldehydes and 3-amino-1,2,4-triazole or 5-aminotetrazole in dimethylformamide results in formation of the corresponding diethyl 7-aryl-4,7-dihydroazolo[1,5-a]pyrimidin-5,6-dicarboxylates. By 1H NMR spectroscopy (according to the data of the chemical shifts of C(2)H-protons for the corresponding N(4)H- and N(4)-methylderivatives of 7-phenyl-4,7-dihydro[1,2,4]triazolo[1,5-a]pyrimidin-5,6-dicarboxylate) it has been found that alkylation of 4,7-dihydro[1,2,4]azolo[1,5-a]pyrimidin-5,6-dicarboxylates in the acetonitrile–saturated water alkali system leads selectively to formation of N(4)-alkyl derivatives. Both the starting compounds obtained and their N(4)-methylsubstituted analogues together with relative diethyl 4-aryl-3,4-dihydropyrimidin-2(1H)-on-5,6-dicarboxylates, 6-unsubstituted 4-aryl-3,4-dihydropyrimidin-2(1H)-on-5-dicarboxylates and the derivatives of 6-COR-7-aryl-4,7-dihydro[1,2,4] triazolo[1,5-a]pyrimidines are the promising objects for studying benzyl C(7)-functionalization of 4,7-dihydroazolo 1,5-a]pyrimidines, as well as of reactions associated with the presence of double C=C-bonds activated by two electron withdrawing groups. Obtaining of the key N(4)H- and N(4)Me-derivatives of 7-phenyl-4,7-dihydro[1,2,4] triazolo- and tetrazolo[1,5-a]pyrimidin-5,6-dicarboxylates also opens the way to the research of biological properties of the compounds of this class. It is noteworthy that being a three-component one the reaction studied, without any doubts, are appropriate for the synthesis of the derivatives of 7-aryl-4,7-dihydro[1,2,4]triazolo- and tetrazolo[1,5-a]pyrimidines containing two electron withdrawing substituents in positions 5 and 6.

Alkylation of 6-C(O)R-7-aryl-5-methyl-4,7-dihydro[1,2,4]triazolo[1,5-a]pyrimidines with methyl iodide or ethyl bromide in either saturated aqueous KОН–MeCN or NaH–DMF led to the formation of N4-alkyl derivatives in good yields (60–98%). Reactivity of the acetyl group of N4-alkyl derivatives towards aromatic aldehydes under the conditions of the Claisen–Schmidt reaction was significantly higher than in 4-unsubstituted compounds. The starting 6-C(O)R-7-aryl-5-methyl-4,7-dihydro[1,2,4]triazolo[1,5-a]pyrimidines were synthesized via a three-component condensation of an aromatic aldehyde, 3-amino-1,2,4-triazole, and a dicarbonyl compound (2,4-pentanedione or ethyl acetoacetate) in DMF.

A three-component condensation of 1-(1-piperidinylsulfonyl) acetones, aromatic aldehydes, and 3-amino-1,2,4-triazole in DMF leads to the formation of 5-alkyl-6-(1-piperidinylsulfonyl)-4,7-dihydro[1,2,4]triazolo[1,5-a]pyrimidine derivatives. If 4-nitrobenzaldehyde is employed, 5-methyl-7-(4-nitrophenyl)[1,2,4]triazolo[1,5-a]pyrimidine is the single isolated reaction product. The starting 1-(1-piperidinylsulfonyl) acetones were obtained from 1-(methylsulfonyl) piperidine in sequential metalation with n-butyllithium, reaction with aliphatic aldehydes, and oxidation of the obtained sulfoalcohols.

The ternary condensation of N-methoxyurea, aldehydes, and 1,3-dicarbonyl compounds, resulting in novel 1-methoxy-3,4-dihydropyrimidin-2(1H)-ones has been examined. Commonly used reaction conditions and catalysts (EtOH/HCl, HOAc, DMF) proved to be unsuitable and we found that the DMF–TMSCl system was the best catalyst. Similarly, the reaction of ureas with 4-chlorobenzaldehyde and 1,3-cyclohexanedione using the DMF/TMSCl system afforded 3,4,7,8-tetrahydroquinazolin-2,5(1H,6H)-diones, while other catalyst systems resulted in the formation of product mixtures. In addition, we have developed an effective and simple protocol for the synthesis of N-(methoxy)urea.

AbstractIn DMSO solution, derivatives (III) exist in equilibrium of two tautomeric forms in various ratios depending on the nature of aryl substituents in chalcone building blocks.

We have demonstrated the preparation of diethyl 6-aryl-2-oxo-1,2,3,6-tetrahydropyrimidine-4,5-dicarboxylates by reaction of urea, oxalacetic ester, and aromatic aldehydes with substituents of various electronic properties. Alkylation of the obtained compounds in the alkyl halogenide–KOH/Н 2 О–MeCN system resulted in mixtures of N -alkyl derivatives, which can be separated by column chromatography. Longer reaction time led selectively to 1,3-dialkylation products.

AbstractA variety of the title pyrimidinedicarboxylates (IV) are synthesized by a Biginelli‐type three‐component reaction and selectively transformed into corresponding 1,3‐dialkylation products [cf.