Aromatic Proton Signals Research Articles

RP-HPLC Separation and 1H NMR Identification of a Yellow Fluorescent Compound-Riboflavin (Vitamin B2)-Produced by the Yeast Hyphopichia wangnamkhiaoensis.

The yeast Hyphopichia wangnamkhiaoensis excretes a brilliant yellow fluorescent compound into its growth culture. In this study, we isolated and identified this compound using reverse-phase high-performance liquid chromatography-diode array detector (RP-HPLC-DAD) as well as 1H NMR and UV-Vis spectroscopy. Two of the three RP-HPLC-DAD methods used successfully separated the fluorescent compound and involved (1) a double separation step with isocratic flow elution, first on a C18 column and later on a cyano column, and (2) a separation with a linear gradient elution on a phenyl column. The wavelengths of maximum absorption of the fluorescent compound-containing HPLC fractions (~224, 268, 372, and 446 nm) are in good agreement with those exhibited by flavins. The 1H NMR spectra revealed methyl (δ 2.30 and 2.40) and aromatic proton (δ 7.79 and 7.77) signals of riboflavin. The 1H NMR spectra of the samples spiked with riboflavin confirmed that the brilliant yellow fluorescent compound is riboflavin. The maximum excitation and emission wavelengths of the fluorescent compound were 448 and 528 nm, respectively, which are identical to those of riboflavin.

Синтез 5-фенил-(5,6-дифенил-)-2,3-дигидро-1,2,4-триазин-3-тионов и исследование их реакций с 1,2-дибромэтаном

5-Phenyl-(5,6-diphenyl-)-1,2,4-triazine-3(2H)-thions (1,2) were synthesized by condensation of phenylglyoxal monohydrate with thiosemicarbazide and benzyl with thiosemicarbazide hydrochloride, respectively. Phenylglyoxal monohydrate was obtained by oxidation of acetophenone with selenous acid by the Riley reaction, while benzyl (1,2-diphenylethane-1,2-dione) waw obtained by oxidation of (2-hydroxy-1,2-diphenylethanone) benzoin with nitric acid by the known procedure. The compounds 1 and 2 were studied in reactions with 1,2-dibromoethane in various ratios. The interaction of triazinethione 1 with 1,2-dibromoethane in molar ratios of 1:1 and 1:2 led to the formation of a previously unknown 3-[(2-bromoethyl)sulfanyl]-5-phenyl-1,2,4-triazine (3а). Using a double excess of 1,2-dibromoethane increased the yield of compound 3а by 11 %. The interaction of triazinethione 2 with 1,2-dibromoethane in molar ratios 1:1 and 2:1 led to the formation of 3-[(2-bromoethyl)sulfanyl]-5,6-diphenyl-1,2,4-triazine (3b). In the 1H NMR spectra of compounds 3a,b there are signals of aromatic ring protons in the region of 7.23-8.81 ppm, a triplet of protons of the SCH2 group at 3.22 and 4.06 ppm, and a triplet of protons of the CH2Br group at 4.39 and 5.28 ppm. It is of interest that1,2-bis-(5-phenyl-[1,2,4]triazinyl-3-sulfanyl)-ethane is formed in the case of the reaction of compound 1 with 1,2-dibromoethane in the 2:1 ratio of reagents. In the 1H NMR spectra of the latter, in contrast to the spectrum of compound 3a, there is a signal of the S-CH2 group protons, which are equivalent in this structure and form a singlet at 3.79 ppm. Compound 3a was also studied by chromatography-mass spectrometry (direct sample insertion). It should be noted that under the conditions of mass spectrum imaging, the bromine atom is split off and the mass spectrum shows a peak with m/z 216 with an intensity of 38% and no peak of the molecular ion. The peak with the maximum intensity (m/z 116, 100 %) seems to correspond to 4-thia-6,7-diaza-1-azoniumbicyclo[3.2.0]hept-1(5)-ene. Its high intensity is due to the fact that the structure of the 1,2-dihydrotriazetium cation is aromatic.

L-Tryptophan Induces a Marine-Derived Fusarium sp. to Produce Indole Alkaloids with Activity against the Zika Virus.

The effects of l-tryptophan supplementation on secondary metabolite production in the marine-derived fungus Fusarium sp. L1 were investigated by culturing the fungus in GPY medium with and without the amino acid. HPLC analysis of the products showed distinct metabolite profiles between the two cultures. The 1H NMR spectrum of the EtOAc extract of the culture supplemented with l-tryptophan displayed a series of characteristic aromatic proton signals (δH 6.50-8.50) and NH signals (δH 10.50-11.50) that were not observed in those from cultures not supplemented with l-tryptophan. Subsequently, 23 distinct indole alkaloids, including six new compounds, fusaindoterpenes A and B (1 and 2), fusariumindoles A-C (3-5), and (±)-isoalternatine A (6), together with 17 known compounds, were obtained from this culture. Fusaindoterpene A (1) contains a 6/9/6/6/5 heterocyclic system. Their chemical structures were determined by analysis of HRMS, NMR spectroscopy, optical rotation calculation, ECD calculation, and single-crystal X-ray diffraction data. Compounds 2, 9, and 15 displayed inhibitory activity against the Zika virus (ZIKV) in a standard plaque assay with EC50 values of 7.5, 4.2, and 5.0 μM, respectively, while not showing significant cell cytotoxicity against the A549 adenocarcinomic human alveolar basal epithelial cell line.

Синтез 5-арил-3-гидрокси-1-(2-гидроксипропил)-4-(фурил-2-карбонил)-3-пирролин-2-онов и 5-арил-3-гидрокси-1-(3-гидроксипропил)-4-(фурил-2-карбонил)-3-пирролин-2-онов

In this work, pyrrolidin-2-ones and their derivatives are considered as a promising class of non-aromatic heterocyclic compounds. Their structure is found in the nuclei of many natural products and biologically active molecules. In pharmacy the possibility of introducing various substituents into the nucleus of pyrrolidin-2-ones is a great importance for the synthesis of new medicinal molecules with improved biological activity. Nowadays the synthesis of new active compounds by introducing various substituents at the C1-, C4- and C5-position of 3-hydroxy-3-pyrrolin-2-one has been little studied and it is of great interest to study the conditions of their synthesis, chemical properties and biological activity. In this research work the corresponding 5-aryl-3-hydroxy-1-(2-hydroxypropyl)-4-(furyl-2-carbonyl)-3-pyrrolin-2-ones and 5-aryl-3-hydroxy-1-(3-hydroxypropyl)-4-(furyl-2-carbonyl)-3-pyrrolin-2-ones were synthesized by the reaction of methyl ester of furyl-2-carbonylpyruvic acid with a mixture of aromatic aldehyde and 1-amino-2-hydroxypropane or 3-amino 1-hydroxypropane when heated in dioxane. The results of the study of the structure of the new synthesized compounds are presented. The structure was proved using 1H NMR spectroscopy and IR spectrometry. It was shown that the IR spectra of the compounds contain bands of the corresponding stretching vibrations of the alcoholic hydroxyl group, enol hydroxyl, amide and ketone groups. In the 1H NMR spectra of the compounds, along with the signals of aromatic protons in the C5 substituent and related groups, characteristic peaks are observed, indicating the formation of the corresponding derivatives of 3-hydroxy-3-pyrrolin-2-ones. It was noted that in the case of the synthesis of 5-aryl-3-hydroxy-1-(2-hydroxypropyl)-4-(furyl-2-carbonyl)-3-pyrrolin-2-ones, the signal of the methine proton at the C5 position of the heterocycle is cleaved in 1H NMR spectra compounds as a result of the appearance of a second chiral center in the 2-hydroxypropyl radical. Elemental analysis was performed for the synthesized compounds.

Structural, Thermal, Morphological, Adsorption and Catalytic Properties of Poly(BPDAH-co-ODA/PPDA)-Ag/V2O5 Nanocomposites

Thermally stable polyimides (PIs) were prepared by condensation technique at 160 ºC for 5 hours in N-methylpyrrolidone (NMP) medium under N2 atmosphere both in the presence and absence of metal (Ag) and metaloxide (MO) (V2O5) nanoparticles (NPs). The synthesized polymers are characterized by Fourier Transform Infra Red (FT-IR) spectroscopy, 1H Nuclear Magnetic Resonance (1H NMR) spectroscopy, Differential Scanning Calorimetry (DSC), Thermal Gravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Field Emission Scanning Electron Microscopy with Energy Dispersive X-Ray (FE-SEM and EDX). The FT-IR spectrum showed a peak at 1786 cm-1 corresponding to the C=O stretching of dianhydride. The aromatic proton signals appeared between 6.7 and 7.5 ppm in the 1H-NMR spectrum of the resultant PIs. The oxydianiline (ODA) based PI with Ag NP loaded system exhibited the highest Tg value. The apparent rate constant values for the adsorption and catalytic reduction of p-nitrophenol (PNP), Cr6+ and rhodamine 6G (R6G) dye were determined with the help of UV-visible spectrophotometer. Among the catalysts, the system loaded with V2O5 NP has higher kapp values. The experimental results are critically analyzed and compared with the previously available literature values. Copyright © 2020 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Planar and sandwich-type Pr(III) and Nd(III) chlorinated phthalocyaninates: Synthesis, thermal stability and optical properties

A direct synthetic approach to four single-decker and one double-decker novel Pr(III) and Nd(III) complexes with 2,3,9,10,16,17,23,24-octachlorophthalocyaninate and 1,2,3,4,8,9,10,11,15,16,17,18,22,23,24,25-hexadecachlorophthalocyaninate has been developed. Synthesis of hexadeca-Cl-substituted Nd(III) bisphthalocyaninate has been carried out utilizing two preformed synthetic blocks: Nd(III) octachlorophthalocyaninate acetate and octachlorophthalocyanine ligand. Due to the electron withdrawing effect of 16 chlorine groups, this Nd(III) bisphthalocyaninate was obtained as a redox stable anionic form. Upfield lanthanide-induced shifts of the aromatic proton signals (up to 2.04 ppm for Pr(III) octachlorophthalocyaninate acetate) were observed in the 1H NMR spectra of the obtained phthalocyaninates. Thermal stability of the lanthanide (III) complexes was examined using thermogravimetric analysis combined with mass-spectrometry. The double-decker compound was shown to possess an increased thermal stability in comparison with the single-deckers up to ~400 °C. Linear and nonlinear optical properties of the Cl-substituted Nd(III) and Pr(III) phthalocyaninates have been investigated using z-scan technique. The best nonlinear optical response with the highest excited state absorption cross-section (σ1 = 1.1 × 10−15 cm−2) was found for the hexadeca-Cl-substituted Nd(III) monophthalocyaninate.

Phenyl-substituted terbium(III) single- and multiple-decker phthalocyaninates: Synthesis, physicochemical properties and peculiarities of self-assembly in solid phase

Selective synthetic approaches to novel single- and multiple-decker terbium(III) phthalocyaninates, bearing peripheral phenyl groups, were developed. The compounds were identified by nuclear magnetic resonance spectroscopy, high resolution mass spectrometry, Fourier-transform infrared and UV–Vis spectroscopy. From the X-ray data for initial 1,2-dicyano-4,5-diphenylbenzene it was shown that phenyl groups are not in the same plane, and dihedral angle between them equals 64°. Strong upfield shifts of the aromatic proton signals up to −131.62 ppm in the case of a triple-decker complex were found in the nuclear magnetic resonance spectra due to paramagnetic nature of terbium(III) ion. Stronger intramolecular interactions are observed for the sandwich-type phenyl-substituted terbium complexes comparing to tert-butyl-substituted analogs, earlier described in literature. In the case of the double-decker compound, this results in 142 nm hypsochromic shift of the intervalence absorption band. DC conductivity measurements were carried out for terbium(III) phthalocyaninates. The formation of the ring-shaped self-assembled aggregates with a diameter of 400 nm was observed in thin solid films of the prepared terbium(III) compounds by atomic force microscopy.

TELLUROCYCLISATION OF CONDENSED N-ALKENYL DERIVATIVE 4-OXOPYRYMIDINE-2-TION

The derivatives of quinazolines and their fused analogues are promising objects for the rational design of biologically active compounds as prototypes for innovative medicines. This is due to the fact that the quinazoline fragment is a structural unit of many natural alkaloids. Electrophilic intramolecular heterocyclization is a promising method for the synthesis of fused derivatives of quinazoline.This research is devoted to the synthesis of new functionalized unsaturated condensed derivatives of quinazolin-4-one and the study of the regio chemistry of the process of electrophilic heterocyclization under the action of tellurium tetrachloride. The choice of such an electrophilic reagent is due to the fact that in recent years the organic synthesis of chalcogen-containing compounds, in particular, tellurium compounds that exhibit a wide range of biological activity, is increasingly developing.It was established that the electrophilic intramolecular cyclization of 3-alkenyl-2-thioquinazolin-4-one under the action of tellurium tetrachloride in an aqueous acetic acid medium at room temperature takes place with the participation of the alkenyl moiety and the exocyclic sulfur atom in the second position of quinazoline. As a result, thiazolidinequinazoline systems of linear structure were obtained. The structure and composition of the obtained tellurium-containing hydrochlorides has been proved by 1H, 13C NMR spectra and elemental analysis. In the PMR spectrum of hydrochlorides, signals of aliphatic cyclic methylene and methine groups and of the acyclic trichlorotellanylmethyl group are observed, which, together with the signals of aromatic protons, indicates on the formation of thiazolidinequinazolones. The absence of signals characteristic of the C=S group and presence of signals typical for the C-S bond in the 13C NMR spectra are in accord with the proposed structure of the cyclization products.Thus, we investigated the regio chemistry of the electrophilic intramolecular cyclization of 3-alkenyl-2-thioquinazolin-4-one under the action of tellurium tetrachloride. It was proved that the annelation of the thiazolidine cycle takes place with the participation of the sulfur atom in the second position of the pyrimidine, with the formation of tricyclic hydrochlorides of linear structure.

Lanthanide (III) complexes of 3-(ethylthio)phenyl-substituted phthalocyanines: Synthesis and physicochemical properties

Novel phthalocyaninates of terbium, erbium and lutetium, bearing 3-(ethylthio)phenyl peripheral groups, were synthesised with high yields. The complexes obtained were characterised by 1H nuclear magnetic resonance spectroscopy, Fourier-transform infrared spectroscopy and high-resolution mass spectrometry. Thermal stability of the lanthanide complexes was examined using thermogravimetric analysis combined with fourier-transform infrared spectroscopy. Strong upfield (up to −59.06) and downfield (up to 22.32) lanthanide-induced shifts of signals of aromatic protons were observed in nuclear magnetic resonance spectra of terbium and erbium complexes respectively. It was shown, that comparing to phenyl-substituted analogues the introduction of ethylthio-moieties in the meta-positions of phenyl substituents does not affect the Q band maxima. Hybrid gold nanoparticles coated with molecules of the lutetium complex were obtained and their optical properties were studied. The formation of phthalocyanine shell and its composition were proven using atomic force and transmission electron microscopy. Absorption cross-sections of ground and the first excited states were calculated using the data of open-aperture z-scan measurements for lutetium complex and hybrid gold nanoparticles on its basis.

Physical-chemical properties of 5-(3-fluorophenyl)-4-amino-1,2,4-triazole-3-thiol s-derivatives

Introduction. Currently an attempt to combine 1,2,4-triazole heterocycle with various pharmacologically active fragments of other organic molecules is popular among the scientists. Earlier we have noted that the introduction of fluorophenyl radical in the 1,2,4-triazole structure leads to the formation of compounds with new properties and it stimulates and inspires scientists for further search of new compounds among 1,2,4-triazole-3-thiol fluorphenylderivatives.The aim of our study was to synthesize new derivatives of S-5-(3-fluorophenyl)-4-amino-1,2,4-triazole-3-thiol, to explore the physical and chemical properties for the first time obtained 3-(3-fluorophenyl)-6-(aryl-, heteryl)-[1,2,4]triazole[3,4-b][1,3,4] thiadiazole.Research materials and methods. The study of the physical and chemical properties of 5-(3-ftorfenyl)-4-amino-1,2,4-triazole-3-thiol and 3-(3-ftorfenyl)-6-(aryl-, heteryl)-[1,2,4]triazole[3,4-b][1,3,4]thiadiazoles has been conducted using certified and licensed equipment of physical and chemical laboratories in Zaporozhye State Medical University according to the plans of the study.Research results. The structure of the synthesized 3-(3-ftorfenyl)-6-(aryl-, heteryl)-[1,2,4]triazole[3,4-b][1,3,4]thiadiazoles has been proved using modern physical-chemical methods of analysis (elemental analysis, 1H NMR spectroscopy, chromatography-mass spectrometry), and their identity has been confirmed chromatographically. The signals of aromatic protons 3-(3-ftorfenyl)-6-(aryl-, heteryl)-[1,2,4]triazole[3,4-b][1,3,4]thiadiazoles in the 1H NMR-spectrum registered as doublets, triplets, multipletes and relevant chemical shifts. Analyzing the constants peaks of pseudomolecular ions of initial compound and corresponding 3-(3-ftorfenyl)-6-(aryl-, heteryl)-[1,2,4]triazole[3,4-b][1,3,4]thiadiazoles we can assert about the compliance between the calculated values of the mass and found mass in the analysis.Conclusions. Using the known methods of synthesis we have obtained for the first time the 5-(3-fluorophenyl)-4-amino-1,2,4-triazole-3-thiol which was cyclized in the presence of the relevant aryl-, heterylacetic acids in POCl3. We have obtained a whole series of new 3-(3-ftorfenyl)-6-(aryl-, heteryl)-[1,2,4]triazole[3,4-b][1,3,4]thiadiazoles. The reaction of cyclization and confirmation of the obtained molecules’ structure have been proved by modern complex methods of analysis (elemental analysis, 1H NMR-spectroscopy, chromatography-mass spectrometry).

SYNTHESIS OF 2-(3-CHROMENYL)-4-ETHOXYCARBONYL-1-(4-FLUOROBENZYL)-5-METHYLIMIDAZOLE 3-OXIDES

In addition to our search for probable HIV-1 integrase inhibitors in the series of imidazole derivatives a possibility of preparation of 2-(3-chromenyl)substituted imidazole 3-oxides containing fluorobenzyl moiety in position 1 of imidazole ring as a potential pharmacophore was demonstrated. 4-ethoxycarbonyl-1-(4-fluorobenzyl)-5-methyl-2-(4-oxo-4H-chromen-3-yl)imidazole 3-oxide 4a and 4-ethoxycarbonyl-2-(6-hydroxy-4-oxo-4H-chromen-3-yl)-1-(4-fluorobenzyl)-5-methyli-midazole 3-oxide 4b were synthesized starting with fluorobenzylamine 1, ethyl 2-(hydroxyimino)-3-oxobutanoate 2 and 4-oxo-4H-chromen-3-carbaldehyde 3a or 6-hydroxy-4-oxo-4H-chromen-3-carbaldehyde 3b, respectively. The condensation was carried out at room temperature in glacial acetic acid. Two novel imidazole N-oxides were characterized by 1H NMR and IR spectroscopy and mass-spectrometry. It should be noted that in 1H NMR spectra of the discussed imidazole N-oxides (recorded in deuterated DMSO) the singlet of the proton in the position 2 of chromenyl ring is shifted to lower field (8.70 and 8.78, respectively) as compared with the signals of other aromatic protons. Such deshielding is typical for this kind of heterocyclic system and may be explained by the influence of the electron-withdrawing of N-oxide moiety. In the IR spectrum of 4-ethoxycarbonyl-1-(4-fluorobenzyl)-5-methyl-2-(4-oxo-4H-chromen-3-yl)imidazole 3-oxide 4a the absorption bands corresponding to the carbonyl groups appear at 1641 cm-1 (for C=O in the position 4 of chromenyl ring) and 1641 cm-1 (C=O of the ester moiety). In the IR spectrum of 4-ethoxycarbonyl-2-(6-hydroxy-4-oxo-4H-chromen-3-yl)-1-(4-fluorobenzyl)-5-methylimidazole 3-oxide 4b the position of the former band remains practically unchanged (1646 cm-1), whereas the latter band is shifted to higher frequencies (1715 cm-1) due to intermolecular interactions with OH-group in the position 6 of the chromene. The absorption band for this group appears as a broad band with medium intensity and maximum absorption at 3228 cm-1. In the mass spectra of imidazole N-oxides under consideration peaks of the molecular ions (M+) and peaks (M-16) are observed. The demonstrated possibility of the synthesis of the titled compounds allows the further planning of the synthesis of a series of such structures varying the substituents in both chromenyl and imidazole rings. Forcitation:Razgulyaev V.I., Nikitina P.A., Koldaeva T.Yu., Miroshnikov V.S., Perevalov V.P. Synthesisof 2-(3-chromenyl)-4-ethoxycarbo-nyl-1-(4-fluorobenzyl)-5-methylimidazole 3-oxides. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 2. P. 17-19.

Synthesis of Dibromo[3.3]paracyclophanes

All possible pseudogeminal-, pseudoortho-, pseudometa-, and pseudopara-dibromo[3.3]paracyclophanes were synthesized by the (p-tolylsulfonyl)methyl isocyanide (TosMIC) coupling method, and characterized by the aromatic proton signals of the 1H NMR spectra and finally by the X-ray crystal structure analyses of the pseudogeminal, pseudo­ortho, and pseudopara isomers.

Folding-Generated Molecular Tubes Containing One-Dimensional Water Chains.

A series of indolocarbazole-pyridine (IP) oligomers were prepared that fold into helical conformations, and their folding features in solution and in the solid state were revealed. Helical folding of these IP foldamers is induced by dipolar interactions through the ethynyl bond and π-stacking between two repeating units. Upon helical folding, (1)H NMR signals of aromatic protons were significantly shifted upfield by Δδ = 0.5-2.2 ppm. In addition, hypochromic shifts and fluorescence quenching were observed in the absorption and emission spectra. X-ray crystal structures clearly demonstrated that IP foldamers folded to helical structures with cylindrical internal cavities wherein 3 or 5 water molecules were occupied by hydrogen-bonding interactions in a 1-D array, reminiscent of transmembrane water channels, called aquaporins.

The synthesis and analgesic properties of N-(benzyl)-2-hydroxy-9-methyl-4-oxo-4H-pyrido[1,2-a]pyrimidine-3-carboxamides

Continuing the search for new analgesics among derivatives of azahetarylcaboxylic acids by the reaction of ethyl 2-hydroxy-9-methyl-4-oxo-4H-pyrido[1,2-a]pyrimidine-3-carboxylate and benzylamines in boiling ethanol the corresponding group of N-(benzyl)-2-hydroxy-9-methyl-4-oxo-4H-pyrido[1,2-a]pyrimidine-3-carboxamides has been synthesized. The structure of the compounds obtained has been confirmed by the data of elemental analysis and NMR 1H spectroscopy. It is noted that the signals of aromatic protons of pyrido-pyrimidine nuclei are shifted downfield and generally for a typical AMX spin system. At the same time, the signals of aromatic protons of benzilamide fragments on the contrary are shifted upfield in all cases and focused on very narrow segments of the spectra, thereby undergoing strong distortion. According to the results of the primary pharmacological screening it has been found that using the standard model of “acetic acid writhings” all N-(benzyl)-2-hydroxy-9-methyl-4-oxo-4H-pyrido[1,2-a]pyrimidine-3-carboxamides without exception have analgesic properties to a greater or lesser degree. Practically the same regularities of the benzylamide fragment structure –biological effect relationship as in the case of 4-hydroxyquinolin-2-ones analogues have been found. Based on it the conclusion about bioisosterism of 4-hydroxyquinolin-2-one and 2-hydroxy-9-methyl-4-oxo-4H-pyrido[1,2-a]pyrimidine nuclei has been made.

Chemical Constituents of Moringa oleifera and Their Cytotoxicity Against Doxorubicin-Resistant Human Breast Cancer Cell Lines (Mcf-7/Adr)

Moringa oleifera Lam. (Moringaceae), commonly known as the drumstick tree or the horseradish tree, is a shrub and small deciduous tree of 2.5 to 10 m height [1]. The leaves of the titled plant, as well as the flowers, roots, gums, fruits, and seeds, are extensively used for treating cardiovascular disease [2], liver disease [3], cancer [4], and hematologic, hepatic, and renal disease [5]. Compared to extensive medicinal studies, the limited phytochemical investigations report mainly the identification of glycosides and alkaloids such as 4-( -L-rhamnosyloxybenzylglucosinolate), niazimicin, niazirin, and moringine [6–9]. Breast cancer is a disease of humans and other mammals; while the overwhelming majority of cases in humans involve women, men can also develop breast cancer [10, 11]. MCF-7 and two other tumor cell lines account for more than two-thirds of all human breast cancer reported cases. Clinically, the number of doxorubicin-resistant MCF-7 adenocarcinoma (MCF-7/ADR) cases has grown, making traditional chemotherapy fail. In the preliminary trials performed by our group, the low-polarity fraction of the methanol extracts of the root barks of M. oleifera at 50 g/mL concentration displayed significant cytotoxicity against MCF-7/ADR tumor cell lines with an inhibition percentage of 56%. Therefore, in our continuing program aimed at the discovery of new anti-tumor drugs, M. oleifera was selected as the target, and in present study we wish to report the structural elucidation of compounds 1 and 2 and the cytotoxicity of some of these isolates towards the MCF-7/ADR adenocarcinoma cell lines. Air-dried and powdered root barks of M. oleifera were extracted with MeOH under reflux. The methanol extracts were purified using a combination of conventional chromatographic techniques. N-benzylcarbamic acid (1) and 4-( -L-rhamnopyranosyloxy)benzaldehyde (2), along with 25 known compounds, were identified, and comprehensive studies of their spectral and physical data were made. Compound 1 was isolated as a white powder with mp 244–245 C, and the HR-MS analytical data of 1 displayed a pseudomolecular ion peak at m/z 152.0736 corresponding to the molecular formula of C8H9NO2. The UV absorption maxima at 267 and 211 nm were characteristic of the existence of a benzenoid moiety [12]. The IR absorption bands at 3322 and 1621 cm–1 suggested the presence of hydroxyl and amide carbonyl groups, respectively. In the 1H NMR spectrum, a set of mutually coupled aromatic proton signals at 7.25–7.32 (5H, m) and a doublet signal at 4.36 (2H, J = 5.7 Hz, H-1 ) indicated the partial structure of the benzyl moiety. In addition, in the 13C NMR spectrum, the carbon signal at 158.0 (C-3 ) was characteristic of a carbamic acid group in compound 1, and another set of aromatic carbon signals at 139.0 (C-1), 128.7 (C-3, 5), and 127.4 (C-2, 6), 127.4 (C-4) confirmed the presence of a mono-substituted benzene basic structure. Thus, the chemical structure of 1 was established as N-benzylcarbamic acid. Although this compound had already been reported in the previous synthesis work [13], this is the first report from a natural source.

Synthesis, reaction, and optical properties of cyclic oligomers bearing 9,10-diphenylanthracene based on an aromatic tertiary amide unit

Novel cyclic aromatic amide oligomers containing highly fluorescent 9,10-diphenylanthracene units were prepared by condensation of a monomer with amino and ester functional groups using lithium bis(trimethylsilyl)amide. The cyclic trimer (C3A, 40%) and tetramer (C4A, 8%) were isolated using preparative gel permeation chromatography. Some of the aromatic proton signals derived from anthracene were observed in the upfield region (6.96–6.87 ppm) in the 1H nuclear magnetic resonance spectrum of C3A. X-ray crystallographic analysis indicated that three anthracene moieties are inclined with respect to the cyclic skeleton and partly overlap each other. The fluorescence peak maximum of C3A (438 nm) showed a small red-shift compared with that of an acyclic model compound (425 nm). Reduction of the amide carbonyl group in C3A gave the cyclic trimer HC3A, which has a tertiary amine unit. The fluorescence peak maximum of HC3A (489 nm) was largely red-shifted from that of C3A and exhibited strong solvent dependence. A linear correlation was observed between the Stokes shift (Δν), ranging from 2981 to 6646 cm−1, and the Reichardt's solvent polarity parameter [ET(30)].

Hydroxypropyl tannin derivatives from Pinus pinaster (Ait.) bark

Tannins from Pinus pinaster bark were modified with propylene oxide (PO) in aqueous alkali at room temperature (∼22°C) for the first time. The hydroxypropylation to four different degrees of substitution (DS) produced derivatives (HPT) with monosubstituted phenolic functionalities in yields in excess of 80%. The isolated HPTs were characterized by FT-IR, UV–vis, 1H NMR and bidimensional spectroscopies (HMBC, HSQC and COSY). The integration of the aromatic proton signals in the 1H NMR spectra of acetylated HPT allowed for an easy quantitative determination of DS. HPTs possess properties that are expected to enhance their role in new oligomeric building-blocks for the synthesis of engineered plastics and tannin-based bio-foams.

Synthesis of diaryl-substituted 3,4-dimethyl-2-oxo-1,2,3,6-tetrahydropyrimidine-5-carboxamides

In the H NMR spectra of compounds I–V, alongside the signals of aromatic protons and groups attached to the aromatic ring, there are two singlets at 3.05–3.10 and 1.91–2.27 ppm belonging to the CH3 groups, the doublets of СН proton at 5.22–5.64 ppm, and of the NH proton at 7.60–7.96 ppm (J1,6 2.95– 3.33 Hz), the singlet of the amide protons in the range of 9.02–9.43 ppm. The splitting of signals of the H protons of the pyrimidine ring indicates that the DOI: 10.1134/S1070363213040324

A screw-shaped alignment of pyrene using m-calix[3]amide

m-Calix[3]amide bearing three pyrenes (1a) was prepared by the condensation reaction of 3-nonylaminobenzoic acid derivative using Ph3PCl2. Pyrenyl groups were found to be aligned in the screw-like fashion by m-calix[3]amide as confirmed by the X-ray crystallography. Aromatic proton signals observed at the up-field region in the 1H NMR spectrum at low temperature indicated that pyrenyl groups in 1a are aligned in close proximity in THF solution. UV–vis absorption and fluorescence emission spectra did not show marked peak shift nor concentration fluorescence quenching compared with reference compounds implying no significant electronic interaction between pyrenyl groups. These results can be explained by the steric effect of the m-calix[3]amide platform. On the other hand, an excimer emission was observed for m-calix[3]amide having a flexible spacer between pyrene and m-calix[3]amide (1b).

Binding of nitrophenol isomers to calix[n]arene (n = 4, 6) hosts

Electronic structure, 1H NMR and vibrational spectra of complexes between nitrophenol isomer and calix[n]arene (n=4 or 6) are obtained from density functional theory. Nitrophenol interacts laterally with calix[4]arene portals and reveals shielding of all aromatic guest protons in the calculated 1H NMR spectra. The intense OH stretching vibration at the 3287cm−1 of calix[4]arene on complexation splits into two bands separated by ∼30cm−1. On the other hand, CX[6] host favors encapsulation of nitrophenol isomer via hydrogen bonded interactions. Complexation of p-nitrophenol with CX[6] engenders up-field signals for aromatic protons on confining within the host cavity while those of o- or m-nitrophenol isomers exhibit both shielding as well as deshielding thereby leading to distinct 1H NMR signals. Interaction energy of nitrophenol toward CX[6] host follows the order: p-nitrophenol>m-nitrophenol>o-nitrophenol, which is reflected in the frequency downshift of OH stretching (host) from OH···O interactions.