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101.
Maksym S. Kazunin Oleksii Yu. Voskoboynik Inna S. Nosulenko Galina G. Berest Sergiy V. Kholodniak Boris O. Pryymenko Sergiy I. Kovalenko 《Journal of heterocyclic chemistry》2020,57(1):268-280
The synthesis of 6-(2-hydroxy-2-aryl (heteryl)ethyl)-1-methylpteridine-2,4,7(1H,3H,8H)-triones by the reduction of the corresponding ketones and the peculiarities of conversion of the synthesized alcohols to (E)-1-methyl-6-(2-aryl (heteryl)ethenyl)pteridine-2,4,7(1H,3H,8H)-triones was reported. The mechanism of monomolecular elimination that occurred in the presence of hydrogen halides was discussed, namely, the competitive formation of an energy-efficient conjugated system by deprotonation of a stable benzyl-type carbocation. Alternative synthesis methods of pteridine-2,4,7(1H,3H,8H)-triones were developed. Abovementioned approach involved [4+2]-cyclocondensation of 1-methyl-5,6-diaminouracil to 2-oxo-4-R-but-3-enoic acids and Knoevenagel condensation of 1,6-dimethylpteridine-2,4,7(1H,3H,8H)-trione with aromatic aldehydes. The antiradical, antimicrobial, and antifungal activities were studied for the synthesized compounds. 相似文献
102.
Andrienko I. V. Kovalenko E. A. Samsonenko D. G. Fedin V. P. 《Russian Chemical Bulletin》2020,69(11):2113-2120
The crystals of the compounds [Na4(H2O)14CB[6]](bdc)2 · 13H2O (1) and [Na6(H2O)19CB[6]]-(bdc)3 ·15H2O (2) were obtained by heating an aqueous solution of sodium terephthalate (Na2bdc) and cucurbit[6]uril (CB[6]). According to the single-crystal X-ray diffraction data, the sodium aqua complexes and cucurbit[6]uril molecules form chains (in structure 1) and layered metal-organic frameworks (in structure 2). The structures of the sodium aqua complexes [Na3(H2O)10]3+ in 1 and [Na6(H2O)19]3+ in 2 have been previously unknown. When submitted to ultraviolet radiation, crystals of 1 and 2 exhibit luminescence with an emission maximum at 428 and 434 nm, respectively.
相似文献103.
Zhoulong Fan Katherine L. Bay Xiangyang Chen Zhe Zhuang Han Seul Park Kap‐Sun Yeung K. N. Houk Jin‐Quan Yu 《Angewandte Chemie (International ed. in English)》2020,59(12):4770-4777
A simple and efficient nitrile‐directed meta‐C?H olefination, acetoxylation, and iodination of biaryl compounds is reported. Compared to the previous approach of installing a complex U‐shaped template to achieve a molecular U‐turn and assemble the large‐sized cyclophane transition state for the remote C?H activation, a synthetically useful phenyl nitrile functional group could also direct remote meta‐C?H activation. This reaction provides a useful method for the modification of biaryl compounds because the nitrile group can be readily converted to amines, acids, amides, or other heterocycles. Notably, the remote meta‐selectivity of biphenylnitriles could not be expected from previous results with a macrocyclophane nitrile template. DFT computational studies show that a ligand‐containing Pd–Ag heterodimeric transition state (TS) favors the desired remote meta‐selectivity. Control experiments demonstrate the directing effect of the nitrile group and exclude the possibility of non‐directed meta‐C?H activation. Substituted 2‐pyridone ligands were found to be key in assisting the cleavage of the meta‐C?H bond in the concerted metalation–deprotonation (CMD) process. 相似文献
104.
Erling Haskjold WencheMarie Olsen Rolf Bjerkens Katherine Kravik 《Photochemistry and photobiology》1993,57(4):663-666
Abstract— The right eyes of 40 rats were exposed to a signal erythemogenic dose fo ultraviolet B irradiation (UVB) at 297nm. The irradiation was directed perpenddicualr to the center of the cornea. The left eyes served as controls. The animals were randomly assigned into 10 groups. The labelling index (LI) after pluse labeling the tritiated thymidine and the mitotic rate (MR) after Colcemid administration were registered in the corneal epithelium at predetermined intervals up to 96 h after the irradiation. A mathematical method was used to corealted corresponding corneal areas from the different animals. In the central the LI was considerably reduced up to 36h after the irradiation. The LI increased toward the peripheral cornea and reached normal values at the limbal area. The MR was also reduced up to 36h. However, this reduction was over the entire epithelium. The block in cell proliferation was followed by increased proliferation. 相似文献
105.
Kovalenko E. S. Murashev M. M. Stolyarova E. K. Podurets K. M. Glazkov V. P. Presnyakova N. N. Borisova P. A. Svetogorov R. D. Gogin A. A. Greshnikov E. A. Zaytseva I. E. Yatsishina E. B. 《Crystallography Reports》2020,65(6):1073-1080
Crystallography Reports - A medieval Russian bronze pendant icon with enamel images, dated to the period from the 12th to the first half of the 13th century was studied. The investigation was... 相似文献
106.
Vadim A. Dubskikh Anna A. Lysova Denis G. Samsonenko Alexander N. Lavrov Konstantin A. Kovalenko Danil N. Dybtsev Vladimir P. Fedin 《Molecules (Basel, Switzerland)》2021,26(5)
Three new 3D metal-organic porous frameworks based on Co(II) and 2,2′-bithiophen-5,5′-dicarboxylate (btdc2−) [Co3(btdc)3(bpy)2]·4DMF, 1; [Co3(btdc)3(pz)(dmf)2]·4DMF·1.5H2O, 2; [Co3(btdc)3(dmf)4]∙2DMF∙2H2O, 3 (bpy = 2,2′-bipyridyl, pz = pyrazine, dmf = N,N-dimethylformamide) were synthesized and structurally characterized. All compounds share the same trinuclear carboxylate building units {Co3(RCOO)6}, connected either by btdc2– ligands (1, 3) or by both btdc2– and pz bridging ligands (2). The permanent porosity of 1 was confirmed by N2, O2, CO, CO2, CH4 adsorption measurements at various temperatures (77 K, 273 K, 298 K), resulted in BET surface area 667 m2⋅g−1 and promising gas separation performance with selectivity factors up to 35.7 for CO2/N2, 45.4 for CO2/O2, 20.8 for CO2/CO, and 4.8 for CO2/CH4. The molar magnetic susceptibilities χp(T) were measured for 1 and 2 in the temperature range 1.77–330 K at magnetic fields up to 10 kOe. The room-temperature values of the effective magnetic moments for compounds 1 and 2 are μeff (300 K) ≈ 4.93 μB. The obtained results confirm the mainly paramagnetic nature of both compounds with some antiferromagnetic interactions at low-temperatures T < 20 K in 2 between the Co(II) cations separated by short pz linkers. Similar conclusions were also derived from the field-depending magnetization data of 1 and 2. 相似文献
107.
Inside Back Cover: Photocatalytic Formic Acid Conversion on CdS Nanocrystals with Controllable Selectivity for H2 or CO (Angew. Chem. Int. Ed. 33/2015)
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108.
Steven J. Langford Marcia A.-P. Lee Katherine J. Macfarlane Josephine A. Weigold 《Journal of inclusion phenomena and macrocyclic chemistry》2001,41(1-4):135-139
A series of complexes of the type [Sn(TTP)L2] have been prepared by the condensation of [Sn(TTP)OH2] (TTP = meso-tetratolylporphyrin) with a range of substituted phenols. The resulting complexes were characterised using 1H NMR and single crystal X-ray diffraction techniques. In each case, the condensation of the phenols with the Sn(IV)porphyrin in CDCl3 solution is slow (h) but essentially quantitative. The slow kinetics of the formation of the diaxial phenolate complexes allows for the identification, by 1H NMR spectroscopy, of three independent complexes within this process, namely an outer-sphere (H-bonded) complex as well as two independent phenolate complexes. The rate of condensation is in the order phenol 4-methoxyphenol > 4-nitrophenol and suggests a steric rather than pKa dependency. 相似文献
109.
I. F. Makarevich S. N. Kovalenko T. D. Gusarova Yu. I. Gubin 《Chemistry of Natural Compounds》2009,45(1):40-44
Twelve compounds including secologanin, loganin, the aglycon of loganin, and a new iridoid called glucologanin were isolated
from fruit of common snowberry Symphoricarpos albus (L.) Blake. The structure of glucologanin was confirmed using PMR and mass spectroscopy and chemical transformations. 2′,3′,4′,6′,7-Penta-O-acetylloganin and 2′,3′,4′,6′-tetra-O-acetylloganin were synthesized.
Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 37–40, January–February, 2009. 相似文献
110.