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141.
The reactions of 3-tert-butyl-7-R1-8-R2-pyrazolo[5,1-c][1,2,4]triazines (R1 = H, Br; R2 = Me, n-Bu) with N-bromosuccinimide in the presence of R3CO2H (R3 = Me, t-Bu, Ph) afforded novel diastereomerically pure 3-tert-butyl-7-R1-8-R2-3,4-dihydropyrazolo[5,1-c][1,2,4]triazine-3,4-diyl dicarboxylates. The structures of the isolated products were established on the basis of IR, 1H, 13C, 2D NOESY NMR, high resolution mass spectrometry and X-ray single-crystal analysis. The steric and mechanistic origins of the observed regio- and stereoselectivity were also discussed. 相似文献
142.
Sergey I. Lopatin Sergey M. Shugurov Andrej I. Panin 《Journal of mass spectrometry : JMS》2019,54(6):507-519
Gaseous CePO2 has been identified by Knudsen effusion mass spectrometry during vaporization of CeO2 and magnesium diphosphate from tungsten double, two‐temperature effusion cell. Structure and molecular parameters of gaseous cerium phosphate under study were determined using quantum chemical calculations. On the basis of equilibrium constants measured for gas‐phase reaction, standard formation enthalpy of CePO2 was determined to be ?508 ± 41 kJ ? mol?1 at the temperature 298 K. 相似文献
143.
Larisa Kimovna Shubina Gunhild von Amsberg Vladimir Anatolievich Denisenko Roman Sergeevich Popov Sergey Anatolievich Dyshlovoy 《Natural product research》2019,33(10):1415-1422
A new pentacyclic guanidine alkaloid, monanchoxymycalin C (1) was isolated from a new collection of marine sponge Monanchora pulchra along with the known monanchoxymycalin A (2). The structure of 1 was elucidated on the basis of spectroscopic data. Monanchoxymycalin C exhibits cytotoxic activity against human cancer HeLa cells at low micromolar concentrations, induces apoptosis-related death of malignant cells and inhibits cancer cell colony formation. In addition, synergistic and additive effects have been observed in combination with cisplatin. 相似文献
144.
Sergey N. Adamovich 《应用有机金属化学》2019,33(7)
This review article summarizes the data on the synthesis, physicochemical properties, structure, reactivity and actual or potential pharmacological activity novel atranes and their analogs synthesized based on biogenic 2‐hydroxyethylamines (and other amines containing the NCH2CH2OH structural unit), biologically active (het)arylchalcogenylacetic acids, and essential metals. 相似文献
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Annemarie Marckwordt Fatima ElOuahabi Hadis Amani Sergey Tin Narayana V. Kalevaru Paul C. J. Kamer Sebastian Wohlrab Johannes G. deVries 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(11):3524-3528
Use of ZrO2/SiO2 as a solid acid catalyst in the ring‐opening of biobased γ‐valerolactone with methanol in the gas phase leads to mixtures of methyl 2‐, 3‐, and 4‐pentenoate (MP) in over 95 % selectivity, containing a surprising 81 % of M4P. This process allows the application of a selective hydroformylation to this mixture to convert M4P into methyl 5‐formyl‐valerate (M5FV) with 90 % selectivity. The other isomers remain unreacted. Reductive amination of M5FV and ring‐closure to ?‐caprolactam in excellent yield had been reported before. The remaining mixture of 2‐ and 3‐MP was subjected to an isomerising methoxycarbonylation to dimethyl adipate in 91 % yield. 相似文献
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149.
Sergey Vyazovkin Alice Mititelu Nicolas Sbirrazzuoli 《Macromolecular rapid communications》2003,24(18):1060-1065
The curing of a mesomorphic epoxy has been studied by polarized light microscopy (PLM) and differential scanning calorimetry. PLM in combination with wide‐angle X‐ray diffraction proves the formation of a liquid crystalline (LC) structure. An advanced isoconversional method reveals that the formation of the LC structure is accompanied by a dramatic decrease in the effective activation from ∼60 to ∼10 kJ · mol−1. A kinetic model of the phenomenon has been discussed.
150.
Riadh Neffati Alexander Alexeev Sergey Saunin Jos C. M. Brokken‐Zijp Daan Wouters Stefan Schmatloch Ulrich S. Schubert Joachim Loos 《Macromolecular rapid communications》2003,24(1):113-117
A systematic investigation into the surface properties of siloxane rubber/carbon black (CB) nanocomposites has been performed, using an automated scanning probe microscope. In this way the influence of CB concentration and curing rate of the siloxane rubber matrix on roughness and conductivity of the composites was studied. Decreasing the curing rate while keeping the CB concentration resulted in a decrease in both roughness and surface conductivity, which can be explained by an additional siloxane‐rubber layer formed during curing.