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RSC Adv., 2017, 7, 10070-10073

A.S. Smirnov, D.N. Nikolaev, V.V. Gurzhiy, S.N. Smirnov, V.S. Suslonov, A.V. Garabadzhiu, P.B. Davidovich

“Conformational stabilization of isatin Schiff bases – biologically active chemical probes”

RSC Adv., 2017, 7, 10070-10073
DOI: 10.1039/c6ra26779c
source: http://pubs.rsc.org/en/Content/ArticleLanding/2017/RA/C6RA26779C#!divAbstract

Isatin Schiff base derivatives have a wide range of biological effects. Unfortunately, these compounds possess a serious topological shortcoming: the conformational E ⇆ Z interconversion. Two ways of conformation stabilization are reported here: complexation with metals that stabilize the E-conformer and substitution in the 4th position of the isatin core stabilizing the Z-form.

Eur. J. Org. Chem., 2017, 2587-2595

A. Stukalov, V.V. Sokolov, V.V. Suslonov, M.A. Kuznetsov

“Pyrazoles and C-Imidoylaziridines through [4+1] Annulation and [2+1] Cycloaddition of 1-Azabuta-1,3-dienes with a Synthetic Equivalent of Phthalimidonitrene”

Eur. J. Org. Chem., 2017, 2587-2595
DOI: 10.1002/ejoc.201700172

Oxidative addition of N-aminophthalimide to 1,2,4-triaryl-1-azabuta-1,3-dienes leads, in most cases, to the regiodefined formation of 1,3,5-triarylpyrazoles in moderate to good yields through [4+1] annulation. This transformation is supposed to proceed by nitrenoid attack onto a lone pair of electrons of the imine nitrogen atom to give the vinylazomethine imine, followed by its 1,5-electrocyclization into pyrazoline and further aromatization into pyrazole. Rare examples of 2-imidoyl-1-phthalimidoaziridines that are formed by competitive [2+1] cycloaddition onto the C=C bond were isolated in low yields for 1-azadienes with electron-deficient aryl substituents at the imine nitrogen atom.

Brochure 2017

One can find review of CMR in our brochure

Excursion


Mikhail Vovk has presented an excursion-lecture about modern NMR spectroscopy methods for high school students. The equipments presented in CMR and some aspect of its application were demonstrated during the excursion.

Tetrahedron Lett., 2017, 58, 172-174

M.A. Kuznetsov, A.N. Shestakov, M. Zibinsky, M. Krasavin, C.T. Supuran, S. Kalinin, Muhammet Tanç

“Synthesis, structure and properties of N-aminosaccharin – A selective inhibitor of human carbonic anhydrase I”

Tetrahedron Lett., 2017, 58, 172-174
DOI:10.1016/j.tetlet.2016.12.005

Previously unknown N-aminosaccharin was prepared in good yield via the one-step direct amination of saccharin sodium salt with hydroxylamine-O-mesitylenesulfonic acid (MSH) and its reactivity investigated. N-aminosaccharin and its derivatives were tested against hCA isoforms and the parent compound was identified to be a selective, low micromolar inhibitor (Ki = 8.8 μM) of hCA I. These findings provide a ligand-efficient starting point for the design of potent hCA I inhibitors – a promising drug target for retinal/cerebral edema treatment.

 

Tetrahedron, 2017, 73, 3939-3948

A.N. Shestakov, A.S. Pankova, P.Golubev, A.F. Khlebnikov, M.A. Kuznetsov

“Brønsted acid mediated cyclizations of ortho-aryl(ethynyl)pyrimidines”

Tetrahedron, 2017, 73, 3939-3948
DOI:10.1016/j.tet.2017.05.070

A high-yielding procedure for the synthesis of 5-aryl-4-(arylethynyl)pyrimidines from easily available 2-aryl-3-hydroxyacrylates is reported. These pyrimidines readily undergo cyclization in strong Brønsted acids and, depending on the substitution in alkynylpyrimidines and the water content of the reaction mixture, yield either benzo[f]quinazolines or derivatives of spiro[cyclohexa-2,5-diene-1,5′-cyclopenta[d]pyrimidin]-4-one. In most cases the cyclization proceeds nearly quantitatively. DFT calculations support the proposed mechanisms induced by the protonation of the triple bond in 5-aryl-4-(arylethynyl)pyrimidines. Fluorescent properties of the obtained heterocycles are also described.

 

Guests in CMR


Delegation of embassy of Thailand has visited Center for Magnetic Resonance. Peter Tolstoy has presented a short lecture for guests.

Geosciences, 2017, 7, 24

A. Lupachev, E. Abakumov, S. Gubin

“The Influence of Cryogenic Mass Exchange on the Composition and Stabilization Rate of Soil Organic Matter in Cryosols of the Kolyma Lowland (North Yakutia, Russia)”

Geosciences, 2017, 7, 24
DOI:10.3390/geosciences7020024

source: http://www.mdpi.com/2076-3263/7/2/24

Soil organic matter (SOM) was studied in different types of organo-mineral material (from surface horizons and partially isolated materials—cryoturbated or buried horizons) sampled from the surface horizons, the central parts of the Cryosol profiles, and the lower active layer. We found that the humic acids (HAs) of the cryoturbated and buried horizons showed an increased degree of oxidation and an increment of alkylaromatic and protonized aromatic fraction content. In contrast, the HAs of the surface horizons showed increased values of alkylic carbon components. The content of free radicals was essentially higher in the surface layers than in the cryoturbated and buried layers. While the bulk soil organic matter composition (total organic carbon, total nitrogen, and aromatic/aliphatic values) was not essentially different between surface, cryoturbated, and buried horizons, there were essential differences in elemental composition, carbon species, and free radical content. This indicates that the degree of humification in cryoturbated and buried organo-mineral material is higher than in surface horizons and that partial isolation results in relative stabilization of such material in soil profiles.

 

J. Wood Chem. Technol, 2017

E.I. Evstigneyev, A.V. Kalugina, A.Yu. Ivanov, A.V. Vasilyev

“Contents of α-o-4 and β-o-4 bonds in native lignin and isolated lignin preparations”

J. Wood Chem. Technol, 2017,accepted
DOI:10.1080/02773813.2017.1297832

An analytical calculation method for the estimation of the contents of alkyl aryl ether bonds (α-O-4 and β-O-4) in lignin was developed. In the framework of the method, Alkyl–O–Aryl type bonds are described as coupled phenolic hydroxyls (OHphen). The method is based on the balance equation including the free and coupled OHphen contents in dissolved and residual lignins, on the one hand, and their respective contents in native lignin, on the other. The free OHphen content is calculated on the basis of the OHphen contents of dissolved and residual lignin, determined by the aminolysis method in the course of kraft cooking of softwood. The calculation results for soluble lignin preparations are in good agreement with the 13C NMR (nuclear magnetic resonance) spectral data for the solutions. The content of Alkyl–O–Aryl bonds in native softwood (pine, spruce) lignin was estimated at 79/100 PPU (phenylpropane unit). In isolated lignin preparations, the contents of these bonds decrease in the sequence: Freudenberg lignin (71/100 PPU)> Bjorkman lignin (61/100 PPU)> Pepper lignin (44/100 PPU). Dissolved alkaline lignin still contains small amounts of Alkyl–O–Aryl bonds (36/100 PPU in soda lignin and an average of 23/100 PPU in soda-AQ lignin, kraft lignin, and kraft-AQ lignin). Residual lignin which represents the fraction of native lignin with inter-unit bonds resistant to kraft pulping contains 66/100 PPU of such bonds. A relatively high content of Alkyl–O–Aryl bonds (61/100 PPU) is preserved in technical hydrolysis lignins.

 

MRI view of electrochemical process


MRI of electrochemical cell with FeCl2 water solution under different applied voltage. Images were obtained on Bruker 400 WB Avance III spectrometer.