Doklady Chemistry最新文献

Nitrile-containing azoloazines with a bridged nitrogen atom are of interest as molecules with potential antiviral and antidiabetic activity. To date, a few corresponding 7-aminoazolo[1,5-a]pyrimidine-6-carbonitriles has been described in the literature and there is no universal method for their synthesis, which limits the possibility to optimize structure for preparing derivatives with prescribed biological activity. In the present work, we have studied different conditions for cyclocondensation of aminoazoles and (ethoxymethylidene)malononotrile; we have shown that optimal method for synthesis of 7-aminoazolo[1,5-a]pyrimidine-6-carbonitriles is the heating of initial components in pyridine. This method provides a library of different nitrileazolopyrimidines containing both electron-donating and electron-withdrawing substituents in the azole fragment.

The review highlights the recently discovered superbase-promoted self-organization of complex molecular structures of great synthetic significance with the participation of acetylene (a large-tonnage industrial feedstock) and simple available nucleophilic molecules. The self-organization comprises a concerted sequence of elementary chemical stages involving several molecules of acetylene, which ultimately leads to a one-pot synthesis of complex highly reactive molecular systems structurally close to essential natural compounds. This new phenomenon in organic chemistry fundamentally expands the possibilities of acetylene-driven fine organic synthesis and meets the requirements of green chemistry (one pot, atom and energy economy, theoretical waste-free production, low carbon footprint).

Novel thioethers with nitrogen- and oxygen-containing heterocyclic moieties and a redox-active catechol group were synthesized. The radical scavenging and antioxidant activities of the compounds were studied in reactions with synthetic radicals and in the DNA oxidative damage. The catechols with nitrogen-containing heterocyclic substituents or a furan ring showed pronounced radical scavenging activity in reactions with diphenylpicrylhydrazyl or generated 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation. In the case of DNA oxidative damage, a dual anti/pro-oxidant effect was found. Catechol thioethers with methoxybenzoxazole or furan rings showed the highest activity in all biological assays.

Nickel-catalyzed N-arylation of C-amino-1,2,4-triazoles with arylboronic acids was studied for the first time. An efficient catalytic system based on nickel chloride and phenanthroline was developed and a new method for the preparation of 1-substituted 3(5)-arylamino-1,2,4-triazoles was proposed.

In this work, we used a recently proposed concept of bio-Profiles and bio-Factors for studying the solvent contribution into the “overall cytotoxicity” of chemical reactions by the example of synthesis of 1,1'-biphenyl from aryl halide and phenylboronic acid. Two standard solvents (ethanol and N-methylpyrrolidone) and four ionic liquids (1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, and cholinium bis(trifluoromethylsulfonyl)imide) were analyzed.

This paper presents the scientific and technological principles of electrochemical removal of diffusible hydrogen by reactions of hydroxyl and hydrogen in molten aluminum fluoride slag and in the gas phase. A model was proposed for the electrochemical processes in the weld pool with the formation of aluminum fluoride polymer clusters in TiO₂–CaF₂–Na₃AlF₆ slag to reduce the content of diffusible hydrogen, decrease the volume of slag inclusions, and improve the mechanical properties of bainitic steel welded joints.

A study was made of glass samples obtained from highly purified natural quartz, synthetic silica, and glass grit made of synthetic quartz crystals smelted according to a technology that included elements of the KS-4V technology. It was determined that the transmission spectra of the glasses smelted from various materials have differences in the UV and IR regions.

The Bu₄NI/t-BuOOH oxidative system is widely used in organic synthesis, but mechanistic principles underlying its reactivity are only partially explored. In this work, drawing on the example of the oxidative C–O coupling reaction between compounds with a carbonyl group and (or) a benzyl moiety with N-hydroxyphthalimide, it has been discovered that the coupling with the CH-acidic fragment of the carbonyl group proceeds via ionic mechanism, and the coupling with the benzyl fragment proceeds via radical mechanism. When dimethylacetamide is used as a solvent, the ionic process with the participation of the carbonyl group prevails, while in MeCN the radical process involving the benzyl moiety is realized along with the ionic process. For the oxidative C–O coupling with participation of the benzyl moiety without affecting the α-CH fragment of the carbonyl group, it is advisable to use PhI(OAc)₂, Ce(NH₄)₂(NO₂)₆, or t‑BuOOt-Bu as oxidants for which only radical pathway is characteristic.

A possibility of preparation of 1,2,4-triazines with a residue of 2-amino-1,3,4-thiadiazoles at the C5 position by the solvent-free reaction of ipso-amination of 3,6-di(het)aryl-1,2,4-triazine-5-carbonitriles has been studied. It has been found that the reaction also leads to the corresponding 5-amino-1,2,4-triazines as minor products.

Transformation of H₂PtCl₆ over time under the action of 2-octanol has been studied by NMR, IR spectroscopy, GLC, and GC/MS. It has been found for the first time that the alcohol in a H₂PtCl₆ ⋅ 6H₂O–2-octanol solution is hydrochlorinated to give 2-chlorooctane. Dehydrated platinum chlorides catalyze the elimination of methyl groups in trimethylchlorosilane and hexamethyldisiloxane, which leads to the formation of polydimethylsiloxanes. It has been assumed that the resulting π-complex of H₂PtCl₄ with octene-1 is not stable in a hydrochloric medium and rapidly decomposes to release chloroalkyl.