Imidazol-5-one as an Acceptor in Donor-Acceptor Cyclopropanes: Cycloaddition with Aldehydes
Organic Letters. 2020. Vol. 22. No. 7. P. 2740-2745.
Mikhaylov Andrey A., Kuleshov A., Solyev P., Korlyukov A., Dorovatovskii P., Mineev K., Baranov M.
Spiro[imidazol-5-one-4,1′-cyclopropanes] behave as donor–acceptor (D–A) cyclopropanes in a formal cycloaddition reaction with aldehydes. The activation of such type of cyclopropanes is achieved with an equivalent of Brønsted acid. The reaction proceeds in high yields of 51–92% and demonstrates moderate diastereoselectivity at the quaternary stereocenter, which is determined by the electron-donating nature of the aldehyde partner. The ease of separation of stereoisomers allowed the creation of a library of 44 spiroannulated tetrahydrofurans with various substitution patterns.
Imidazolone-activated donor-acceptor cyclopropanes with a peripheral stereocenter. A study on stereoselectivity of cycloaddition with aldehydes
, , et al., Chemistry of Heterocyclic Compounds (Latvia) 2020 Vol. 56 No. 8 P. 1092-1096
Nucleophilic cyclopropanation of arylideneimidazolones possessing a peripheral chiral center and the subsequent fractional crystallization of diastereomers allows access to the compounds with an enantiomerically uniform configuration of the spirocyclic donoracceptor cyclopropane fragment. They were used to study the mechanism of the cycloaddition reaction with aldehydes; it was demonstrated that stereochemical information from the cyclopropane fragment ...
Added: September 29, 2020
, , et al., Mendeleev Communications 2021 Vol. 31 No. 5 P. 657-658
Imidazolone-activated donor–acceptor cyclopropanes undergo alcohol-assisted ring opening under the co-action of p-toluenesulfonic acid. Under the optimized conditions, cyclopropanes and alcohols are coupled in 1,3-fashion with the retention of heterocyclic fragment. Substrates with aromatic donor groups provide the addition products in 75–99% yields as mixtures of two diastereomers. ...
Added: September 13, 2021
Novel Formal [3+3] Cycloaddition of Silyl Nitronates with Activated Cyclopropanes and Its Application in the Synthesis of Pyrroline-N-oxides
, , et al., Synlett 2014 Vol. 25 No. 16 P. 2275-2280
1,1-Cyclopropane diesters with donor substituents undergo formal [3+3] cycloaddition with various silyl nitronates under Yb(OTf)3 catalysis in the presence of a proton scavenger to give target N-silyloxy tetrahydro-1,2-oxazines in 56–98% yield. The reasons determining the reaction diastereoselectivity are discussed. The resulting tetrahydro-1,2-oxazines are transformed into pyrroline-N-oxides via a novel TfOH-promoted silanol elimination reaction. ...
Added: September 30, 2020
Tandem Pd-catalyzed C–C coupling/recyclization of 2-(2-bromoaryl)cyclopropane-1,1-dicarboxylates with primary nitro alkanes
, , et al., Tetrahedron Letters 2016 Vol. 57 No. 1 P. 11-14
The first successful synthesis of 1H-2,3-benzoxazine 3-oxides has been described. The efficiency of the approach is provided by the C–C-coupling of 2-(2-bromoaryl)cyclopropane-1,1-dicarboxylates with primary nitroalkanes catalyzed by Pd(dba)2/JohnPhos system followed by in situ recyclization of the intermediates. Several representative transformations allowing selective modification of the nitronate as well as malonate functionalities in the resulting compounds are demonstrated. ...
Added: September 30, 2020
, , et al., Chemistry of Heterocyclic Compounds (Latvia) 2020 Vol. 56 No. 1 P. 108-111
4-Arylidene-1H-imidazol-5(4H)-ones react with N-benzylazomethine methylide under trifluoroacetic acid catalysis to form 9-aryl-1,3,7- triazaspiro[4.4]non-1-en-4-ones in 66–95% yields as one diastereomer in each case. ...
Added: September 29, 2020
Intricacies of Cation–Anion Combinations in Imidazolium Salt-Catalyzed Cycloaddition of CO2 Into Epoxides
, , et al., ACS Catalysis 2018 Vol. 8 No. 3 P. 2589-2594
The cycloaddition of CO2 into epoxides catalyzed by imidazolium and related salts continues to attract attention due to the industrial importance of the cyclic carbonate products. The mechanism of the imidazolium-catalyzed transformation has been proposed to require the participation of the acidic C2 proton. However, other simple salts without acidic protons, such as N,N,N,N-tetrabutylammonium chloride, are also ...
Added: October 29, 2020
Stereoselective synthesis of spirocyclic nitronates by SnCl4-promoted reaction of nitroalkenes with C-2 substituted 4-methylidene-1,3-dioxolane
, , et al., Mendeleev Communications 2015 Vol. 25 No. 6 P. 449-451
SnCl4-promoted [4 + 2] cycloaddition of β-nitrostyrenes to 4-methylidene-1,3-dioxolane provides stereoselective synthesis of spirocyclic nitronates. 2-Nitrovinyl benzoate under the same conditions produces δ-substituted nitrodiene as a single E,E-isomer. ...
Added: September 30, 2020
, , Synthesis 2021 Vol. 53 No. 20 P. 3673-3682
Five-membered heterocyclic N-oxides attract special attention due to their significant potential applications in medicinal chemistry and advanced materials science. In this regard, novel methods for their synthesis and functionalization are in constant demand. In this short review, recent state-of-the-art achievements in the chemistry of isoxazoline N-oxides, 1,2,3-triazole 1-oxides and 1,2,5-oxadiazole 2-oxides are summarized. The main ...
Added: September 12, 2022
Reply to Comment on ‘Nonlocal statistical field theory of dipolar particles in electrolyte solutions’
, Journal of Physics: Condensed Matter 2019 Vol. 31 P. 078002-078003
We reply to the comment on our paper by Budkov (2018 J. Phys.: Condens. Matter 30 344001). ...
Added: January 4, 2019
Effects of Support Structure and Composition on the Activity of Cu–Ni Catalysts for Methanol Steam Reforming
, , et al., Inorganic Materials 2019 Vol. 55 No. 12 P. 1230-1236
We have studied the catalytic activity of Cu–Ni bimetallic catalysts on yttrium-, tin-, zinc-, and niobium-doped zirconia and ceria supports for methanol steam reforming (MSR), a process for hydrogen production, and examined the effect of the nature of the dopants and annealing temperature on the structure and particle size of the oxide supports and the ...
Added: November 18, 2019
Synthesis, molecular structure and catalytic performance of heterocycle-fused cyclopentadienyl-amido CGC of Ti (IV) in ethylene (co)polymerization: The formation and precision rheometry of long-chain branched polyethylenes
, , et al., European Polymer Journal 2022 Vol. 176 Article 111397
Long-chain branching is an efficient tool to design and produce polyolefins with enhanced mechanical characteristics, physical properties, and processability. In the synthesis of long-chain branched polyethylene (LCB PE), constrained geometry complexes (CGCs) of Ti (IV) [(η5-C5Me4)SiMe2NtBu]TiX2 (X = Cl, Ti1; X = alkyl) are highly effective at elevated temperatures. However, further development of polyolefin technologies ...
Added: September 12, 2022
Synthesis of Rhodium Complexes with Chiral Diene Ligands via Diastereoselective Coordination and Their Application in the Asymmetric Insertion of Diazo Compounds into E−H Bonds
, , et al., Angewandte Chemie - International Edition 2021 Vol. 60 No. 34 P. 18712-18720
A new method for the synthesis of chiral diene rhodium catalysts is introduced. The readily available racemic tetrafluoro-benzobarrelene complexes [(R 2 -TFB)RhCl] 2 were separated into two enantiomers via selective coordination of one of them with the auxiliary S -salicyl-oxazoline ligand. One of the resulting chiral complexes with an exceptionally bulky diene ligand [( R,R ...
Added: January 24, 2023
Effect of different organic additives on the shape, size and scintillation properties of Bi4Ge3O12 powders synthesized by the microwave-hydrothermal method
, , et al., Advanced Powder Technology 2021 Vol. 32 No. 1 P. 175-185
A route for production of fine Bi4Ge3O12 (BGO) powder is sought after to lower the cost of scintillation devices and make their shapes more versatile. A systematic study of highly dispersed BGO crystallization under the hydrothermal-microwave (HTMW) conditions was carried out in the present work. Anionic, cationic and non-ionic surfactants, chelating agents and polyols were used to modify ...
Added: October 23, 2022
, , et al., Materials Research Bulletin 2022 Vol. 155 Article 111971
The phase composition, microstructure, electrical and thermal conductivity of Nd2±xHf2±xO7±δ ceramic materials have been studied. (Nd2-xHfx)Hf2O7+x/2 (x = 0.2, 0.32, 0.39) composites, containing 4–16 wt% HfO2, have the highest conductivity and the brightest narrow-band luminescence among materials under study. The (Nd2-xHfx)Hf2O7+x/2 (x = 0.2) composite, containing ~ 4 wt % HfO2, is shown to have ...
Added: July 16, 2022
, , , Журнал прикладной химии 2021 Т. 94 № 3 С. 275-295
Materials-science aspects of the development of color road pavement (color asphalt concretes) and marking are considered. Kinds of binders used as a base for color asphalt concretes are characterized; these include dark petroleum bitumens, colorless polymer binders, and biobinders. The main requirements to colorless binders are formulated. The relationship between the composition and physicochemical, mechanical, ...
Added: January 29, 2023
, , et al., Synthesis 2021 Vol. 53 No. 24 P. 4689-4699
Directly accessible 8-substituted tetrahydroquinolines undergo 1,5-hydride shift-triggered cyclization to provide hardly accessible julolidine derivatives in 20-98% yield under scandium (III) triflate catalysis. The scope of the reaction, several follow-up transformations and a remarkable side-process discovered during the conditions optimization are highlighted. ...
Added: July 29, 2021
, , et al., Polymers 2021 Vol. 13 No. 15 P. 2513
Low chemical durability of proton exchange membranes is one the main factors limiting their lifetime in fuel cells. Ceria nanoparticles are the most common free radical scavengers. In this work, hybrid membranes based on Nafion-117 membrane and sulfonic or phosphoric acid functionalized ceria synthesized from various precursors were prepared by the in situ method for ...
Added: February 3, 2022
A Planar‐Chiral Rhodium(III) Catalyst with a Sterically Demanding Cyclopentadienyl Ligand and Its Application in the Enantioselective Synthesis of Dihydroisoquinolones
, , et al., Angewandte Chemie - International Edition 2018 Vol. 57 No. 26 P. 7714-7718
The rapid development of enantioselective C−H activation reactions has created a demand for new types of catalysts. Herein, we report the synthesis of a novel planar‐chiral rhodium catalyst [(C5H2tBu2CH2tBu)RhI2]2 in two steps from commercially available [(cod)RhCl]2 and tert‐butylacetylene. Pure enantiomers of the catalyst were obtained through separation of its diastereomeric adducts with natural (S)‐proline. The catalyst promoted enantioselective ...
Added: September 29, 2020
Adsorption of molecular oxygen on the Ag(111) surface: A combined temperature-programmed desorption and scanning tunneling microscopy study
, , et al., Journal of Chemical Physics 2018 Vol. 148 No. 24 Article 244702
The adsorption of O-2 on Ag(111) between 300 and 500 K has been studied with temperature-programmed desorption (TPD) and scanning tunneling microscopy (STM). At the first stage of adsorption, the disordered local oxide phase (commonly looking in STM as an array of black spots) is formed on the surface irrespective of the substrate temperature. The maximum concentration of black spots was found to be approximate to 0.11 ML, which corresponds to an oxygen coverage of approximate to 0.66 ML. Taking into account that the nucleation of the Ag(111)-p(4 x 4)-O phase starts after the saturation of the disordered phase, one ...
Added: October 25, 2021
, , Polymer Science - Series C 2018 Vol. 60 No. Supplement 1 P. 148-159
Theoretical models of the conformational behavior of flexible polymer chains in mixed solvents enunciated in the world literature during the last decade are critically reviewed. Models describing different mechanisms of coil-to-globule transitions in a good solvent induced by cosolvent addition are highlighted. Special attention is given to the analysis of theoretical approaches to describing the ...
Added: November 30, 2018
Диффузионные свойства гетерогенных мембран, допированных оксидом циркония с функционализированной поверхностью
, , , Журнал неорганической химии 2015 Т. 60 № 11 С. 1551-1553
The properties of hybrid materials based on the MK-40 heterogeneous membrane, the MF-4SK homogeneous membrane, and zirconium oxide with a functionalized surface are studied. The ionic conductivity and diffusion parameters of these materials were studied. The presence of the asymmetry effect of diffusion permeability and mutual diffusion of HCl and NaCl solutions through the studied ...
Added: November 13, 2019
, , et al., Batteries 2022 Vol. 8 No. 8 Article 98
Nanostructure composites Ge-Co-P with brutto-composition CoGe2P0.1, or CoGe2@GeP were manufactured via electrolysis of aqueous electrolyte. Such composites are able to reversible insertion of lithium and sodium with specific capacities up to 855 and 425 mAh/g, respectively. The main advantage of the composites consists in their excellent cycleability. ...
Added: November 25, 2022
Evaluation of the Possibility to Use Coalbed Methane to Produce Methanol Both by Direct Partial Oxidation and From Synthesis Gas
, , et al., Eurasian Chemico-Technological Journal 2022 Vol. 24 No. 2 P. 157-163
The possibility of using coalbed methane to produce methanol is assessed. Methanol can be obtained from methane both by direct partial oxidation and from synthesis gas formed through the oxidative conversion of methane. Thermodynamic analysis of coalbed methane conversion was carried out to determine the conditions for obtaining synthesis gas with the ratio [H2 ]/[CO] = ...
Added: October 7, 2022
Synthesis of Diazanorcaradienes and 1,2-Diazepines via the Tandem [4+2]-Cycloaddition/Retro-[4+2]-Cycloaddition Reaction between Methoxycarbonylcyclopropenes and Dimethoxycarbonyltetrazine
, , et al., European Journal of Organic Chemistry 2019 Vol. 2019 No. 26 P. 4133-4138
The reaction of di(methoxycarbonyl)tetrazine with substituted cycloprop-2-ene-1-carboxylates gives a series of 3,4-diazanorcaradienes and 1,2-diazepines. The influence of the nature of cyclopropenes and the reaction conditions on its selectivity was investigated. The addition of nucleophiles to norcaradienes was studied and a rare example of the “walk” rearrangement in this class of compounds was revealed. ...
Added: October 12, 2019