bluuebunny/crossref_metadata_2025 huggingface dataset:
On Some Extremal Problems Associated with Motion in a Velocity Field
Authors: Nikolenko P. V
Published: April 2024

The extremals of the Pontryagin maximum principle for problems related to motion in the velocity field are studied. Controls are continuous functions. It is shown that in the state space there exists a neighborhood of the final point through each point of which there passes a single extremal trajectory leading to the final point. It is also shown that if the trajectory of an extremal contains a point that another extremal with the same value of the functional passes through, then this point cuts off the nonoptimal part from the trajectory. It is proved that the remaining part leading to the final point is optimal.
Retraction Note: Proof of the Jacobian Conjecture in the Two-Dimensional Case and Global Isochronous Centers of Polynomial Hamiltonian Differential Systems
Authors: Amel'kin V. V
Published: April 2024

The author has retracted this article. The main results of the work, namely Theorem 1 and the corollaries arising from it, have not been strictly proven: formulas (8) are valid only under the condition. Yet, even when the indicated condition is met, formulas (9) need to be proven. Because of this, this work in its current form should be recognized as incorrect. The author is grateful to Professor L.G. Makar-Limanov, who drew attention to the lack of correct proof of formula (8) and Professor V.V. Bakhtin, who pointed to other inaccurate statements in this article.
Inverse Problem of Determining the Unknown Coefficient in the Beam Vibration Equation in an Infinite Domain
Authors: Durdiev U. D
Published: April 2024

For the equation of transverse vibrations of a homogeneous beam, we consider the direct initial value problem in an infinite domain and study the inverse problem of determining the time-dependent beam stiffness coefficient. The solution of the direct problem is given with the help of fundamental solutions, and the existence and uniqueness of this solution are proved. Stability estimates are obtained for the solution of the inverse problem. Existence and uniqueness theorems for the solution of the inverse problem are proved using Banach’s contraction mapping principle.
On a Class of Control Problems with Mixed Constraints
Authors: Arutyunov A. V , Karamzin D. Yu
Published: April 2024

An optimal control problem with a nonregular mixed constraint linear in the control variable is studied. Necessary optimality conditions are proposed in the form of Pontryagin’s maximum principle for such a class of problems. The corresponding examples are considered.
Asymptotic Properties of a Class of Systems with Linear Delay
Authors: Grebenshchikov B. G , Lozhnikov A. B
Published: April 2024

Sufficient conditions for the asymptotic stability of linear systems of differential equations with linear delay are obtained. On the basis of these conditions, some systems of linear differential equations are studied, and one of them is stabilized on an infinite time interval.
Spectral Properties of a Singular Differential Operator on an Interval with Transmission Conditions
Authors: Lomov I. S
Published: April 2024

We study the first boundary value problem for a second-order differential operator with a singular coefficient on an interval with transmission conditions at an interior point. Asymptotic formulas are obtained for the eigenfunctions and eigenvalues of both the original and the adjoint operator. The completeness and unconditional basis property of the eigenfunction systems of these operators in the space of square integrable functions on the interval are established. Il’in’s method and Il’in’s conditions are applied to establish the Bessel inequality.
On the Control of the Spectra of Upper Strong Oscillation Exponents of Signs, Zeros, and Roots of Third-Order Differential Equations
Authors: Stash A. Kh
Published: April 2024

We construct an example of a third-order linear homogeneous differential equation with continuous coefficients on the half-line whose spectra of upper strong oscillation exponents of the signs, zeros, and roots coincide with a given Souslin set containing zero in the nonnegative half-line of the extended real line.
On the Darboux Problem for Hyperbolic Systems
Authors: Mironov A. N , Mironova L. B
Published: April 2024

For a hyperbolic system with simple characteristics in the-dimensional space of independent variables, the existence and uniqueness of a solution of the Darboux problem is proved. The Riemann–Hadamard matrix is determined, and the solution of the Darboux problem is constructed in terms of this matrix. As an example of application of the results, the solution of the Darboux problem for a system with four independent variables is constructed in detail.
On the Effect of Irregularity of the Domain Boundary on the Solution of a Boundary Value Problem for the Laplace Equation
Authors: Rossovskiy L. E , Shamin R. V
Published: April 2024

We consider an inhomogeneous boundary value problem with mixed boundary conditions for the Laplace equation in a domain representing a perturbationof a rectangle where one of its sides is replaced by some curve of minimal smoothness. An estimate is obtained for the difference between the solutions of the perturbed and unperturbed problems in the norm of the Sobolev space on their common domain.
On the Existence of Solutions of Nonlinear Boundary Value Problems for a System of Differential Equilibrium Equations for Timoshenko-Type Shells in Isometric Coordinates
Authors: Timergaliev S. N
Published: April 2024

We prove the existence of solutions of a boundary value problem for a system of five nonlinear second-order partial differential equations with given nonlinear boundary conditions, which describes the equilibrium state of elastic shallow inhomogeneous isotropic shells with free edges in the Timoshenko shear model referred to isometric coordinates. The boundary value problem is reduced to a nonlinear operator equation for generalized displacements in the Sobolev space, the solvability of which is established using the contraction mapping principle.
On the Existence of Solutions of Degenerate Discrete-Time Systems
Authors: Shcheglova A. A
Published: April 2024

We consider a nonstationary linear discrete-time descriptor system with rectangular matrix coefficients defined on a finite horizon. An answer is obtained to the question as to what the largest number of unknown vectors that can be found from a given finite number of equations is. In a similar way, the solvability of nonstationary linear continuous- or discrete-time systems, as well as (in the local sense) nonlinear discrete-time systems, is studied. It is shown that in cases where the considered linear (or nonlinear) system retains its internal structure, it is possible to find its solutions on an infinite horizon. The proposed approach has sufficient generality and automatically solves the problem of consistency of the initial data.
Ellipticheskie zadachi i integral'nye uravneniya v prostranstvakh razlichnoy gladkosti po peremennym
Authors: Vasil'ev A. V , Vasil'ev V. B
Published: April 2024

We consider a model elliptic pseudodifferential equation and the simplest boundary value problems in a quadrant in a Sobolev–Slobodetsky space of different orders of smoothness in different variables. In the case of a special representation of the symbol, we describe a general solution of the equation and consider the simplest boundary value problem with the Dirichlet and Neumann conditions on the sides of the quadrant. This boundary value problem is reduced to a system of integral equations, which, under additional assumptions about the structure of the symbol, can also be reduced to a system of first-order difference equations
Dvumernye zadachi fil'tratsii zhidkosti s granichnymi istochnikami v anizotropnom neodnorodnom sloe
Authors: Piven' V. F
Published: April 2024

We study the first and second boundary value problems and the transmission problem for the complex potential of a two-dimensional filtration flow in an anisotropic and inhomogeneous (variable permeability and thickness) porous layer. The flow sources are arbitrary discrete and can generally be located both on the boundaries and outside the boundaries. The boundaries are modeled by arbitrary smooth (piecewise smooth) closed lines, and the flow sources are singularities (isolated singular points) of the complex potential. The presence of a system of sources on the boundaries leads to a fundamentally new generalization (complication) of the boundary conditions, which are characterized by singular functions with isolated singular points. In the case of an anisotropic homogeneous (constant permeability and thickness) layer and rectilinear boundaries, the solutions of the problems are presented in closed form. In the general case, when an arbitrary smooth closed curve models a boundary with sources located on it, a generalized Cauchy type integral for the complex flow potential is used. This permitted reducing the second boundary value problem and the transmission problem to boundary singular integral equations. The problems studied are mathematical models of two-dimensional filtration processes in layered porous media, which are of interest, for example, for the practice of extracting fluids (oil, water) from natural anisotropically heterogeneous soil layers.
Ob approksimatsii poverkhnostnykh proizvodnykh funktsiy s primeneniem integral'nykh operatorov
Authors: Setukha A. V
Published: April 2024

Integral formulas are presented for approximating the surface gradient (of a scalar function given on a surface) and divergence (of a tangent vector field given on a surface) that are analogs of the well-known formulas for the derivatives of a function on a plane. Estimates of the error in the approximation of these functions are obtained. The question of subsequent approximation of the integrals that give expression for the surface gradient and divergence by quadrature sums over the values of the function under study at the nodes selected on the cells of the unstructured grid approximating the surface is also considered.
O razrushenii resheniya odnoy zadachi dlya sobolevskogo uravneniya s nekoertsitivnym istochnikom
Authors: Artem'eva M. V , Korpusov M. O
Published: April 2024

We consider an initial–boundary value problem for a nonlinear Sobolev-type second-order differential equation with a noncoercive source describing the behavior of charges in a semiconductor plasma in an external field. The local solvability of this problem is proved, and upper bounds are obtained for the solution blow-up time.
Sushchestvovanie i edinstvennost' klassicheskogo resheniya pervoy kraevoy zadachi dlya parabolicheskikh sistem na ploskosti
Authors: Konenkov A. N
Published: April 2024

We consider the first boundary value problem for uniformly parabolic systems of the second order with one spatial variable in bounded and semibounded domains with nonsmooth lateral boundaries. The coefficients of the system satisfy the Hölder condition and do not depend on the time variable. For continuous initial and boundary functions, the existence and uniqueness of the classical solution of this problem is established
Raznostnye skhemy dekompozitsii na osnove rasshchepleniya resheniya i operatora zadachi
Authors: Vabishchevich P. N
Published: April 2024

Domain decomposition methods are used for the approximate solution of boundary value problems for partial differential equations on parallel computing systems. The specifics of nonstationary problems is most completely taken into account when using noniterative domain decomposition schemes. Regionally additive schemes are constructed on the basis of various classes of splitting schemes. A new class of domain decomposition schemes with an additive representation of the solution on a new time level is distinguished that is based on splitting the domain into subdomains based on a partition of unity. An example of the Cauchy problem for first-order evolution equations with a positive self-adjoint operator in a finite-dimensional Hilbert space is considered. Unconditionally stable two- and three-level splitting schemes are constructed for the corresponding system of equations.
Setochno-kharakteristicheskiy metod povyshennogo poryadka dlya sistem giperbolicheskikh uravneniy s kusochno-postoyannymi koeffitsientami
Authors: Khokhlov N. I , Petrov I. B
Published: April 2024

A new approach is considered for increasing the order of accuracy of the grid-characteristic method in the region of coefficient jumps. The approach is based on piecewise polynomial interpolation for schemes of the second and third orders of accuracy for the case where the interface between the media is consistent with a finite-difference grid. The method is intended for numerical simulation of the propagation of dynamic wave disturbances in heterogeneous media. Systems of hyperbolic equations with variable coefficients are used to describe the considered physical processes. The description of the numerical method and the results of its testing are given.
Existence and Stability of Solutions with Internal Transition Layer for the Reaction–Diffusion–Advection Equation with a KPZ-Nonlinearity
Authors: Nefedov N. N , Orlov A. O
Published: April 2024

We study a boundary value problem for a quasilinear reaction–diffusion–advection ordinary differential equation with a KPZ-nonlinearity containing the squared gradient of the unknown function. The noncritical and critical cases of existence of an internal transition layer are considered. An asymptotic approximation to the solution is constructed, and the asymptotics of the transition layer point is determined. Existence theorems are proved using the asymptotic method of differential inequalities, the Lyapunov asymptotic stability of solutions is proved by the narrowing barrier method, and instability theorems are proved with the use of unordered upper and lower solutions.
Solution of a Singularly Perturbed Mixed Problem on the Half-Line for a Parabolic Equation with a Strong Turning Point of the Limit Operator
Authors: Eliseev A. G , Ratnikova T. A , Shaposhnikova D. A
Published: April 2024

We study singularly perturbed problems in the presence of spectral singularities of the limit operator using S.A. Lomov’s regularization method. In particular, a regularized asymptotic solution is constructed for a singularly perturbed inhomogeneous mixed problem on the half-line for a parabolic equation with a strong turning point of the limit operator. Based on the idea of asymptotic integration of problems with unstable spectrum, it is shown how regularizing functions and additional regularizing operators should be introduced, the formalism of the regularization method for this type of singularity is described in detail, this algorithm is justified, and an asymptotic solution of any order in a small parameter is constructed.
The Problem of Two-Dimensional String Vibrations with a Nonlinear Condition
Authors: Zvereva M. B
Published: April 2024

We study a model of small spatial transverse vibrations of a string where the deviation of any of its points from the equilibrium is characterized by two coordinates. It is assumed that in the course of vibrations one end of the string is inside a bounded closed convex set С belonging to a plane @ perpendicular to the segment along which the string is stretched. In turn, the set C can move in the plane @, with its motion given by a mapping. The end of the string remains free until it touches the boundary of the set. After coming into contact, they move together. A formula representing the solution of the initial–boundary value problem describing this vibration process is obtained. The problem of boundary control of the vibration process is considered.
Estimates of Integrally Bounded Solutions of Linear Differential Inequalities
Authors: Klimov V. S.
Published: April 2024

We study integrally bounded solutions of the differential equation A(x)=z, where A is a linear differential operator of order l defined on functions x:R→H (R=(−∞,∞), H () and H is a finite-dimensional Euclidean space). The right-hand side z is an integrally bounded function on R ranging in H and satisfying the inequality (ψ(t),z(t))≥δ|z(t)|, t∈R, δ0. Conditions are given on the operator A and the function ψ:R→H that guarantee an inverse inequality of the following form for the solutions x under consideration: ∫τ+1τ|x(l)(t)|dt≤c∫τ+2τ−1|x(t)|dt, where the constant is independent of the choice of a real number t and function x.
Construction of Polynomial Eigenfunctions of a Second-Order Linear Differential Equation
Authors: Kruglov V. E.
Published: April 2024

A system of third-order recurrence relations for the coefficients of polynomial eigenfunctions (PEFs) of a differential equation is solved. A recurrence relation for three consecutive PEFs and a formula for differentiating PEFs are obtained. We consider differential equations one of which generalizes the Hermite and Laguerre differential equations and the other is a generalization of the Jacobi differential equation. For these equations, we construct functions bringing them to self-adjoint form and find conditions under which these functions become weight functions. Examples are given where the PEFs for nonweight functions do not have real zeros.
Approximation to the Sturm–Liouville Problem with a Discontinuous Nonlinearity
Authors: Potapov D. K.
Published: April 2024

We consider a continuous approximation to the Sturm–Liouville problem with a nonlinearity discontinuous in the phase variable. The approximating problem is obtained from the original one by small perturbations of the spectral parameter and by approximating the nonlinearity by Carathéodory functions. The variational method is used to prove the theorem on the proximity of solutions of the approximating and original problems. The resulting theorem is applied to the one-dimensional Gol’dshtik and Lavrent’ev models of separated flows
On the Existence of an Infinite Spectrum of Damped Leaky TE-Polarized Waves in an Open Inhomogeneous Cylindrical Metal–Dielectric Waveguide Coated with a Graphene Layer
Authors: Smirnov Yu. G. , Smol'kin E. Yu.
Published: April 2024

We consider the problem of leaky waves in an inhomogeneous waveguide structure covered with a layer of graphene, which is reduced to a boundary value problem for the longitudinal components of the electromagnetic field in Sobolev spaces. A variational statement of the problem is used to determine the solution. The variational problem is reduced to the study of an operator function. The properties of the operator function necessary for the analysis of its spectral properties are investigated. Theorems on the discreteness of the spectrum and on the distribution of the characteristic numbers of the operator function on the complex plane are proved.
Integral Equations of Volterra Typewith Two Boundary and One Interior Singular Point
Authors: Radzhabov N. , Radzhabova L. N.
Published: April 2024

Explicit solutions of model and nonmodel integral equations of Volterra type with two boundary and one interior singular point are obtained, and the properties of the resulting solutions are studied. The well-posed statement of problems with conditions specified on singular manifolds is found in the case where the solution of the model equation contains an arbitrary constant.
Fredholm Integral Equation for Problems of Acoustic Scattering by Three-Dimensional Transparent Structures
Authors: Samokhin A. B. , Samokhina A. S. , Yurchenkov I. A.
Published: April 2024

We consider the differential and integral statements of problems of acoustic scattering by three-dimensional bounded transparent structures described by an integral equation. The results of the numerical solution of the integral equation describing the class of problems under consideration are presented. A theorem on existence and uniqueness of the solution is proved.
On the Optimality Conditions in the Weight Minimization Problem for a Shell of Revolution at a Given Vibration Frequency
Authors: Arabyan M. O.
Published: April 2024

We consider shallow elastic shells with a given circular boundary and seek an axisymmetric shell shape minimizing the weight at a given fundamental frequency of shell vibrations. Using the resulting formula for the linear part of the increment of the frequency functional, the multiplicity of the minimum natural frequency of vibrations of the shell is estimated. The Fréchet differentiability of the frequency functional is also established, and optimal conditions for minimizing the weight of the shell at a given fundamental vibration frequency are obtained.
Dirichlet Problem on the Half-Line for an Abstract Euler–Poisson–Darboux Equation Containing Powers of an Unbounded Operator
Authors: Glushak A. V
Published: April 2024

We consider an abstract Euler–Poisson–Darboux equation containing powers of an unbounded operator that is the generator of a Bessel operator function. Sufficient conditions for the unique solvability of the Dirichlet problem on the half-line are obtained. The question concerning the convergence of the solution to zero at infinity is investigated. Examples are given.
Influence of Nonisolated Singularities in a Lower-Order Coefficient of the Bitsadze Equation on the Statement of Boundary Value Problems
Authors: Rasulov A. B
Published: April 2024

We study the influence of nonisolated singularities (i.e., singularities along closed lines lying inside the domain) in the lower-order coefficients of the Bitsadze equation on the statement of boundary value problems. We discover that the conditions on the boundary of the domain in the Riemann–Hilbert problem are not sufficient for the solution; therefore, we consider a problem that combines elements of the Riemann–Hilbert problem on the boundary of the domain and the linear conjugation problem on the circles that support the singularities of the coefficients lying inside the domain. Using an appropriate refinement of Kellogg’s theorem on the conformal mapping of this domain onto a disk, we study the solvability of the problem
Cauchy Problem for the Nonlinear Liouville Equation in the Class of Periodic Infinite-Gap Functions
Authors: Khasanov A. B , Normurodov Kh. N , Khudaerov U. O
Published: April 2024

The inverse spectral problem method is used to integrate the nonlinear Liouville equation in the class of periodic infinite-gap functions. The evolution of the spectral data of the periodic Dirac operator whose coefficient is a solution of the nonlinear Liouville equation is introduced. The solvability of the Cauchy problem for an infinite system of Dubrovin differential equations in the class of three times continuously differentiable periodic infinite-gap functions is proved. It is shown that the sum of a uniformly convergent function series constructed by solving the Dubrovin system of equations and using the first trace formula satisfies the Liouville equation.
On the Multiple Spectrum of a Problem for the Bessel Equation of an Integer Order with Squared Spectral Parameter in the Boundary Condition
Authors: Kapustin N. Yu
Published: April 2024

The problem for the Bessel equation of an integer order with complex physical and spectral parameters in the boundary condition is considered. The spectral parameter enters the boundary condition quadratically. The question of the basis property of the system of eigenfunctions in the case of the appearance of a multiple eigenvalue is studied
Behavior of Trajectories of a Four-Dimensional Model of HIV Infection
Authors: Kanatnikov A. N. , Tkacheva O. S.
Published: April 2024

A model of interaction between the human immunodeficiency virus and the human immune system is considered. Equilibria in the state space of the system and their stability are analyzed, and the ultimate bounds of the trajectories are constructed. It has been proved that the local asymptotic stability of the equilibrium corresponding to the absence of disease is equivalent to its global asymptotic stability. The loss of stability is shown to be caused by a transcritical bifurcation.
On the Existence of Global Compactly Supported Weak Solutions of the Vlasov–Poisson System with an External Magnetic Field
Authors: Skubachevskiy A. L.
Published: April 2024

We consider the first mixed problem for the Vlasov–Poisson system with an external magnetic field in a domain with piecewise smooth boundary. This problem describes the kinetics of a two-component high-temperature plasma under the influence of a self-consistent electric field and an external magnetic field. The existence of global weak solutions is proved. In the case of a cylindrical domain, sufficient conditions are obtained for the existence of global weak solutions with supports in a strictly internal cylinder; this corresponds to the confinement of high-temperature plasma in a mirror trap.
On the Relationship Between the Pontryagin Maximum Principle and the Hamilton–Jacobi–Bellman Equation in Optimal Control Problems for Fractional-Order Systems
Authors: Gomoyunov M. I.
Published: April 2024

We consider the optimal control problem of minimizing the terminal cost functional for a dynamical system whose motion is described by a differential equation with Caputo fractional derivative. The relationship between the necessary optimality condition in the form of Pontryagin’s maximum principle and the Hamilton–Jacobi–Bellman equation with so-called fractional coinvariant derivatives is studied. It is proved that the costate variable in the Pontryagin maximum principle coincides, up to sign, with the fractional coinvariant gradient of the optimal result functional calculated along the optimal motion.
On a Problem of Calculating the Solvability Set for a Linear System with Uncertainty
Authors: Mel'nikova A. A. , Tochilin P. A.
Published: April 2024

We consider a linear-convex control system defined by a set of differential equations with continuous matrix coefficients. The system may have control parameters, as well as uncertainties (interference) the possible values of which are subject to strict pointwise constraints. For this system, over a finite period of time, taking into account the constraints, we study the problem of guaranteed hitting the target set from a given initial position despite the effect of uncertainty. The main stage of solving the problem is the construction of an alternating integral and a solvability set. To construct the latter, the greatest computational complexity is the calculation of the geometric difference between the target set and the set determined by the uncertainty. A two-dimensional example of this problem is considered for which a method is proposed for finding the solvability set without the need to calculate the convex hull of the difference of the support functions of the sets.
On the Construction of the Graph of Discrete States of a Switched Affine System
Authors: Fursov A. S. , Krylov P. A.
Published: April 2024

The problem of constructing the graph of states of a switched affine system closed by a static state feedback is considered. To solve this problem, a constructive algorithm based on the study of the consistency of systems of linear algebraic inequalities is proposed.
Analysis of a Multipoint Boundary Value Problem for a Nonlinear Matrix Differential Equation
Authors: Bondarev A. N. , Laptinskiy V. N.
Published: April 2024

For a nonlinear differential matrix equation, we study a multipoint boundary valueproblem by a constructive method of regularization over the linear part of the equation usingthe corresponding fundamental matrices. Based on the initial data of the problem, sufficientconditions for its unique solvability are obtained. Iterative algorithms containing relativelysimple computational procedures are proposed for constructing a solution. Effective estimatesare given that characterize the rate of convergence of the iteration sequence to the solution, aswell as estimates of the solution localization domain.
Cauchy Problem for the Loaded Korteweg–de Vries Equation in the Class of Periodic Functions
Authors: Khasanov A. B. , Khasanov T. G.
Published: April 2024

The inverse spectral problem method is applied to finding a solution of the Cauchyproblem for the loaded Korteweg–de Vries equation in the class of periodic infinite-gap functions.A simple algorithm for constructing a high-order Korteweg–de Vries equation with loaded termsand a derivation of an analog of Dubrovin’s system of differential equations are proposed. Itis shown that the sum of a uniformly convergent function series constructed by solving theDubrovin system of equations and the first trace formula actually satisfies the loaded nonlinearKorteweg–de Vries equation. In addition, we prove that if the initial function is a real π-periodicanalytic function, then the solution of the Cauchy problem is a real analytic function in thevariable x as well, and also that if the number π/n, n ∈ N, n ≥ 2, is the period of the initialfunction, then the number π/n is the period for solving the Cauchy problem with respect to thevariable x.
Solution of the Cauchy Problem for One Degenerate Equation with the Dzhrbashyan–Nersesyan Fractional Derivative
Authors: Irgashev B. Yu.
Published: April 2024

A solution of the Cauchy problem is obtained for one degenerate equation withthe Dzhrbashyan–Nersesyan fractional derivative, particular solutions of which are representedusing the Kilbas–Saigo function.
Synthesis of 2-(16,17-Epoxy-3β,20-dihydroxypregn-5-en-20-yl)1,3-dithiane
Authors: Valiullina Z. R , Khasanova L. S , Miftakhov M. S
Published: April 2024

The synthesis of 3β,20-dihydroxy-5-pregnene-16,17-epoxy-20-dithian, a new promising synthon for obtaining of OSW-1 aglycone and its analogues, was carried out from diosgenin. In an alternative approach, a “low-temperature” version of the decyclization of the F-ring of diosgenin by the action of the Et3SiOTf-(CF3CO)2O- CH2Cl2 system was implemented to form pseudodiosgenin bis-trifluoroacetate, followed by transformation into a key block.
The first example of synthesis of a new class of spiroboracarbocycles via cycloboration of methylenecycloalkanes with PhBCl2 catalyzed by Cp2TiCl2
Authors: Tulyabaeva L. I , Salakhutdinov R. R , Tyumkina T. V , Tulyabaev A. R , Dzhemilev U. M
Published: April 2024

Cp2TiCl2-catalyzed cycloboration of methylenecycloalkanes with PhBCl2 in the presence of metallic Mg to obtain a novel spiroboracarbocycles in good yields (70-80%) is reported for the first time. The structure and properties of spiro-fused boriranes were studied using 11B, 1H, 13C NMR spectroscopy and DOSY experiments. 1-Phenyl-substituted boraspiranes are stable in solution at room temperature for a day.
Synthesis of 5,7-dichloro-2-adamantanone
Authors: Skomorokhov M. Yu. , Zaborskaya M. S , Ivleva E. A , Shiryaev A. K , Klimochkin Yu. N.
Published: April 2024

The reaction of 2-adamantanecarboxylic acid with an excess of chlorine in the presence of AlCl3 under heating gave 5,7-dichloro-2-adamantanecarboxylic acid. This product was sequentially introduced into the Curtius, deamination, and oxidation reactions to form 5,7-dichloro-2-adamantanone. The resulting product is a key substrate for synthesis of new substances and materials with a set of practically important properties, including both the synthesis of biologically active molecules and systems for chemiluminescent diagnostic methods.
Reactions of 1,3-dihaloadamantanes with nitric acid
Authors: Ivleva E. A , Simatova E. V , Klepikov V. V , Khatmullina Yu. E. , Klimochkin Yu. N.
Published: April 2024

The reaction of 1,3-dibromoadamantanes with fuming nitric acid gave the mixture of 2-oxaadamantane derivatives. In the same conditions 1,3-diiodoadamantanes gave the corresponding 1,3-dinitroxyadamantanes. A preparative method for the synthesis of 5,7-dimethyl-3-bromomethyl-1-hydroxy-2-oxaadamantan-1-ol from 5,7-dimethyl-1,3-dibromoadamantane was developed. The obtained compounds can be used in the directed synthesis of substances with high molecular complexity for studying of biological activity.
Chemical transformations of 3-bromoethyl-5,7-dimethyl2-oxaadamantan-1-ol in sulfuric acid
Authors: Ivleva E. A , Simatova E. V , Zaborskaya M. S , Kazachkova M. S , Rybakov V. B , Klimochkin Yu. N.
Published: April 2024

The reactions of 3-bromomethyl-5,7-dimethyl-2-oxaadamantan-1-ol in a 96% acid medium both in the presence and in the absence of nucleophiles were studied. During the reactions a number of structural transformations of the 2-oxaadamantane cage take place. The possibility of obtaining 1,2,3-trisubstituted adamantanes is also presented. The structural features of new compounds are investigated using 2D NMR spectroscopy and XRD analysis. The obtained compounds can be used in the directed synthesis of a new cage heterocycles for studying of biological activity.
Synthesis of chiral bispidine-based macrocycles
Authors: Gaisen S. V , Medved'ko A. V , Vatsadze S. Z
Published: April 2024

The first representatives of chiral ferrocenophanes based on bispidines have been synthesized. It is shown that their structure in solution is similar to the previously described achiral ferrocenophane.
One-pot synthesis of 3-carbomoyl-2-oxo-1,2-dihydropyridine-4-carboxylic acid
Authors: Fedoseev S. V , Lipin K. V , Ershov O. V
Published: April 2024

A one-pot method for the synthesis of 3-carbomoyl-2-oxo-1,2-dihydropyridine-4-carboxylic acids has been developed, which consists in the interaction of 4-oxoalkane-1,1,2,2-tetracarbonitriles with water and the hydrolysis of the resulting mixture of 2-oxo-1, 2-dihydropyridine-3,4-dicarbonitrile and 2-oxo-4-cyano-1,2-dihydropyridine-3-carboxamide with sodium hydroxide solution.
Semicarbazones of acetyldihydropyrans: diastereoselective acetylene-based two-step synthesis
Authors: Tatarinova I. V , Lobanova N. A , Ushakov I. A , Schmidt E. Yu. , Trofimov B. A
Published: April 2024

2-Acetyl-3,4-dihydropyrans (diastereoselectively synthesized from acetylene and aromatic ketones in a one synthetic operation) reacted with semicarbazide hydrochloride to stereoselectively form semicarbazones of E -configuration in up to 86% yield.
Gold-catalysed synthesis of 4-(trifluoromethyl)quinolinecarboxylates
Authors: Mitrofanov A. Yu. , Kalugin D. A , Beletskaya I. P
Published: April 2024

An efficient method has been developed for the synthesis of 4-trifluoromethyl-substituted quinolinecarboxylates by the gold(I)-catalyzed reaction of 2’-amino-2,2,2-trifluoroacetophenones with substituted propiolates.
Synthesis of 2-(3,5-diallyl-2,4,6-trioxo-1,3,5-triazinan-1-yl)ethyl-ureas and -carbamates
Authors: Kolyamshin O. A , Mitrasov Yu. N. , Danilov V. A , Kuz'min M. V , Ivanova K. Yu.
Published: April 2024

The interaction of 1-(2-aminoethyl)-3,5-diallyl-2,4,6-trioxo-1,3,5-triazinan with phenylisocyanate and 1,6-hexamethylene diisocyanate gave new 3,5-diallyl-and 3,3',5,5'-tetraallylsubstituted isocyanurates containing one and two carbamide groups in their composition. The reaction of 1-(2-hydroxyethyl)-3,5-diallyl-2,4,6-trioxo-1,3,5-triazinan with phenyl isocyanate synthesized 1,3,5-triazinan-1-yl)ethyl-N-phenylcarbamate, and by alkylation of the sodium salt of 3,5-diallyl-2,4,6-trioxo-1,3,5-triazine bis(2-chloroethyl)hexane -1,6-diyldicarbamate was used to prepare bis-[2-(3,5-diallyl-2,4,6-trioxo-1,3,5-triazinan-1-yl)ethyl]hexane-1,6-diyldicarbamate. The physical and spectral properties of the obtained 3,5-di- and 3,3',5,5'-tetraallyl isocyanurates were studied.
Heterocyclisation of N-(2-cycloalk-1-en-1-yl-6-methylphenyl)-N-(2-hydroxyethyl)-4-methylbenzenesulfonamides to benzoxazocines
Authors: Gataullin R. R
Published: April 2024

The article cover the results of a study on the synthesis of benzoxazocines condensed with cycloalkenes. By reacting the corresponding N -tosyl-2-(1-cycloalken-1-yl)anilines with 2-bromoethyl ester of acetic acid, the products of substitution of bromine for the arylamide group were synthesized. The resulting esters were converted by alkaline hydrolysis into N -(2-cycloalk-1-en-1-yl-6-methylphenyl)- N -(2-hydroxyethyl)-4-(methylbenzene)sulfonamides. The interaction of these amides with molecular bromine gives benzo[ e ]cycloalka[ g ][1,4]oxazocine N -tosylates with predominant a R *, R *-stereochemistry, which in solution slowly turn into a S *, R *-atropisomers reaching a ratio of 2.7:1 in the case of cyclohexenyl and 1.4:1 in the case of cyclopentenyl homologues.
Synthesis and optical properties of π-conjucated azulenes
Authors: Merkhatuly N. , Iskanderov A. N , Zhokizhanova S. K , Kokibasova G. T
Published: April 2024

Knoevenagel condensation of azulenyl ketones with malononitrile synthesized π-conjugated 1-mono- and 1,3-bis(phenyl-dicyanovinyl)azulenes, and 1-mono- and 1,3-biphenylazulenes were obtained by the Kumada cross-coupling ofbromazulenes with PhMgBr. The electronic spectra of dicyanovinylatedazulenes showed intense absorption bands of intramolecular charge transfer in the visible region, as well as significant bathochromic shifts of the absorption band maxima for phenylazulenes.
Synthesis of triethylene glycol-substituted phenylterpyridine with a terminal aurophilic group and its coordination compound with Rh(III) for adsorption on the gold surface
Authors: Salimova I. O , Moiseeva A. A , Zyk N. V , Beloglazkina E. K
Published: April 2024

A method has been developed for the preparation of a conjugate of 4-substituted phenylterpyridine and lipoic acid with a triethylene glycol linker between the terpyridine and sulfur-containing fragments. A coordination compound of the obtained terpyridine with Rh(III) have been synthesized. The ability of the resulting ligand and rhodium complex to be chemisorbed on the surface of gold electrodes with the formation of an Au-S bond have been shown using the cyclic voltammetry.
Synthesis of new diazamantane derivatives, containing the phenylimide grouping in 2 position
Authors: Kocharov S. L , Gevorkyan K. A , Arutyunyan A. D , Galstyan M. V , Panosyan G. A , Avakimyan J. A , Stepanyan G. M
Published: April 2024

By interaction between few recently prepared 2,5,7-substituted 6-keto(hydroxy)-1,3-diazaadamantanes and anhydrides of different dicarbonic acids 15 new diazaadamantane analoques, containing phthalimide or succinimide fragments have been prepared.Target compounds were tested for antibacterial activity.
Problems of synthesis of mercapto derivatives from corresponding hydroxy derivatives of polyphenylenes
Authors: Finko A. V , Saakian A. S , Bezborodov V. S , Mikhalyonok S. G , Talroze R. V
Published: April 2024

In order to study the possibility of creating new anisotropic nanocomposites based on organic molecules containing mercapto groups for specific interaction with nanoparticles, the possibility of converting hydroxy derivatives of polyphenylenes into the corresponding thiols was studied.
Synthesis of 1-allyl-N,N-dialkyl-, 1-allyl-pentamethyleneand 1-allyl-spiro-4-phenyl-3а,4-dihydrobenzo[f]isoindoliniumbromides on the basis of base-catalyzed intramolecular cyclization
Authors: Chukhadzhyan E. O , Ayrapetyan L. V , Mkrtchyan A. S , Aloyan A. K , Panosyan G. A
Published: April 2024

Base-catalyzed intramolecular cyclization of N , N -dimethyl-, N , N -diethyl-, pentamethylene- and spiro[1-allyl](3-phenylprop-2-ynyl)(3-phenylprop-2-enyl)ammonium bromides were synthesized 1-allyl- N , N -dialkyl-, 1-allyl-pentamethylene- and 1-allyl-spiro-4-phenyl-3а,4-dihydrobenzo[f]isoindolinium bromides in high yields. Along with cyclizationalso took place 8-10% side reactions.
New synthesis of cycloalca[с]nicotinoamide and nitrile derivatives
Authors: Dyachenko I. V , Dyachenko V. D , Dorovatovskii P. V , Khrustalev V. N , Abakarov G. M , Nenajdenko V. G
Published: April 2024

Nitriles and amide of nicotinic acid were synthesized by Knoevenagel reactions, nucleophilic vinyl substitution (SNVin), and alkylation. The structure of (1-amino-5-phenyl-5,6,7,8-tetrahydrothieno[2,3- c ]isoquinolin-2-yl)(phenyl)methanone was studied by X-ray analysis.
Synthesis of 4-isopropyl derivatives of levoglucosenone
Authors: Faizullina L. Kh. , Galimova Yu. S. , Ryabova A. S , Galimzyanova N. F , Valeev F. A
Published: April 2024

The synthesis of 4-hydroxyisopropyl derivative of levoglucosenone has been developed and its dehydration and reduction, including enzymatic reduction to the unsaturated and 2S-hydroxy derivative, have been carried out. The fungicidal activity of the unsaturated derivative against the microscopic fungi Rhizoctonia solani was found, similar to the of l-menton.
Urea and thiourea derivatives in the synthesis of hexaoxazadispiroalkane carboxamides
Authors: Makhmudiyarova N. N , Ishmukhametova I. R
Published: April 2024

An efficient method for the synthesis of di(6,7,13,14,18,19-hexaoxa-16-azadispiro[4.2.48.75]nonadecan-16-yl)methane(thi)ones and N -substituted hexaoxaazadispiroalkanecarboxamides by the reaction of 3,6-di(spiroalkane)substituted heptaoxacycloundecanes with thiourea and urea derivatives (urea, 1,1-dimethylurea, 1-phenylurea, 1-allylurea) with the participation of Sm(NO3)3·6H2O as a catalyst.
Synthesis of new fluorene-containing 9-azabicyclo[4.2.1]nona-2,4,7-trienes [6π+2π]-cycloaddition of alkynes to N-carbofluorenylmethoxyazepine
Authors: Kadikova G. N , D'yakonov V. A
Published: April 2024

Catalytic [6π+2π]-cycloaddition of terminal alkynes to N -carbofluorenylmethoxyazepine under the action of a three-component catalytic system Co(acac)2(dppe)/Zn/ZnI2 was performed for the first time to obtain previously undescribed and promising 9-azabicyclo[4.2.1]nona-2,4,7-trienes (in 79-92% yields) containing a fluorene substituent.
Mass Spectra of New Heterocycles: XXVI. Electron Impact and Chemical Ionization Study of N-[5-Amino-2-thienyl]- and N-[2-(Methylsulfanyl)-1,3-thiazol-5-yl]isothioureas
Authors: Klyba L. V , Sanzheeva E. R , Nedolya N. A , Tarasova O. A
Published: April 2024

The behavior of a representative series of previously unknown N -(5-amino-2-thienyl)- and N -[2-(methylsulfanyl)-1,3-thiazol-5-yl]isothioureas under electron ionization (70 eV) has been studied for the first time. 2-Thienylisothioureas form a fairly stable molecular ion ( I rel 11-25%), whereas there are no peaks of molecular ions in the mass spectra of 1,3-thiazolylisothioureas. The common direction of the decay of the molecular ion of 2-thienyl- and 1,3-thiazolylisothiourea is the breaking of the C-N bond in the isothiourea fragment with the localization of the charge on the imine nitrogen atom and the formation of the ion [R3SC≡NR2]+ ( I rel 34-100%), and for thienyl derivatives also the ion [ M - R3SC=NR2]+ (with the localization of the charge on the amine nitrogen atom). Moreover, the last ion is the main one ( I rel 91-100%). Peaks of [ M - MeSCN]+• and [MeSCS]+ ions have also been identified in the spectra of 1,3-thiazolylisothioureas, the appearance of which is associated with the decay of the thiazole cycle in a molecular ion. In addition, unlike 2-thienylisothioureas, for the studied 1,3-thiazolylisothioureas, there is a break in the Chet-N bond with the localization of the charge on the thiazole-containing fragment.
Unusual Transformations of Allylsilanes in the Reactionwith N,N-Dichloroarenesulfonamides
Authors: Ushakova I. V , Shainyan B. A
Published: April 2024

The reaction of dimethyl(chloromethyl)allylsilane and dimethyl- and diphenyl(diallyl)silanes with N , N -dichloroarenesulfonamides was studied. Due to the presence of active chlorine, in the reaction with monoallylsilane the products of chloroamination were obtained, whereas with diallylsilanes 4-chloro-1-sulfonyl-1,2-azasilolidines and 1-[(4-chlorophenyl)sulfonyl]-5,5-diphenyl-1,4,5,6-tetrahydro-1,5-azasilocine were formed in moderate yields.
Synthesis of 4,6-disubstituted bicyclo[3.3.1]nona-3,6-dien-2-ones
Authors: Mikhalyonok S. G , Bezborodov V. S , Kuz'menok N. M , Savelyev A. I , Arol A. S
Published: April 2024

Bicyclo[3.3.1]nonane system is an important structural motif observed in a diverse natural products. Here, we report a concise synthetic route exploiting aldol condensation reactions for construction bicyclo[3.3.1]nonane ring system. Our strategy employes cyclohex-2-enones bearing another carbonyl group in side chain as key structural unit. The reaction showed good results for substrates bearing electron-donating groups in aromatic substituents. Overall, the described synthesis of bicyclo[3.3.1]nona-3,6-dien-2-ones required 2 steps and only 2 building blocks (such as Mannich base and acetoacetic ester) to access desired bicyclic system.
Three-component synthesis of benzhydrazide-based spiropyrazolines
Authors: Meshcheryakova A. A. , Neumoina K. S. , Sorokin V. V.
Published: April 2024

New 3-Amino-1,2-diazaspiro[4.5]non-3-ene-4-carbonitriles, 3-amino-1,2-diazaspiro[4.5]deca-3-ene-4-carbonitriles were obtained by the three-component condensation of malononitrile, cycloalkanones and benzhydrazides. The structures of the synthesized compounds were established by spectroscopic methods.
Synthesis and study of the hemostatic activity of substituted 5-oxo-1-cyano-3-{(3-cyano-4,5,6,7tetrahydrobenzo[b]thiophen-2-yl)amino{penta-1,3-dien-2-olate potassium
Authors: Lipin D. V. , Kozlov D. A. , Shadrin V. M. , Parkoma K. Yu. , Starkov A. V. , Shipilovskikh D. A. , Pulina N. A. , Shipilovskikh S. A.
Published: April 2024

New substituted substituted Potassium 5-oxo-1-cyano-3-{(3-cyano-4,5,6,7-tetrahydrobenzo[ b ]thiophen-2-yl)amino}penta-1,3-dien-2-olates. The structure of the obtained compounds was confirmed by 1Н, 13С NMR spectroscopy and elemental analysis. The anticoagulant activity of the synthesized compounds was studied.
Pyridoxinium salts of O-monoterpenyl aryldithiophosphonic acids
Authors: Nizamov I. S. , Yakovlev A. A. , Nizamov I. D. , Mavrov Ye. A. , Batyeva E. S. , Cherkasov R. A.
Published: April 2024

Aryldithiophosphonic acids obtained from monoterpenyl alcohols react with pyridoxine and seven-membered pyridoxine acetonide to form pyridoxinium arylphosphonodithioates possessed high antibacterial activity against Bacillus cereus .
A new method preparation of trimethylsilyl ethers of III-valence phosphorus
Authors: Morgalyuk V. P. , Strelkova T. S. , Takazova R. U. , Buyanovskaya A. G. , Brel V. K.
Published: April 2024

By the interaction of hydrophosphoryl compounds of various structures with hexamethyldisilazane at 20°C and in the presence of ZnSO4 and diethylamine, trimethylsilyl esters of acids of III-valent phosphorus were synthesized in high yields (89-94%). The reaction is completed in 4 hours, does not require the use of specially prepared solvents and an inert atmosphere, and can be proposed as a new synthetically useful and easy-to-perform method for the synthesis of trimethylsilyl esters of acids of III-valent phosphorus.
Synthesis and discovery of a water-soluble ureid of galodif with succinic acid
Authors: Kuksenok V. Yu. , Cui Y. , Shtrykova V. V. , Filimonov V. D. , Shushpanova T. V.
Published: April 2024

For the first time, a new acyl ureide of the anticonvulsant and anti-alcohol drug galodif (3-chlorobenzhydryl urea) with succinic acid was obtained and studied. The synthesis was carried out by the acylation of galodif with succinic anhydride in presence of certain acids. Unlike galodif, which is practically insoluble in water, the resulting benzhydryl ureide is soluble in aqueous media and can potentially exhibit greater bioavailability and can be used as a liquid dosage form and prodrug with prolonged action.
Double Mirozoki-Heck arylation of terminal alkenes using “ligand-free” pd catalytic systems
Authors: Kurokhtina A. A , Larina E. V , Lagoda N. A , Grigoryeva T. A , Schmidt A. F
Published: April 2024

The results of one-pot consecutive double arylation of terminal alkenes with aryl halides leading to three-substituted alkenes are presented. The advantages of the method when comparing with existing analogues are the combination of low reactive but available aryl bromides and aryl chlorides and «ligand-free» catalytic systems based on Pd(II) salt.