Thermal tranformation of cardiac glycosides

The thermal transformations of cardiac glycosides in neutral alcoholic solutions have been investigated. The kinetics of their acidless hydrolysis at 100 and 142°C and the activation energy of the process have been studied. The possibility has been shown of the stepwise hydrolysis of natural trisdigitoxosides with the production of difficulty available mono- and bisdigitoxosides. The following were used as the objects of investigation: convallatoxin, glucostrophanthidin, cheirotoxin, desglucocheirotoxin, erycordin, erysimin, erysimoside, digitoxin, and cymarin.All-Union Scientific-Research Institute of Drug Chemistry and Technology, Kharkov. Kharkov State Pharmaceutical Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 62–64, January–February, 1991.     

Boron fluorides of cis- and trans-2-aryl-3-aroylaziridines

The reaction of boron trifluoride etherate with cis- and trans-2-aryl-3-aroylaziridines yields the respective complexes in high yield. According to PMR spectral data the methyl group of boron trifluoride trans-1-methyl-3-aroylaziridines is located in syn-position, and in the cis-aziridine complexes in anti-position, to the carbonyl group.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1047–1049, August, 1987.     

Reaction of 1-alkyl-2-aryl-3-(2-methyl-2,3-epoxypropionyl)aziridines with boron trifluoride etherate in methanol

The reaction of boron trifluoride etherate in methanol with trans-1-methyl(ethyl)-or cis-1-cyclohexyl-2-aryl-3-(2-methyl-2,3-epoxypropionyl)aziridines leads to the formation of the corresponding boron fluoride complexes on the nitrogen atom of the aziridine ring. Reaction with trans-1-cyclohexyl-2-phenyl-3-(2-methyl-2,3-epoxypropionyl)aziridines occurs with stereospecific opening of the aziridine ring to give diastereomeric 2-methyl-5-methoxy-5-phenyl-4-cyclohexylamino-1,2-epoxypen-tan-3-ones, as well as products from the opening of the epoxide and aziridine rings — tetrahydrofuranones and tetrahydropyranones.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 596–600, May, 1986.     

Synthesis and crystal structure of 3,10-dimethyl-10H-dibenzo[b,e]iodinium tetrafluoroborate

The crystal and molecular structures of a chiral cyclic iodonium salt, namely, 3,10-dimethyl-10H-dibenzo[b,e]iodinium tetrafluoroborate, is solved by the direct method (a = 20.678(5) Å, b = 20.738(5) Å, c = 8.408(2) Å, γ =120.404(5)° Z = 4, sp. gr. P2₁/b). The crystals of the title compound consist of the iodonium cations and the BF ₄ ^? anions. The benzene rings A and B of the cations are planar. The angles between these rings are 56.1(4)° and 58.3(4)° in two independent molecules, and the rings are virtually coplanar with the corresponding halves of the central heterocycle C adopting the I,C(3)-boat conformation. The structural units are packed in the crystal so that each I atom forms short contacts with the fluorine atoms of two independent anions.     

Low-temperature far-infrared ellipsometry of convergent beam

Development of an ellipsometry to the case of a coherent far infrared irradiation, low temperatures and small samples is described, including a decision of the direct and inverse problems of the convergent beam ellipsometry for an arbitrary wavelength, measurement technique and a compensating orientation of cryostat windows. Experimental results are presented: for a gold film and UBe₁₃ single crystal at room temperature (=119m), temperature dependencies of the complex dielectric function of SrTiO₃ (=119, 84 and 28m) and of YBa₂Cu₃O_7– ceramic (A=119m).     

Synthesis of methyl -substituted 4-amino methyl-4-butanolides and 5 -hydroxy-2-piperidones

Esters of 5-amino-4-hydroxy-3-methylvaleric acids, which exist as pairs of diastereomers and are readily converted to the corresponding methyl-substituted 4-aminomethyl-4-butanolides or 5-hydroxy-2-piperidones, are obtained by reaction of esters of 3-methyl-4, 5-epoxy-2-pentenoic acid with amines and subsequent hydrogenation of the resulting esters of 5-amino-4-hydroxy-3-methyl-2-pentenoic acids.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 594–598, May, 1975.     

Existence and stability of a stationary solution of the system of diffusion equations in a medium with discontinuous characteristics under various quasimonotonicity conditions

Theoretical and Mathematical Physics - Asymptotic analysis is used to study the existence, local uniqueness, and asymptotic stability in the sense of Lyapunov of a solution of a one-dimensional...     

Oscillations of a Prismatic Rod

Equations are obtained for the longitudinal and transverse oscillations of a prismatic rod that differ from the standard equations of structural mechanics (strength of materials). The difference lies both in the appearance of new terms in the equations of motion corresponding to the Timoshenko theory, and in a refinement of the boundary conditions and the conditions on the rigidity of the rod for transverse oscillations. The oscillations of a vertical cantilevered rod when its base moves horizontally from a state of rest are examined and a comparison is made with the classical theory of transverse (bending) oscillations of prismatic rods.