Synthesis of Schiff bases on the basis of the isosteviol terpenoid

The transformation of the carboxy and keto groups of the isosteviol (ent-16-ketobeyeran-19-oic acid) diterpenoid was used to synthesize its new nitrogen-containing derivatives, including Schiff bases by the C⁴ and C¹⁶ atoms of the isosteviol frame. The structure of the resulting compounds was established by X-ray diffraction.     

Kinetics of the reactions of [Chloro(phenyl)arsanyl]acetic acid with bromo- and iodoacetic acids

Quternization of [chloro(phenyl)arsanyl]acetic acid with bromo- and iodoacetic acids in aqueous alkali follows S_N2 mechanism and is accompanied by alkaline hydrolysis of haloacetic acids. The rate constants and thermodynamic parameters of the process were determined     

Mass spectra of isosteviol derivatives: I. Fragmentation of isosteviol derivatives having a Schiff base fragment on C<Superscript>4</Superscript> under electron impact

The main fragmentation pathways of the molecular ions of isosteviol (ent-16-oxobeyeran-19-oic acid) derivatives having a Schiff base fragment on C⁴ under electron impact include expulsion of CO molecule and methyl radical, cleavage of the C⁴-N bond with proton migration to the nitrogen atom, and dissociation of come bonds in the A and B rings of the tetracyclic skeleton.     

Synthesis of phosphorylated derivatives of isatin with sterically hindered phenol fragments

The synthesis of N-[dimethoxyphosphoryl-(3,5-di-tert-butyl-4-hydroxyphenyl)] methylisatins has been performed by the addition of isatin and 5-butylisatin to the double bond of dimethyl-(3,5-di-tert-butyl-4-oxo-2,5-cyclohexadienylidene)methylphosphonate. Subsequent functionalization of the compounds synthesized with thiosemicarbazide hydrochloride, 3-(3′,5′-di-tert-butyl-4′-hydroxyphenyl)propionic acid hydrazide, and isonicotinic acid. Hydrazide gave isatin derivatives containing several pharmacophore fragments. Each of them has the ability to the increase the antioxidant and biological activities of these compounds.     

The Strong Thirteen Spheres Problem

The thirteen spheres problem asks if 13 equal-size non-overlapping spheres in three dimensions can simultaneously touch another sphere of the same size. This problem was the subject of the famous discussion between Isaac Newton and David Gregory in 1694. The problem was solved by Schütte and van der Waerden only in 1953. A natural extension of this problem is the strong thirteen-sphere problem (or the Tammes problem for 13 points), which calls for finding the maximum radius of and an arrangement for 13 equal-size non-overlapping spheres touching the unit sphere. In this paper, we give a solution of this long-standing open problem in geometry. Our computer-assisted proof is based on an enumeration of irreducible graphs.     

The Di Vecchia-Ravndal superparticle theory

We propose for the Di Vecchia-Ravndal superparticle a transition procedure from Grassmann variables, in which the dynamics are formulated, to observable values. We have found expressions for the density function and the corresponding quantum mechanical density matrix.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 5–7, July, 1991.     

Quadratic torsion-metric model consistent with then-dimensional gravitational theories of einstein and weyl

We examine a gauge model with a Lagrangian, quadratic in the Riemann-Cardan curvature, without a separate Hilbert Lagrangian. It is argued that torsions must be massive particles, the torsion field does not act on world fields, and the orthogonal components of the contorsion tensor must not vary with variations of the metric. It is shown that a new torsion-metric interaction arises in this case, which generates the gravitational theories of Einstein and Weyl. Kazan State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 21–25, June, 1998.     

1,3,2(1,4,2)-Dioxaphosphepins annelated with naphthalene fragment: Synthesis and steric structure

Reaction of hexafluoroacetone and chloral with 2-R-naphtho-1,3,2-dioxaphosphorin-4-ones yields 2-R-2,5-dioxo-4,4-bis(trifluoromethyl)naphthol-1,3,2-and 2-R-2,5-dioxo-3-trichloromethylnaphtho-1,4,2λ⁵-dioxaphosphepins. Hydrolysis of the fluorophosphepins gives naphthyl-substituted fluorinated hydroxy ketones. The steric structure of the dioxaphosphepins and some fluorinated ketones was confirmed by single crystal X-ray diffraction. A competition between the π-π and halogen-halogen interactions and hydrogen bonds of classic type in the formation of crystal packing and supramolecular structure was revealed.     

Alkylation of the isosteviol terpenoid and its oxime with dibromoalkanes in the KOH-DMSO system

The reaction of 16-hydroximinoisosteviol with dihaloalkanes in the KOH-DMSO results in coupling of two isosteviol carcasses by the carboxy groups. The same products were previously synthesized by hydroximination of isosteviol diesters.