gem-Bromochlorospiropentane reactivity toward methyllithium: an unusual carbenoid rearrangement

A skeletal carbenoid rearrangement of the gem-bromochlorospiropentanes in the presence of methyllithium has been studied. The synthetic and mechanistic aspects of this rearrangement as well as the influence of the halogen atom nature on the reaction pathway are discussed.     

Crystal and molecular structures of two sulfonium ylides: Influence of secondary S...O interactions on the molecular conformation and packing

Results are reported of an x-ray structure study of two sulfonium ylides formed by reaction of dimethylacetylenedicarboxylate with DMSO. It is demonstrated that one of these forms inter- and the other intramolecular secondary S...O interactions. In the first case they affect the molecular packing in the crystal; in the second, the molecular conformation.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 81–87, January, 1991.The authors thank V. A. Palyulin for calculating the geometry of the cyclic fragment using the Kramer-Pople method.     

New aspects of nitrosation of arylcyclopropanes: nitrosation of phenylcyclopropanes with bulky alkyl substituents in the small ring

It has been shown for the first time that nitrosation of phenylcyclopropanes with bulky alkyl substituents in the small ring proceeds predominantly with attack of the nitrosonium cation on the benzyl carbon atom of the cyclopropane ring with intermediate formation of an alkyl carbocation. In addition to isoxazolines, 1,2-oxazines and Δ¹-pyrroline N-oxide are formed, formation of the latter is preceded by skeletal rearrangement. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, 1566-1575, October, 2008.     

Molecular design of heterocycles. I. Recyclization graphs and structural hierarchy of the transformations of heterocycles

A new method for modeling the processes involved in the transformation of the ring of heterocyclic systems by means of recyclization graphs, the vertexes and ribs of which correspond only to the atoms and skeletal bonds that enter into the starting or final heteroring, is proposed. An analysis of the structures of such graphs and the use of various types of labels for the ribs and vertexes make it possible for the first time to construct a convenient and flexible hierarchy of recyclizations from the principle of the structural similarity in their recyclization graphs. The effectiveness of the approach is illustrated by examples of the classification of known interconversions of azoles and azines and by the prediction of new recyclizations.Plenary paper presented at the 5th All-Union Conference on the Chemistry of Nitrogen-Containing Heterocyclic Compounds, Chernogolovka, October 22–25, 1991.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 808–828, June, 1992.     

Experimental–Theoretical Technique for Determining the Equation-of-State Parameters for Soils

This paper considers an experimental–theoretical technique for determining pressure–strain curves and curves of yield strength versus pressure for soils based on disagreement between data of physical and numerical modeling of wave processes in a system of split Hopkinson bars with a soil sample in a holder. A convergent iterative procedure was developed to refine the equation-of-state parameters of soils obtained by the Kolsky method. The error of the technique is analyzed, the role of friction and the coefficient of sliding friction between the soil and the deformed holder.