Synthesis of new chiral mono-, di-, tri-, and tetraalkylglycolurils

Two general procedures were developed for the synthesis of chiral N-mono-, N, N′-di-, N, N′ N″-tri-, and N, N′, N″, N′″-tetraalkylglycolurils based on the reactions of 4,5-dihydroxy-imidazolidin-2-ones or glyoxal with one or two moles of alkylureas, respectively, by acid catalysis. The reactions of N-monoalkyl- and N, N′-dialkylureas with glyoxal proceed regioselectively. The mechanism of these reactions was suggested and partly confirmed by quantum-chemical calculations and experimental data. The enantiomeric separation of some chiral glycolurils by chiral-phase HPLC was carried out for the first time.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 680–692, March, 2005.     

Room temperature MgI2-catalyzed Friedel–Crafts reaction between electron-rich (het)arenes and ethyl glyoxylate

Magnesium iodide-catalyzed addition of electron-rich (het)arenes to ethyl glyoxylate proceeds at room temperature with high chemoselectivity to afford ethyl 2-(het)aryl- 2-hydroxyacetates in yields up to 95%.     

A Close-to-Aromatize Approach for the Late-Stage Functionalization through Ring Closing Metathesis

An efficient approach for the synthesis of monosubstituted aromatic compounds relying on a ring-closing metathesis followed by spontaneous 1,2-elimination is presented. The efficiency for late-stage functionalization is highlighted in various solvents (up to 920 TON). This approach is compatible with strained cycles and other multiple bonds in the substrate.     

Elastoplastic equilibrium of an isotropic strip with a circular hole under pure bending

The range of variation of external forces over which the plastic region in a bent strip develops from initiation to complete envelopment of a circular aperture is determined. A perturbation method is used to construct a solution for these interactions. Institute of Applied Mathematics and Mechanics, National Academy of Sciences of Ukraine, Donetsk. Translated from Teoreticheskaya i Prikladnaya Mekhnika, No. 30, pp. 105–111, 1999.     

On the depth of the storage access function

We consider the synthesis problem for the storage access function, which often appears as a component of integrated circuits and is also used in theoretical investigations. The precise value of the depth of the storage access function depending on n address variables, where 1 ⩽ n ⩽ 5 or n ⩾ 20, is established over the standard basis under the assumption that the conjunction and disjunction gates have the depth 1 and that the negation gates have the depth 0. For the rest of the values of n the upper and the lower bounds for the specified depth are proven.     

The two-dimensional strained elastoplastic state of an isotropic cylindrical pipe

Using the small-parameter method we construct a closed-form solution of the problem of the two-dimensional strained elastoplastic equilibrium of an isotropic cylindrical pipe subject to a constant internal pressure or external compression. We compare the solutions found taking account of the Hencky or Reiss relations. Bibliography: 3 titles. Translated fromTeoreticheskaya i Prikladnaya Mekhanika, No. 28, 1998, pp. 29–36.     

Some asymptotically optimal one-sided embeddings of trees of similar formulas into rectangular lattices

We consider the problem of optimally placing trees of formulas in rectangular lattices. We construct and study two types of these trees and corresponding ways of placing (embedding) them into such lattices. The first is based on perfect binary trees, while the second is based on special binary trees. For the second type of tree embeddings, we prove asymptotic optimality among the trees of all formulas similar to the initial formula of no greater depth.     

A study of internal heat transfer in nonuniform porous structures

The results of theoretical and experimental studies of heat transfer and pressure drop in nonuniform porous materials and systems are presented. In experiments, measurements were made of the air flow rate, inlet and outlet air pressures, and air and porous sample temperatures. Experimental determination of the heat transfer coefficient in porous structures is associated with certain difficulties. The problem of determining a temperature difference between coolant and porous skeleton is the most complex. As a rule, under laboratory conditions this difference is small and cannot be found with sufficient accuracy. In the present work, the method of determination of the internal heat transfer coefficient is based on solving the inverse unsteady heat transfer problem for porous structures. Using this approach, the heat transfer coefficient is calculated indirectly or on the basis of the porous material temperature variation over time.