Electrocatalytic multicomponent one-pot approach to tetrahydro-2′H,4H-spiro[benzofuran-2,5′-pyrimidine] scaffold

The new electrocatalytic multicomponent transformation has been found: the electrolysis of arylaldehydes, N,N′-dimethylbarbiturate, and cycloxehane-1,3-diones in alcohols in the presence of sodium bromide as a mediator in an undivided cell results in the formation of substituted unsymmetric spirobarbituric dihydrofurans in 62%–76% yields. The optimized reaction conditions and a mechanistic rationale for this electrocatalytic multicomponent transformation are presented. This new electrocatalytic process is a facile and efficient way to produce substituted unsymmetric spirobarbituric dihydrofurans containing both barbituric and 3,5,6,7-tetrahydro-1-benzofuran-4(2H)-one fragments, which are promising compounds for different biomedical applications, among them are anticonvulsants, anti-AIDS agents, and antiinflammatory remedies. The scaffold approach was employed to find a protein, which may be influenced by the synthesized compounds—human aldose reductase was proposed. It was shown by molecular docking studies that such a scaffold search is beneficial and tetrahydro-2′H,4H-spiro[benzofuran-2,5′-pyrimidines] used in this approach are promising for the development of novel aldose reductase inhibitors.     

Silver ion liquid-chromatographic mobility of plant diacylglycerols as a function of their composition and spatial arrangement

Coordination complexes of unsaturated rac-1,2-diacylglycerols (DAGs) with silver ions were separated by adsorption and reversed-phase TLC (silver ion TLC and silver ion RP-TLC, respectively). During silver ion TLC, silver ion complexes are formed by an indeterminate number of coordination centers of various nature and only at the adsorbent surface; separation of the complexes proceeds according to an adsorption mechanism, and there is an inverse exponential relationship between DAG unsaturation and their mobility. With silver ion RP-TLC, the complexes are formed only with double bonds, only in solution, and at a 1:1 ratio; the complexes are fractionated by lipophilic partitioning between two liquid phases, and the relationship between the unsaturation of DAGs and their mobility is a direct linear one. Nevertheless, in spite of all these differences, the use of both methods demonstrated that DAG species characterized by a coiled acyl configuration always greatly exceeded in polarity those with the same unsaturation, but with the configuration close to an extended one; in the former group, this excess amounted to two- to three-fold and 30-40% for silver ion TLC and silver ion RP-TLC, respectively. In addition, for both versions of silver ion LC, these two groups of species differ from each other quantitatively, but not qualitatively, in the pattern of the relationship between the unsaturation and mobility of DAG complexes. Thus, under all conditions of silver ion LC studied here, the polarity of DAG complexes and, therefore, their mobility are conditional not only on the number of double bonds, but also on their configuration.     

Dipole moments,Kerr constants,and structure of oxides of substituted norbornenes

The molar Kerr constants and dipole moments at infinite dilution in CCl₄ have been measured for these compounds and also for dicyclopentadiene dioxide and the oxides of ethylene, propylene, and tetramethylethylene. The dipole moment indicates an exo-oxide structure for endo-cyanonorbornene, and this fact is used with the Kerr constants for endo-cyanonorbornene and ethylene oxide to calculate the axes of the polarizability ellipsoid for the oxide ring: b₁ (along the symmetry axis), b₂ (in plane of ring), and b₃ (perpendicular to plane of ring). The Kerr constants for propylene and tetramethylethylene oxides have been used to determine the anisotropy in the polarizability of the C-C bond adjoining the oxide ring. The results demonstrate an exo mode of oxidation of all substituted norbornenes and an exo-exo structure for dicyclopentadiene dioxide.     

Three-dimensional structure of phosphorus-containing heterocycles

The three-dimensional structure of a number of 2-thiono-1,3,2-dioxaphosphorinanes was studied by means of dipole moments, the Kerr effect, and theoretical conformational analysis with P³¹ NMR data. 2,4-Dimethyl- and 2-chloro-2-thiono-1,3,2-dioxaphosphorinanes have the chair conformation with an equatorial thionophosphoryl group; the 2-methyl derivative exist as an equilibrium mixture of the axial and equatorial conformers with predominance of the former. The participation of the boat form in the conformational equilibrium was established for 2-chloro-4-methyl derivative.See [1] for communication I.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1464–1468, November, 1971.     

Application of13C NMR spectroscopy and of fab mass spectrometry in the investigation of the minor triterpenoids ofThalictrum minus

Five minor triterpenoids have been isolated from the chloroform-soluble fraction of a methanolic extract ofThalictrum minus by chromatography on silica gel: (I) — oleanolic acid; (II) — oleanolic acid 3-0--L-arabinopyranoside; (III) — oleanolic acid 3-0-[0--D-glucopyranosyl-(1 3)--L-arabinopyranoside]; (IV) — oleanolic acid 3-0-[0--L-rhamnopyranosyl(1 2)-0--D-glucopyranosyl-(1 3)--L-arabinopyranoside]; and (V) — oleanolic acid 28-0--D-glucopyranoside 3-0-[0--D-glucopyranosyl-(1 3)--L-arabinopyranoside]. This is the first time that any of the compounds isolated have been detected in plants of the genusThalictrum. The possibility has been shown of determining the structures of triterpene glycosides on the basis of¹³C NMR spectroscopy and FAB mass spectrometry without chemical transformations of the glycosides.Irkutsk Institute of Organic Chemistry, Siberian Branch, Academy of Sciences of the USSR. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 107–111, January–February, 1987.