Solvatochromism of Heteroaromatic Compounds: XVII. Effect of Aprotic Inert Solvents on the Structure of 2-(2,2-Dicyanovinyl-1-methylthio)-5-methylpyrrole

The effect of aprotic inert media on the conformational structure of 2-(2,2-dicyanovinyl-1-methylthio)-5-methylpyrrole was studied by UV, NMR, and IR spectroscopy. Chloroform and less polar solvents stabilize only one of the four conformers. In more polar media, there is a dynamic equilibrium between all the possible conformers of the title compound. The state of the equilibrium depends both on the solvent and on the temperature.     

Pyrimidines

A new method was developed for the preparation of 1,3-diarylbenzo[f]quinazolines by condensation of-naphthylamine, an aromatic aldehyde, and ammonia and subsequent dehydrogenation of the initially formed dihydro derivatives.See [1] for communication LIV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 100–104, January, 1978.     

Pyrimidines

It is shown that the reaction of benzalbisurea with 3-amino-5-hydroxy-1-R-pyrazoles gives 1-R-dipyrazolo[3,4-b:4,3-e]pyridine (R=CH₃) or a spiro(pyrazole-4,5-pyrimidine) derivative (R=C₆H₅). Similar reactions of benzalbisurea with 3-hydroxy-5-amino-1-methylpyrazole give 2-methyldipyrazole[3,4-b:4,3-e]pyridine or substituted tetrahydropyrazolo[3,4-d] pyrimidine. Only the corresponding dipyrazolo[3,4-b:4,3-e]pyridines are formed in the reaction of 1-methylhydroxyaminopyrazoles with methylenebisurea.See [1] for communication XXXIX.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 823–827, June, 1974.     

Chemoselective noncatalytic addition of secondary phosphine chalcogenides to citral

Addition of secondary phosphine oxides, phosphine sulfides and phosphine selenides to 3,7-dimethyl-2,6-octadienal (citral) (48–50°C, THF, argon) proceeds exclusively to the aldehyde group giving rise to new polyfunctional tertiary phosphine chalcogenides with diene and hydroxyl moieties in high preparative yield (up to 80%).     

Azirines in reactions involving the formation of a pyrrole ring (review)

The literature data on the synthesis of pyrroles from azirines are correlated in this review. The following processes are examined: the thermolysis and photolysis of azirines with aromatic radicals and double bonds, the rearrangement of aryl- and vinylazirines under the influence of metal complexes, the cycloaddition of olefins, the cycloaddition of acetylenes, and reactions with CH acids.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1299–1312, October, 1986.     

Pyrroles from ketoximes and acetylene

On the basis of a comparative study and analysis of the chemical shifts in the ¹³C NMR spectra of 1-vinyl-2-arylpyrroles and 3-alkyl-1-vinyl-2-phenylpyrroles, as well as 2-phenyl- and 1-ethyl-2-phenylpyrroles, it was established that the effects of substituents in the investigated series are transmitted via a mechanism involving conjugation and induction; the conductivity and polarizability of the 2-arylpyrrole system increase when a vinyl group is introduced in the 1 position or, in the case of the 1-vinylpyrrole system, when a phenyl group is introduced in the 2 position; this is due to the increase in the degree of overall conjugation.See [1] for communication IV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 768–772, June, 1978.     

Modified copolymers of bifunctional vinyl ethers with methyl vinyl sulfide as active matrices of solid superbases

Reactive linear and crosslinked copolymers of diethylene glycol divinyl ether and ethylene glycol vinyl glycidyl ether with methyl vinyl sulfide have been synthesized in the presence of 2,2′-azobis(isobutyronitrile) (2%, 60 °C, 45–55 h) in ∼53% yield. The hydrolyzed at the residual vinyloxy and epoxy groups and oxidized at the methylthio groups copolymers upon treatment with KOH afford alkoxide (complex) and crown-like superbases. They are capable of catalyzing the acetone ethynylation, as well as the prototropic isomerization of methyl propargyl ether to allenyl methyl ether and vinylation of ethylene and diethylene glycols with acetylene.     

Hydrogen complexes of <Emphasis Type="Italic">O</Emphasis>-vinylacetoxime with trifluoroacetic acid

According to B3LYP/6-31G** calculations, the stable antiperi-, antiperiperiplanar and antiperi-, synperiperiplanar conformers of O-vinylacetoxime (1) form with trifluoroacetic acid strong H complexes of two types: with N···H-O and O···H-O hydrogen bonds. The former are more stable. Complexation changes N-O and C-O bond lengths in molecule 1, as well as mutual orientation of its vinyl and azomethine groups. The structural effect depends on the orientation of the H bond, which, in its turn, is determined by the nature of the electron-donor center. When the nitrogen atom of oxime 1 is involved in complex formation, the H bond lies in the molecular plane, whereas the H bond involving the oxygen atom is directed in parallel with its lone electron pair.     

The Properties of Strings Formed in the Homochiral Solutions of Trifluoroacetylated Amino Alcohols in Cyclohexane

The strings formed in the solutions of trifluoroacetylated amino alcohols in cyclohexane were studied. It was found that microscopic strings with the diameter d ～ 1 μm were woven from tightly coupled rigid submicroscopic strings with the diameter d ～ 0.1 μm in increments of >100 μm. Therefore, the compound strings are transparent, and they usually look like an unstructured cylinder. Microscopic strings can be tightly combined in strings to 60 μm in diameter. Submicroscopic strings are arranged almost parallel to the axis of a microscopic string. The microscopic string acts as a polarizer: it transmits light polarized across its axis and absorbs light polarized along the axis. The majority of these properties can be explained based on the assumption that a connection between the strings of all hierarchical levels in cyclohexane is stronger than that in solvents with different string morphology.     

Synthesis and mesomorphic properties oftrans-[1,4-bis(5-R-pyrimidin-2-yl]-cyclohexanes and 1,2-bis-(5-R-pyrimidin-2-yl)ethanes

New trans-bis(5-R-pyrimidin-2-yl)-1,4-cyclohexanes and-1,2-ethanes (R=C₇H₁₅, C₆H₄OR¹, where R¹=H, COCH₃, C₄H₉, C₅H₁₁, C₈H₁₇) have been synthesized. Only nematic mesophases are found from a study of their mesomorphic properties, except for bis[5-(4-octyloxyphenyl)- and-(4-acetoxyphenyl)pyrimidin-2-yl)-cyclohexanes, which also exhibit smectic properties.Novosibirsk Institute of Organic Chemistry of the Siberian Division of the Russian Academy of Sciences, Novosibirsk 630090, Russia; e-mail: benzol@nioch.nsc.ru. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 355–360, March, 1999.