Conformational study of N-vinyl-2-isopropyl- and N-vinyl-2-cyclopropylpyrroles by1H and13C NMR

In N-vinyl-2-isopropylpyrrole the isopropyl group is in a conformation with the CH₃ group in an anti position to the vinyl group. On introducing a substituent at the 3 position of the ring the isopropyl group passes into a gauche and (or) a syn conformation, leading to an increase in the dihedral angle between the plane of the vinyl group and the pyrrole ring. In N-vinyl-2-cyclo-propylpyrrole the cyclopropyl group is 80% in the gauche form, which is attributed to the repulsion between the electrons of the -shells of the cyclopropyl and pyrrole fragments.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1031–1038, May, 1991.     

Dipole moments and molecular conformations of acetylpyrimidines

By comparing experimentally determined dipole moments with those derived from vector-addition and semiempirical computation using MNDO and AM 1 approximations the conformations of 4- and 5-acetylpyrimidines were found to be close to planar, while that of 2-acetylpyrimidine exhibited a torsion angle of 90°.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1387–1390, October, 1992.     

Synthesis of isomeric aminophenylbipyrimidines and study of the liquid crystalline properties of anils structurally related to aminophenylpyrimidines

5-Amino-2,5bipyrimidines and bis-(5-aminopyrimidinyl-2)-p-phenylenes have been synthesized as well as isomeric bis-(p-aminophenyl)pyrimidines. From these, substituted benzylidenamino derivatives have been prepared and their liquid crystalline properties studied.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 509–513, April, 1993.     

Synthesis of schiff bases of 2-substituted 5-aminopyrimidines and their mesomorphic properties

Schiff bases of 2-substituted 5-aminopyrimidines were synthesized, and their liquid-crystal and dielectric properties were investigated. It is shown that narrow ranges of the existence of meso phases and a greater (as compared with benzyl-ideneanilines) tendency for the development of a smectic state are characteristic for 2-alkoxy-, 2-alkyl-, and 2-cyano-5-arylideneaminopyrimides. The introduction of an aryl substituent into the 2 position of the pyrimidine ring gives rise to a pronounced increase in the thermostability of the meso phase and significantly increases the range of its existence. The use of groups with higher dipole moments as terminal groups leads to the production of compounds with high positive dielectric anisotropies.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1545–1552, November, 1982.     

N-Silatranylmethyl Derivatives of Pyrrole,Indole, and Carbazole

Organosilicon derivatives of pyrrole, indole, carbazole, and 2-methylindole containing (MeO)₃SiCH₂, Et₃SiCH₂, or N(CH₂CH₂O)₃SiCH₂ group on the nitrogen atom were synthesized. Their structure and stereoelectronic parameters were studied by X-ray diffraction, ¹H, ^{1 3}C, ^{1 5}N, and ^{2 9}Si NMR, IR and UV spectroscopy, and dielcometry, as well as by quantum-chemical calculations.     

Pyrimidines. 70. Relative reactivities of the chlorine atoms of 2,2′,4-trichloro-4′,5-dipyrimidinyl in its reaction with piperidine

2,2,4-Trichloro-6-phenyl-4,5-dipyrimidinyl, for which nucleophilic substitution with piperdine under various conditions was studied, was obtained from 2,2,4-trioxo-6-phenyl-1, 1,2,2,3,4-hexahydro-4,5-dipyrimidinyl. It is shown that there is an appreciable difference in the rates of substitution of the first, second, and third chlorine atoms, and this made it possible to obtain reaction products that contain one, two, and three piperidino groups. The chlorine atom in the 4 position is replaced initially, after which the chlorine atom in the 2 position undergoes substitution. The structures of the compounds were proved by chemical transformations and analysis of the PMR spectra.See [1] for communication 69.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 821–826, June, 1979.     

Pyrroles from ketoximes and acetylene 8. Synthesis of 4,5,6,7-tetrahydroindole and its 1-vinyl derivative

4,5,6,7-Tetrahydroindole or 1-vinyl-4,5,6,7-tetrahydroindole was obtained in 81 and 93% yields, respectively, by reaction of cyclohexanone oxime with acetylene at 90–140C in the presence of alkali metal hydroxides or alkoxides in dimethyl sulfoxide (DMSO) or mixtures of DMSO with low-polarity or nonpolar solvents. The reaction is effective both in an autoclave (initial pressure 8–16 gage atm) and at atmospheric pressure.See [1] for communication 7.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 197–199, February, 1979.     

Polycyclic rod-shaped azo dyes based on aminophenylpyrimidines

We have synthesized rod-shaped tricyclic monoazo and bisazo dyes based on amino derivatives of arylpyrimidines and N,N-dialkylanilines orp-nitroso-N,N-dialkylanilines. We have shown that the process of azo coupling of the diazonium salt obtained from 2,5-bis(p-arninophenyl)pyritnidine is accompanied by dediazoniation, with substitution of the diazonium group by hydrogen or an aryl group. The monoazo dyes obtained display mesomorphic properties which are absent in the bisazo dyes.Novosibirsk Institute of Organic Chemistry, Siberian Division of the Russian Academy of Sciences, Novosibirsk 630090. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 693–702, May, 1996. Original article submitted January 25, 1996.     

Synthesis of 2-benzoylethynylpyrroles by cross coupling of 2-arylpyrroles with 1-benzoyl-2-bromoacetylene over aluminum oxide

Cross coupling of 2-arylpyrrole with benzoylbromoacetylene over aluminum oxide at room temperature gave 45–94% of 2-(benzoylethynyl)-5-arylpyrroles. Intermediate 2-(2-benzoyl-1-bromoethenyl)-5-arylpyrroles were isolated in up to 19% yield. The reaction was accompanied by formation of less than 5% of adducts of the initial pyrroles with the cross-coupling products, 2-benzoyl-1,1-bis(5-arylpyrrol-2-yl)ethenes.     

Synthesis of Functionally-substituted Pyrrolothiazolidines from Pyrrole-2-carbodithioates, CH-acids, and Haloacetylenes

Functionally substituted pyrrolothiazolidines have been synthesized by the sequential treatment of pyrrole-2-carbodithioates with methylene-reactive nitriles and haloacetylenes in a KOH-DMSO system.