E. Yu. Shmidt

2-Arylazo-1 -vinylpyrroles : Free-Radical Polymerization and Copolymerization

2-Arylazo-1-vinylpyrroles (a new group of azo dyes of the pyrrole series) are polymerized under heating (80°C) without initiators and in the presence of AIBN to form intensely colored paramagnetic and conducting polymers with a yield of 92%. By the example of the thermal copolymerization with 1-vinylpyrrolidone, it has been shown that 2-arylazo-1-vinylpyrroles may simultaneously play the roles of initiators and comonomers.

Selective synthesis of 1-vinylpyrroles directly from ketones and acetylene: Modification of trofimov reaction

Consecutive treatment of ketones with a system NH2OH·HCl-NaHCO3-DMSO and acetylene excess in the presence of KOH (100–120°C, initial acetylene pressure 12–15 at) led to a selective formation of 2-and 2,3-substituted 1-vinylpyrroles in 51–79% yields. Ketones of aliphatic, cycloaliphatic, aromatic, heteroaromatic, and tetrahydronaphthalene series were involved into the reaction.

Improved synthesis of tertiary propargyl alcohols by the Favorskii reaction of alkyl aryl (hetaryl) ketones with acetylene

Alkyl aryl (hetaryl) ketones react with acetylene under atmospheric pressure in the superbasic system KOH-EtOH-H2O-DMSO at 10–15°C (2 h) to give the corresponding tertiary propargyl alcohols in up to 91% yield. The procedure requires no large excess of KOH and low-boiling inflammable solvents, produces few wastes, and is safe and convenient on the laboratory scale; there are no limitations for its large-scale application.

Electrophilic addition of alcohols to 1-vinyl-2-phenylazopyrroles and unexpected formation of 2-methylquinoline

Abstract1-Vinyl-2-phenylazopyrroles react with alcohols in the presence of acids or PdCl2 to give 1-(1-alkoxyethyl)-2-phenylazopyrroles in up to 49% yield. In the presence of trifluoroacetic acid 2-methylquinoline unexpectedly formed (yield up to 26%) involving into the reaction the phenylazo and 1-vinyl groups.

Fluorescence quenching and laser photolysis of dipyrrolylbenzenes in the presence of chloromethanes

Fluorescence quenching of 1,4-bis(1H-pyrrol-1-yl)benzene, 1-(1H-pyrrol-2-yl)-1-(1-vinyl-1H-pyrrol-1-yl)benzene, and 1,4-bis(1-vinyl-1H-pyrrol-2-yl)benzene with chloromethanes (methylene chloride, chloroform, and carbon tetrachloride) in solvents with different polarities follows electron-transfer mechanism. The occurrence of an electron-transfer step is confirmed by formation of short-lived pyrrolylbenzene radical cations. An exception is quenching of fluorescence of 1,4-bis(1-vinyl-1H-pyrrol-2-yl)benzene in n-hexane in the presence of CCl4 and CHCl3 and in pure CCl4. In this case, neutral 1,4-bis(1-vinyl-1H-pyrrol-2-yl)benzene·-Cl radical is formed via recombination of 1,4-bis(1-vinyl-1H-pyrrol-2-yl)benzene radical cation and chloride anion. A relation was found between the nature of the short-lived species detected by laser photolysis and stable product obtained by stationary photolysis.

13C-13C spin-spin coupling constants in structural studies: XL. Conformational analysis of N-vinylpyrroles

Conformational analysis of ten N-vinylpyrroles was performed on the basis of experimental 13C-1H and 13C-13C coupling constants and those calculated by high-level quantum-chemical methods, and principal relations between JCC and JCH values and stereochemical structure of these compounds were revealed.

Trofimov Reaction with Oximes Derived from Ketosteroids: Steroid-Pyrrole Structures

Steroidal ketone oximes, namely pregnenolone oxime, Δ5-cholesten-3-one oxime, and progesterone dioxime react with acetylene in superbasic systems (Trofimov reaction) to afford steroid-pyrrole assemblies. The process is accompanied by prototropic migration of double bonds in the steroid fragment and vinylation of hydroxy groups in sterols with acetylene. The O-vinyl group can readily be removed by methanolysis.

13C-13C spin-spin coupling constants in structural studies: XXXIX. Nonempirical calculations of heteroaromatic oximes

The results of high-level nonempirical quantum-chemical calculations of 13C-13C coupling constants in twelve heteroaromatic ketone oximes are well consistent with the available experimental data. In all the examined compounds, the effect of the unshared electron pair on the oxime nitrogen atom on JCC strongly predominates over conformational and electronic effects, which makes it possible to unambiguously assign JCC values to different configurations.

IMPROVED METHOD FOR THE SYNTHESIS OF 1-VINYLINDOLE

A highly efficient method has been developed for the synthesis of 1-vinylindole based on the vinylation of indole by acetylene at atmospheric pressure using the superbase KOH–DMSO catalytic system. The method allows the preparation of the 1-vinylindole in 94% yield with a purity of 99% (after a single distillation of the crude product).

Novel BODIPY Preparations from Sterically Hindered Pyrroles. Synthesis and Photophysical Behavior in Solution, Polystyrene Nanoparticles, and Solid Phase

Trimesityl-BODIPY (TMB), a new derivative of 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene belonging to fluores-cent nanostructures series, was synthesized from the corresponding pyrrole by the Trofimov reaction. This reaction was also employed to obtain 2-[2.2]paracyclophanylpyrrole from 5-acetyl[2.2]-paracyclophane. The spectral properties of TMB have been investigated in dichloromethane, nanolatex (polystyrene) films prepared by rapid solvent evaporation, and microcrystals. Comparative analysis of TMB properties with those of mesityl-BODIPY (MB) was performed. TMB was prepared to minimize π-π interactions in order to preserve luminescence in the aggregate state. Both fluorophores were shown to form fluorescing aggregates in the amorphous state (film). Fluorescence spectra (extinction and lifetime) were also studied. In crystal, MB shows a weaker fluorescence, while TMB behaves as a single fluorescing aggregate with a lifetime of 9.5 ns.