Protonation and Alkylation of Cross-conjugated Ketones Containing a Terminal N-Methylpyrrole Ring

The protonation and alkylation of cross-conjugated ketones containing a terminal N-methylpyrrole ring takes place at the oxygen atom. Protonation is accompanied by a strong bathochromic shift of the absorption maximum in the electron spectrum, while alkylation leads to ethoxypolymethine salts. The possibility of using these salts for the synthesis of ethoxycyanine dyes was studied.     

Reactions of 2,2-disubstituted 1,1-dicyanoethenes with β-dimethylaminoacrolein aminal and 3-dimethylamino-1,1,3-trimethoxypropane

A reaction of 2,2-disubstituted 1,1-dicyanoethenes with β-dimethylaminoacrolein aminal and 3-dimethylamino-1,1,3-trimethoxypropane leads to substituted 6,6-dicyano-1-dimethyl-aminohexatrienes and an organic salt containing 1,1,9,9-tetracyano-2,8-diphenylnona-2,4,6,8-tetraenide as the anion and (dimethylaminopropenylidene)dimethylammonium as the cation, on the basis of which new cation-anionic polymethine dyes were obtained. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1639–1643, August, 2008.     

Synthesis of estees of δ-aminopentadiene-carboxylic acids

Conclusions We synthesized some esters of-aminopentadienecarboxylic acids, which had an electron-acceptor substituent in the-position, and also some N-alkyl-3-carbamoyl-2-pyridones.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2008–2012, September, 1973.     

Study of the absorption spectra and ionic equilibria of cationic-anionic polymethine dyes

The absorption spectra of a number of cationic-anionic polymethine dyes in polar, low-polarity, and nonpolar solvents were studied. It was established that in polar solvents the absorption spectra represent the sum of the absorption spectra of the cation and anion, whereas in nonpolar and low-polarity solvents, in many cases the appearance of a short-wave absorption band is observed, due to interaction of the chromophores of the cation and anion in ion pairs. In solvents of intermediate polarity (for example, in chloroform and ethyl acetate), a concentration dependence of the absorption spectra is observed, determined by the equilibria of ionic dissociation. The ionic dissociation constants of a number of cationic-anionic dyes in chloroform and ethyl acetate were determined by a conductometric method. The thermodynamic data obtained are compared with the spectral data.N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, 117977 Moscow. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 11, pp. 2524–2532, November, 1992.     

Cis-trans-isomerization of cationic-anionic polymethine dyes

The effect of solvent polarity and ion pair formation oncis-trans-isomerization of cationic-anionic polymethine dyes and of related simple cationic and anionic dyes is studied by flash photolysis. The change in the rate constant for reversecis-trans- isomerization of photoisomers due to the interaction of a cation with an anion in an ion pair is observed in nonpolar solvents. A drop in the yield of the photoisomers to zero is observed for a number of cationic-anionic dyes in weakly polar and nonpolar solvents which is possibly due to steric hindrances in the photoisomerization process in ion pairs.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 719–724, April, 1993.     

Synthesis and valence isomerization of dienicβ-keto esters

Conclusions A number of dienic– keto esters was synthesized and it was shown that a labile equilibrium exists in them between the cis-dienones and -pyrans, and also between the cis- and trans-isomers at the , double bond.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2356–2359, October, 1973.     

Synthesis,spectral properties,and conformations of nonlinear cross-conjugated polyenes containing pyrane or dihydropyridine fragment

New cross-conjugated ω,ω′-dimethylaminopolyenes containing the central pyrane or N-methyldihydropyridine fragment were synthesized. In new compounds, the interaction of the aminopolyene chromophores occurs through the dicyanomethylidene, 1-cyano-1-(4-nitrophenyl)methylidene, or 1,3-dioxoindan-2-ylidene groups in position 4 of the heterocycle. The conformation of the synthesized compounds was determined by 2D ¹H NMR spectroscopy (NOESY and ROESY): the chromophores are arranged at an acute or obtuse angle in the structures with the pyrane or dihydropyridine fragment, respectively. The conformational differences in polyenes result in a drastic change in their spectral properties: for the dyes with an acute angles between the chromophores, the long-wavelength absorption band is less intense, as a rule, than the shorter-wavelength band, while the situation is opposite for the compounds with an obtuse angle. The absorption spectra of the synthesized compounds with dinitrile and other acceptor groups lie in a longer-wavelength region than the absorption spectra of the corresponding compounds with carbonyl acceptor groups. The central bridging substituent NMe decreases the energy of interaction of the chromophores.     

Synthesis of thiacyanine dyes containing coumarin moieties at benzothiazole rings

New bischromophoric dyes (thiacarbocyanine and thiadicarbocyanine) containing coumarin moieties at each of the two benzothiazole systems, as well as monomethinecyanine containing coumarin moiety at only one heterocyclic system, manifest significant batho-chromic shift compared to relative coumarin-free dyes.     

Dienone ⇆ 2H-pyran valence isomerization. (Review)

The researches of the author and her colleagues on the synthesis of -dicarbonyl-containing dienes with various structures and study of their valence isomerization to 2H-pyrans¹H by an¹³C NMR, UV, and IR spectroscopy and flash photolysis are reviewed.N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 14431461, November, 1999.