Acid-catalyzed acylation of 4-alkyl-3-azapyrylium salts and the synthesis of 4-acylaminopyrylium salts

4-Alkyl-3-azapyrylium salts undergo acylation at the alkyl group under acid-catalyzed conditions to give 4-acylmethyl-3-azapyrylium derivatives, which upon heating in proton-donating solvents recyclize to give 4-acylaminopyrylium salts.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 265–269, February, 1991.     

On the structure of “tetraphenyldipyranyl ether”

The reaction product of 2,6-diphenylpyrylium perchlorate with water in presence of bases, which earlier was assigned the structure of α,α',α″,α″-tetraphenyl-γ,γ'-dipyranyl ether, is identified now as 2,6-dipyranylidene-1, 5-diphenylpentenedione-1,5 from its chemical and spectral properties and by X-ray analysis.Crystals are monoclinic, space group P2₁/n with Z =4 in a unit cell of dimensions a =24.088, b= 9.323, c = 11.289 Å, β = 95.30°. The structure was solved by direct method and refined isotropically to R = 0.126 for 2423 reflections.     

Photomonocyclization of 1,2,6-triarylpyridinium cations

Conclusions It was found by UV spectroscopy and x-ray diffraction analysis that the photocyclization of 1-(3'-halophenyl)-2,4,6-triphenylpyridiniurn cations leads to stable 1,3-diphenyl-11-chloro(bromo)-azoniatriphenylene cations.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 535–540, March, 1982.     

Reactions of heterocyclic cations with nitrogen-containing nucleophiles. 11. Reaction of 2,6-diphenylpyrylium perchlorate with primary amines,hydrazine, and hydroxylamine

The reaction of 2,6-diphenylpyrylium perchlorate with methylamine and various anilines in acetic acid leads to pyridinium salts; 3,4-bispyridinium perchlorates were obtained in dimethylformamide. The reaction of 2,6-diphenylpyrylium perchlorate with hydrazine and the sodium salt of hydroxylamine leads to 3-phenyl-5-phenacyl-2-pyrazoline and -2-isoxazoline.See [1] for Communication 10.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 461–464, April, 1982.     

Synthesis of substituted γ-pyrones

Substituted -pyrones were synthesized by the acylation of phenylacetaldehyde and its enol acetate with acetic and propionic anhydrides in the presence of 70% HClO₄. The mechanism of the reaction is examined, and the IR and PMR spectra of the synthesized -pyrones are presented. Some of their transformations were studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 152–154, February, 1972.     

Condensation of 6-methyl-3-azapyrylium salts to pyrido[1,2-c]pyrimidinium derivatives

Under the influence of DMF/Ac₂O 2,4-diphenyl-6-methyl-3-azapyrylium perchlorates undergo condensation to give pyrido[1,2-c]pyrimidinium perchlorates. The structure of one of the perchlorates was proved by x-ray diffraction analysis.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1556–1561, November, 1991.     

Synthesis of pyrylium salts by condensation of Β-chlorocinnamaldehydes with carbonyl compounds

A method is proposed for the synthesis of unsymmetrical unsubstituted pyrylium salts by condensation of -chlorocinnamaldehydes with methyl and methylene ketones and -dicarbonyl compounds in the presence of HClO₄ or Lewis acids. The probable scheme of the reaction is examined.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1031–1035, August, 1974.     

Spectrophotometric Determination of the Polyiodohalides of Organic Nitrogen-Containing Cations

The following biologically active diiodohalides of organic cations were studied: N-cetylpyridinium, trimethylbenzylammonium, triethylbenzylammonium, and N,N-dimethylmorpholinium diiodochlorides; N-cetylpyridinium, tetramethylammonium, tetrabutylammonium, and N,N-dimethylmorpholinium diiodobromides; and N,N-dimethylmorpholinium and butyroylcholinium triiodides. A simple and rapid procedure was proposed for the determination of the above compounds; it is based on the conversion of organic diiodohalides into the corresponding triiodides (_{300 nm} 4 × 10⁴; _{370 nm} 2 × 10⁴) in the presence of excess potassium iodide (RSD 2%). An extraction–spectrophotometric method was developed for the quantitative determination of the biologically active compounds in pharmaceutical dosage forms based on their ion associates with anionic dyes, erythrosine (m _min = 1.25–3.30 g; RSD 3%) and Bromothymol Blue (m _min = 3.85 g; RSD = 3%), or a cationic dye—1,3-dimethyl-2-(4-morpholinophenyl)azobenzimidazolium phenylsulfate (m _min = 2.32–8.26 g; RSD 4%). The developed procedures were used for monitoring drug substances in model pharmaceutical preparations (RSD 4%).