Synthesis of indoles from pyridinium salts. 6. Reaction of 3-nitroquinolinium salts with ketones in the presence of amines

It is shown that in the reaction of 3-nitroquinolinium salts with aliphatic ketones and amines the ketone adds to the 2 and 4 positions with the formation of tricyclic adducts — benzazabicyclononane derivatives. Their conformational analysis was carried out on the basis of the NMR spectral data. Intermediate products of the monoaddition of ketones in the 4 position of the heteroring were isolated for the unsubstituted 3-nitroquinolinium salt.See [1] for Communication 5.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1385–1393, October, 1988.     

Synthesis of indoles from pyridinium salts. 4. Ketimines in the synthesis of indoles from 3-nitropyridinium salts

The possibility of using certain ketimines in place of mixtures of ketone and amine in the synthesis of indoles from 3-nitropyridinium salts has been demonstrated. The use of ketimines leads, in many cases, to increased yields of indoles and simplifies their isolation. It has been established that the rate of indole formation is considerably increased in polar aprotic solvents.For Communication 3, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1625–1628, December, 1987.     

Synthesis of indoles from pyridinium salts.

The reaction of 1,2,5,6-tetramethyl-3-nitropyridinium perchlorate with acetone and piperidine on a solid carrier has given the novel, relatively stable 3-nitropyridine anhydro-base, 1,2,5-trimethyl-3-nitro-6-methylene-1,6-dihydropyridine, which bears alkyl groups only. This anhydro-base has been shown not to be an intermediate in the synthesis of indoles from 3-nitropyridinium salts.See [1] for Communication 7.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1214–1216, September, 1990.     

Synthesis of indoles from pyridinium salts

The detailed analysis of the products of the interaction of nitropyridinium salts with ketones and alkylamines resulted in new data testifying in favor of the previously proposed scheme for the formation of indoles from pyridinium salts.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 488–496, April, 1987.     

Synthesis of indoles from pyridinium salts. 7. Sterically hindered alkyl-3-nitropyridinium salts in the synthesis of indoles

The introduction of bulky alkyl substituents (iso-Pr,tert-Bu) into any positions of the starting 3-nitropyridinium salt only increases the reaction time and decreases the yields of the corresponding alkylindoles somewhat.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 805–810, June, 1989.     

Synthesis of indoles from pyridinium salts 5. Secondary amines in the reaction of 3-nitropyridinium salts with acetone

The use of secondary amines in the reaction of 3-nitropyridinium salts with acetone makes it possible to isolate stable intermediates in the formation of indoles — (o-N,N-dialkylaminobenzyl)ketones — and to observe new reaction pathways — the formation of bisindolylpropanes and p-nitroanilines.See [1] for Communication 4.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1213–1221, September, 1988.     

Steric effects in the synthesis of indoles from pyridinium salts

In the synthesis of indoles from pyridinium salts the degree of transamination depends on the character of the alkyl group attached to the nitrogen atom of the amine and its nucleophilicity. The yields of indoles decrease as the steric hindrance becomes greater.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 522–524, April, 1985.     

Synthesis, structural, thermal and optical studies of 1-ethyl-2,6-dimethyl-4-hydroxy pyridinium halides

1-Ethyl-2,6-dimethyl-4-hydroxy pyridinium chloride dihydrate and bromide dihydrate salts have been synthesized and their single crystals were grown by the slow evaporation of aqueous solution at 30 degrees C. The grown crystals were characterized by elemental analysis, FT-NMR and FT-IR techniques to confirm the formation of the expected compound. Optical transmittance window in aqueous solution was found to be 275-1100 nm by UV-vis-NIR technique. Thermogravimetric and differential thermal analyses reveal thermal stability and the presence of two water molecules in the crystal lattices. The crystal structure of chloride salt was also determined by X-ray diffraction method.     

Recyclization reactions. 26. Recyclization of heteroarenium salts by action of acid anhydride in the presence of base

When oxazolium, 1,3,4-thia- and -selenadiazolium, or pyrilium salts react with acid anhydride in the presence of base, they are recyclized to pyrrol, pyrazole, and benzene derivatives, respectively. The typical features of recyclization involving anhydride in a number of five-membered and six-membered systems are discussed.For Communication 25, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1689–1695, December, 1988.     

Synthesis of 1-alkyl-2-arylpyrroles from aryl(3-bromo-2-methoxypropyl)ketones

Aryl(3-bromo-2-methoxypropyl)ketones have been obtained by bromination of allylarylketones using N-bromosuccinimide. When treated with primary amines, good yields of 1-alkyl-2-arylpyrroles were obtained via 1,3-dehydrobromination and subsequent opening of the tricyclic ring in the intermediate aryl(2-methoxycyclopropyl)ketones.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 334–336, March, 1991.     

Recyclization reactions of heterocyles. XVII. Hydrazination of 1, 3, 4-oxadiazolium salts

2, 5-Diaryl-3-alkyl-1, 3, 4-oxadiazolium salts react with hydrazine to give acyclic hydrazinolysis products or products of recyclization with participation of the carbon atom in the 2 position of the oxadiazole ring, i.e., dihydro-sym-tetrazines and N-amino-sym-triazoles (with hydrazine) and 2-phenyl-5-aryl-1, 3, 4-oxadiazoles (with benzoylhydrazine) or formazans (with phenylhydrazine).See [1] for communication XVI.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 629–634, May, 1976.     

Synthesis of 2-alkyl-6-phenyl-3, 4-c cycloheptenopyrylium salts

A method is given for synthesizing 2-alkyl-6-phenyl-3, 4-cycloheptenopyrylium perchlorates, obtained in 45–55% yields by acylating cycloheptenylacetophenone with anhydrides of aliphatic acids in the presence of 70% perchloric acid. Treatment of the pyrylium salts with ammonia gives a good yield of 2-alkyl-6-phenyl -3, 4-cycloheptenopyridine.     

Synthesis and structure of the N-alkyl-2,6-dimethyl-4-oxopyridine-3-carboxylic acids

A range of N-alkyl-2,6-dimethyl-4-oxopyridine-3-carboxylic acids XV have been prepared via reactions of primary alkyl amines with differing 2,6-dimethyl-4-oxopyran-3-carboxylate esters IX . The quantity of desired product formed and the character of by-products formed are determined by the natures of the amine and ester IX respectively. X-ray crystallography data for the N-ethyl analogue of XV indicates very strong intramolecular hydrogen bonding to be present, with the heterocyclic ring exhibiting considerable aromaticity.     

Synthesis of 4-alkyl-3-pyridinols from 3-benzyloxypyridine

The addition of Grignard reagents to the 1-phenoxycarbonyl salt of 3-benzyloxypyridine and a catalytic amount of cuprous iodide afforded 4-alkyl-3-benzyloxy-1-phenoxycarbonyl-1,4-dihydropyridines in good yield. The crude dihydropyridines were aromatized with o-chloranil to give 4-alkyl-3-benzyloxypyridines, which were debenzylated with hydrogen and 10% palladium on carbon to provide 4-alkyl-3-pyridinols.     

Structure absorption spectra correlation in a series of 2,6-dimethyl-4-arylpyrylium salts

A combined experimental and theoretical study of the absorption spectra of a group of closely related pyrylium perchlorates 1-11 are presented. Minor changes in the position of the substituents lead to drastic changes in the absorption spectra in this series of compounds. We have attempted to explain the observed changes using the x,y-band notation developed by Balaban and co-workers. Absorption spectra of all compounds are compared with results from time-dependent density functional theory (TDDFT) and Zerner's intermediate neglect of differential overlap (ZINDO/S) level calculations. Results of the calculations are in good agreement with experimental observations and an interesting correlation between Balaban's notations and the MO transitions are obtained for simple derivatives. It is suggested that for more complex systems such as alpha- and beta-naphthyl substituted systems, the empirical method is not appropriate.     

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.     

An improved preparation of tetrahydropyridines from 1-alkyl-3-acylpyridinium salts

The hydrogenation of 1-alkyl-3-acylpyridinium salts in methanol in the presence of 10% palladium-charcoal/disodium hydrogen phosphate-sodium dihydrogenphosphate suspension leads to the corresponding tetrahydropyridines. This represents an improvement over the Wenkert method.     

Synthesis of 1-alkyl-1,2,4-triazolium 4-nitroimides by alkylation of 4-nitramino-1,2,4-triazole salts

A method for the synthesis of 1-alkyl-1,2,4-triazolium 4-nitroimides was developed based on alkylation of 4-nitramino-1,2,4-triazole Na and Ag salts with halo- and dihaloalkanes.