Hydrogenation of heterocyclic compounds using polymer-containing catalysts

The hydrogenation of a series of oxygen- and nitrogen-containing compounds: furan, sylvan, benzofuran, certain dioxa-compounds, and pyridine, was investigated under mild conditions in the presence of polymer-containing catalysts based on metals of group VIII. The catalysts used were soluble complexes of Pt, Pd, and Rh with various polymers and copolymers. The greatest activity was exhibited by rhodium complexes with carboxyl-containing polymers.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1032–1034, August, 1984.     

Some peculiarities in synthesis of nitrogen-containing heterocyclic compounds on zeolite catalysts

Acid properties of some zeolite catalysts have been studied using IR spectroscopy and compared with data on the selectivity of their catalytic effect in the synthesis of nitrogen-containing compounds from monoethanolamine.

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Liquid phase hydrogenation of some heterocyclic nitrogen compounds over ruthenium catalysts

Results are given for the hydrogenation of some heterocyclic nitrogen compounds (pyrrole, pyridine, indole, quinoline, and acridine) and certain derivatives of them in the liquid phase under pressure, in the presence of ruthenium catalysts. The results obtained indicate that these catalysts are very effective, making it possible to obtain high yields of the corresponding saturated compounds. In the cases of quinoline and acridine, depending on the temperature, double bonds in the polycyclic systems can be selectively hydrogenated.     

Recyclable catalysts for the synthesis of heterocyclic compounds using carbon materials

Heterogeneous catalytic reactions play a major role in the industry to produce a number of compounds that are essential in our daily life. Synthesis of heterocyclic compounds using heterogeneous catalysis is one of the rapidly growing research areas. Inherent ability to produce high selectivity and potentiality to recycle, the catalyst makes the heterogeneous systems more attractive, especially on the industrial scale. Various recyclable catalytic systems have been extensively developed for the synthesis of heterocyclic compounds via dehydration, partial oxidations, three-component couplings, dehydrogenations, and others. Different supports like polymers, metal oxides, and quite recently carbon supports like carbon nanotubes (CNTs), graphene oxide (GO), graphitic nitride (GCN), and nitrogenous carbon materials (NGr) have been widely used to synthesize diverse heterocycles. The use of GO in the synthesis of heterocyclic compounds has been reviewed recently, hence we did not focus on GO in this review. The aim of this review article is to explore the emerging areas of carbon-based heterogeneous materials such as CNTs, GCN, and NGr in the synthesis of heterocycles. This review also focused on the most recent examples, their preparation, and recycling studies of highly excited catalytic systems used for the heterocycles.     

Amino acids in the synthesis of heterocyclic compounds. Transformations of thiazolones into imidazole derivatives

5(4H)-Thiazolone derivative 4 , obtained from N-dithiocarbobenzoxyglycine ( 1 ) and N,N-dimethyl-N′-heteroarylformamidines 3 in acetic anhydride, was rearranged with sodium methoxide in methanol followed by acidification with acetic acid into imidazole-4-carboxylic acid derivatives 5, 6 and 7 . These were further converted with methyl iodide into methylthio derivatives 8 , with hydrogen peroxide into the corresponding disulphide 9 , with hydrazine and amines into hydrazide 10 and amides 11 . In the reactions of 4a and 6a with amines in the presence of dichloromethane symetrically disubstituted methanes 14–18 were formed.     

Transformations of 2,2,6-trimethyl-1,3-dioxen-4-one with heterocyclic amines and other amino compounds

Heterocyclic amines were acetoacetylated with 2,2,6-trimethyl-1,3-dioxen-4-one and the obtained compounds reacted on the reactive methylene group to give C-substituted products. Nitrosation, followed by reduction afforded a pyrazine derivative. Azido- or chloroacetamide were also acetoacetylated, with heterocyclic amines, the corresponding enamines were prepared and reduction of the azido group of 15 afforded compounds 22 and/or amides of substituted 3-oxobutanoic acid 23 . An X-ray structural determination of compound 23a revealed that the orientation about the double bond is Z.     

Polynuclear heterocyclic compounds

When 2, 3(CO)-benzoylene-4-phenyl-5-keto-7, 7-dimethyl-5, 6, 7, 8-tetrahydroquinoline is catalytically hydrogenated using Adams catalyst, the five-membered ring carbonyl group is reduced to an alcohol group. The acetate, urethane, monoxime, and hydrochloride of the reduction product are prepared. Their IR spectra are measured. When 2, 3 (CO)-benzoylene-4-phenyl-5-keto-7, 7-dimethyl-5, 6, 7, 8-tetrahydroquinoline is reduced by zinc dust and glacial acetic acid, both carbonyl groups are reduced to CH₂, and 2, 3 (CH₂)-benzylene-4-phenyl-5-keto-7, 7-dimethyl-5, 6, 7, 8-tetrahydroquinoline is formed.For Part XIX see [2].     

Polyfluorinated heterocyclic compounds

The synthesis of 4,5,6,7-tetrafluorotryptophan; 4,5,6,7-tetrafluoroheteroauxin; and 4,5,6,7-tetrafluorotryptamine from 4,5,6,7-tetrafluoro-3-(N-piperidinomethyl)indole or its quaternary salt with dimethyl sulfate is described.See [1] for communication VI.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 213–214, February, 1971.     

Fluorosulfonyl-containing heterocyclic compounds

Salts of hexafluorodimethylmethionic andα-hydrohexafluoro-2-propane-2-sulfonic acids, the amide of the latter, and a number of sulfones containingα-hydrohexafluoroisopropyl, pentafluoroisopropenyl,Β,Β,Β-trifluoroethyl, and methyl groups were obtained by alkaline hydrolysis, alcoholysis, and ammonolysis of hexafluorodimethyl sulfonene trimer.     

Fluorosulfonyl-containing heterocyclic compounds

Depending on the conditions, -hydrohexafluoroisobutyric anhydride, hexafluorodimethylketene, or hexafluoroisobutenylidene sulfate is formed in the sulfotrioxidation of -hydrohexafluoroisobutyric acid. The sulfotrioxidation of -hydrohexafluoroisobutyric anhydride similarly gives hexafluorodimethylketene or hexafluoroisobutenylidene sulfate.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 13–15, January, 1973.     

Fluorosulfonyl-containing heterocyclic compounds

Hexafluoroisobutenylidene sulfate is a sulfotrioxidizing agent with respect to various olefins; methylenemethionic acid is formed in the case of ethylene, while the corresponding-sulfones are formed in the case of tetrafluoroethylene and vinylidene fluoride. 2,2-Difluoro-2-hydroxy-ethanesulfonic acid sultone is characterized by a capacity for anionotropic transformations; a number of sulfoacetic acid derivatives were obtained on the basis of this sultone.See [1] for communication III.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 178–182, February, 1973.     

Polynuclear heterocyclic compounds

The cyclization of halogenophenyldiindanedionylmethanes to the corresponding halogenophenyldibenzoylenepyrans and dibenzoylenedihydropyridines is investigated. The latter are readily oxidized to dibenzoylenepyridines.For Part XX see [15].     

Polyfluorinated heterocyclic compounds

The treatment of 2-phenyl-4-carbomethoxy-6,7,8,9-tetrafluorobenz[f]oxazepin-1,3 (I), 3-benzamido-5,6,7,8-tetrafluorocoumarin (V), and α-benzamido-β-(2-hydroxy-3,4,5,6-tetrafluorophenyl)-acrylic acid (III) with a mixture of glacial acetic acid and a mineral acid gave (IV), the π-complex of 3-hydroxy-5,6,7,8-tetrafluorocoumarin (VII) and benzoic acid. Treatment of (IV) with acetic anhydride gave 3-acetoxy-5,6,7,8-tetrafluorocoumarin (VI) and benzoic acid. Treatment with diazomethane gave 3-methoxy-5,6,7,8-tetrafluorocoumarin (VIII) and methyl benzoate. IV was also obtained from an equimolar mixture of its components. A mechanism for the formation of IV from I is proposed.     

Polyfluorinated heterocyclic compounds

The formylation, aminomethylation, and bromination of 4,5,6,7-tetrafluoroindole were investigated. It is shown that these reactions proceed at the 3 position and that the direction of substitution is in agreement with calculations from the Hiickel molecular orbital method.For Communication V, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1344–1347, October, 1970.     

Polyfluorinated heterocyclic compounds

The treatment of 2-phenyl-4-carbomethoxy-6,7,8,9-tetrafluorobenz[f]oxazepin-1,3 (I), 3-benzamido-5,6,7,8-tetrafluorocoumarin (V), and -benzamido--(2-hydroxy-3,4,5,6-tetrafluorophenyl)-acrylic acid (III) with a mixture of glacial acetic acid and a mineral acid gave (IV), the -complex of 3-hydroxy-5,6,7,8-tetrafluorocoumarin (VII) and benzoic acid. Treatment of (IV) with acetic anhydride gave 3-acetoxy-5,6,7,8-tetrafluorocoumarin (VI) and benzoic acid. Treatment with diazomethane gave 3-methoxy-5,6,7,8-tetrafluorocoumarin (VIII) and methyl benzoate. IV was also obtained from an equimolar mixture of its components. A mechanism for the formation of IV from I is proposed.For part II, see [1].     

Fluorosulfonyl-containing heterocyclic compounds

When hexafluoroisobutenylidene sulfate is heated above 80°C, hexafluorodimethylketene is liberated and the inner anhydride of hexafluoro--pyrosulfoisobutyric acid (I) is formed. On storage, anhydride I is spontaneously isomerized to hexafluoroisobutenylidene pyrosulfate, which is converted to the mixed anhydride of pentafluoromethacrylic and fluoropyrosulfonic acids on heating above 130° for many hours. On heating above 160°, I is decarboxylated to give hexafluoropropane-2,2-disulfonic acid anhydride, which is inclined to isomerize to pentafluoropropene-2-pyrosulfonyl fluoride.See [1] for Communication IV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No, 10, pp. 1321–1324, October, 1973.     

Polynuclear heterocyclic compounds

Spectroscopic constants of dibenzoylenepyrans, dibenzoylene-1,4-dihydropyridine, and dibenzoylenepyridines are given. It is shown that the UV spectrum bands of dibenzoylenepyrans are slightly displaced when substituents are changed. Both in character and in band position the absorption curves for dibenzoylene-1,4-dihydropyridines differ from those of the simpler 1,4-dihydropyridines, and the maxima are displaced in a way depending on the substituents. On the other hand, the spectra of anyldibenzoylenepyridines are almost identical, and coincide with the spectrum of dibenzoylenepyridine.For Part XXI see [6].