1,2,3,9a-Tetrahydro-9H-imidazo[1,2-a]indoles

When derivatives of 1,2,3,9a-tetrahydro-9H-imidazo[1,2-a]indol-2-one or 1-carbamoylmethyl-2-methylene-2,3-dihydroindole are reacted with lithium aluminum hydride, derivatives of 1,2,3,9a-tetrahydro-9H-imidazo[1,2-a]indole are formed. Under the same conditions 1-(N-phenylcarbamoylmethyl)-2-methylene-2,3-dihydroindole is not cyclized to an imidazo[1,2-a]indole. WHen treated with proton acids imidazo[1,2-a]indoles are converted to 3H-indolium salts. Opening of the imidazolidine ring is also found when imidazo[1,2-a]indole is acylated with benzoyl chloride.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 227–230, February, 1987.     

Reaction of 2,3,3-trimethyl-3H-indole hydrochloride with methacrylic and crotonic amides

Reaction of 2,3,3-trimethyl-and 2,3,3,5-tetramethyl-3H-indole hydrochlorides with methacrylic and crotonic amides gives 3- and 4-methyl-1,2,3,4,10,10a-hexahydropyrimido[1,2-a]indol-2-ones. With perchloric acid these are converted to 1-carbamoylpropyl-3H-indolium perchlorates. The syntheses of 10a-(4-dimethylaminostyryl)- and 10a-[(4-dimethylaminophenyl)butadienyl]-3,10,10-trimethylpyrimido[1,2-a]indol-2-ones have been studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 625–627, May, 1990.     

New heterocyclic sym-triazolopyrimidinium systems — Quinoline,pyridazine, and phthalazine derivatives

Pyrimido[1′,2′:1,5]-sym-triazolo[4,3-b]pyridazinium, pyrimido[1′,2′:1,5]-sym-triazolo-[4,3-b]phthalazinium, and pyrimido[1′,2′:1,5]-sym-triazolo[4,3-a]quinoliniumsalt derivatives were obtained by condensation of 3-amino-sym-triazolo[4,3-b]pyridazinium, 3-amino-sym-triazolo[3,4-a]phthalazinium, and 1-amino-sym-triazolo[4,3-a]quinolinium salts with β-diketories and 1,1,3,3-tetraethoxypropane. The structures of the reaction products were confirmed by the P MR spectra.     

Study of reaction of 2,3,3-trimethyl-3H-indole with haloacetic acid amides. Synthesis of 1,2,3,9a-tetrahydro-9H-imidazo[1,2-a]indol-2-ones

In the reaction of 2,3,3-trimethyl-3H-indole with -chloro- and -iodoacetamides, 1-carbamoylmethyl-2,3,3-trimethyl-3H-indolium salts are formed, which by the action of bases convert into imidazo[1,2-a]indol-2-one and 1-carbamoyl-2-methylene-2,3-dihydroindole. The latter compound can by cyclized into imidazo[1,2-a]indol-2-one by the action of acetic acid.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 933–935, July, 1985.     

A thermal cascade route to pyrroloisoindolone and pyrroloimidazolones

Flash vacuum pyrolysis (FVP) of indol-1-ylacrylate derivatives 11 and 15 or the isomeric indol-3-ylacrylates 21, 22, and 24 at 925 degrees C (0.05 Torr) provides pyrrolo[1,2-a]indol-3-ones 2, 18, 28, and 29 in 53-90% yield by a cascade mechanism that involves a sigmatropic migration, elimination, electrocyclization sequence. Pyrrolo[1,2-a]imidazol-5-ones 3 and pyrrolo[1,2-c]imidazol-5-ones 4 were similarly obtained by FVP of corresponding 2,5-unsubstituted imidazol-1-ylacrylates (e.g., 33), with the former isomer predominating in ca. 80:20 ratio. Migration to the 2-position is therefore favored in the initial sigmatropic shift. FVP of 2-substituted imidazol-1-ylacrylates 35, 37, and 51 (825-875 degrees C) instead give pyrrolo[1,2-c]imidazol-5-ones 56-58 only (88-91%), and that of 4,5-disubstituted imidazol-1-ylacrylates 39 and 41 (825-850 degrees C) provide pyrrolo[1,2-a]imidazol-5-ones 59 and 60 exclusively (93-95%), and thus the selectivity of the initial shift can be controlled by the presence of substituents on the imidazole 2- and 5-positions. FVP of the benzimidazole analogues 61 and 62 at 950 degrees C gave the pyrrolo[1,2-a]benzimidazol-1-ones 6 (71%) and 63 (36%), respectively.     

Alkylation of 1,2,3,9a-tetrahydro-9H-imidazo[1,2-a]indol-2-ones

Reaction of 1,2,3,9a-tetrahydro-9H-imidazo[1,2-a]indol-2-ones with dimethyl sulfate and haloalkanes in DMF or DMSO in the presence of potassium hydroxide gives the 1-substituted 1,2,3,9a-tetrahydro-9H-imidazo[1,2-a]indol-2-ones (N-substituted products) and 9,9a-dihydro-3H-imidazo[1,2-a]indoles (O-substituted products). The latter, on treatment with acids and bases, are converted into 1-alkoxycarbonylmethyl-2,3-dihydro-1H-indoles. 1-Ethoxycarbonyl-methyl-2,3-dihydro-1H-indoles on treatment with lithium aluminohydride undergoes cyclization to 2,3,9,9a-tetrahydrooxazolo[3,2-a]indole.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 49–53, January, 1988.     

Synthesis of derivatives of the new heterocyclic system pyrimido[4′,5′:4,5]pyrimido[1,2-a]benzimidazole

3-Phenyl-5-methyl(phenyl)-1H,3H-pyrimido[4,5:4,5]pyrimido[1,2-a]benzimi-dazole-2,4-diones were obtained by the cyclization of N-phenyl-N-[3-ethoxycar-bonyl-4-methyl(phenyl)pyrimido [1,2-a]benzimidazol-2-yl]ureas by the action of potassium carbonate. 2-Methyl-5-phenyl-1H-pyrimido[4,5:4,5]pyrimido[1,2-a]benzimidazol-4-one was obtained by the reaction of N-3-ethoxycarbonyl-4-phenylpyrimido[1,2-a]benzimidazol-2-yl]-N,N-dimethylacetamidine with ammonium acetate in ethanol. The synthesized compounds are members of a new heterocyclic system. The molecular and crystal structure of the solvate of 3-phenyl-5-methyl-1H,3H-pyrimido[4,5:4,5] pyrimido[1,2-a]benzimidazole-2,4-dione with two molecules of DMF was studied by x-ray crystallographic analysis.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2587–2592, November, 1991.     

Alkylation of 1,2,3,4,10,10a-hexahydropyrimido[1,2-a]indol-2-one

A mixture of N- and O-alkylation products is formed in the reaction of 1,2,3,4,10,-10a-hexahydropyrimido[1,2-a]indol-2-ones with ethyl iodide, allyl bromide, or benzyl chloride in DMFA (dimethylformamide) in the presence of potassium hydroxide. In the presence of aqueous solutions of acids with subsequent treatment with bases, the alkylation products are converted to 1-[2-(alkoxycarbonyl)-ethyl]-2-methylene-2,3-dehydro-1H-indoles. The reaction of 1,2,3,4,10,10a-hexahydropyrimido[1,2-a]indol-2-one with triethyloxonium fluoroborate gives 1-[2-(ethoxycarbonyl)ethyl]-2-methylene-2,3-dihydro-1H-indole.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1224–1227, September, 1989.     

Synthesis of 1-substituted 1,2,3,9a-tetrahydro-9H-imidazo[1,2-a]indol-2-ones

1-R-9,9,9a-Trimethyl-1,2,3,9a-tetrahydro-9H-imidazo[1,2-a]indol-2-ones and the corresponding 2-methylene-2,3-dihydroindoles were obtained by the reaction of 2,3,3-trimethyl-3H-indole with a number of N-substituted chloroacetic acid amides and subsequent reaction of the resulting quaternary salts with bases. The kinetics of intramolecular cyclization of 1-(N-alkylcarbamoylethyl)-2-methylene-2,3-dihydroindoles under the influence of acetic acid were studied. Under the influence of strong protic acids 1-R-imidazo[1,2-a]indol-2-ones undergo decyclization and are converted to 3H-indolium salts.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1485–1489, November, 1986.     

An Improved Synthesis of 2-Chlorinated Imidazo[1,2-α]-pyridines and the Application of this Procedure for the Synthesis of Several New Polychlorinated Imidazo[1,2-α]Pyridnes.

Polychlorinated imidazo[1,2-α]pyridines were synthesized as analogs of certain chlorinated benzimidazoles. The imidazo[1,2-α]pyridines were obtained by a condensation of ethyl bromoacetate and chlorinated 2-aminopyridines. These condensation products were treated with an ion exchange resin to effect an exchange of hydrobromide salts with hydrochloride salts. These compounds were subsequently treated with POCl₃ to convert the imidazo[1,2-α]pyridin-2-ones into 2-chloroimidazo[1,2-a]pyridines.     

Synthesis of 1,2,3,9a-tetrahydro-9H-imidazo[1,2-<Emphasis Type="Italic">a</Emphasis>]indole-2-thione and 1,5,6,10b-Tetrahydroimidazo[2,1-<Emphasis Type="Italic">a</Emphasis>]-isoquinoline-2(3H)-thione derivatives

Thionation of 1,2,3,9a-tetrahydro-9H-imidazo[1,2-a]indol-2-one derivative with Lawessons reagent in boiling toluene afforded 1,2,3,9a-tetrahydro-9H-imidazo[1,2-a]indole-2-thione derivative. Alkylation of the latter with ethyl iodide in DMF in the presence of a strong base gave 2-ethylthio-9,9,9a-trimethyl-9,9a-dihydro-3H-imidazo[1,2-a]indole. 1,5,6,10b-Tetrahydroimidazo[2,1-a]isoquinoline-2(3H)-thiones were synthesized by thionation of the corresponding carbonyl substrates.Published in Khimiya Geterotsiklicheskikh Soedinenii, No 11, pp. 1695–1700, November, 2004.     

2-Amino-3-(benzimidazol-2-yl)benzo[b]furans

The corresponding 2-amino-3-(benzimidazol-2-yl)benzo[b]furans were obtained by reaction of 2,3,5-trimethyl-1,4-benzoquinone with 2-cyanomethylbenzimidazoles. It is shown that new benzo[b]furo[2′,3′∶4,5]pyrimido[1,6-a]benzimidazole polynuclear heterocyclic systems (bases and quaternary salts) are formed in the reaction of these products with acylating agents. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 164–166, February, 1980.     

Novel synthesis of bicycles with fused pyrrole, indole, oxazole, and imidazole rings

Reactions of benzotriazol-1-yl(1H-pyrrol-2-yl)methanone 10 and benzotriazol-1-yl(1H-indol-2-yl)methanone 11 with diverse ketones, isocyanates, and isothiocyanates in the presence of base afforded pyrrolo[1,2-c]oxazol-1-ones 1, oxazolo[3,4-a]indol-1-ones 2, pyrrolo[1,2-c]imidazoles 3, and imidazo[1,5-a]indoles 4 by a simple one-step procedure.     

Condensation of 1-carbamoylmethyl-2,3,3-trimethyl-3H-indolium chloride with aromatic aldehydes

The reaction of 1-carbamoylmethyl-2,3,3-trimethyl-3H-indolium chloride with various aromatic aldehydes in acetic acid and the subsequent workup of the intermediate styrylic derivatives with strong bases yielded 9a-(2-arylethenyl)-1,2,3,9a-tetrahydro-9H-imidazo[1,2-a]indol-2-one derivatives. Condensation of the mentioned salt with salicylaldehyde in acidic or basic medium afforded the derivative of l-carbamoylmethylspiro[benzopyran-2,2-indole]. Alkylation of the latter compound with benzyl chloride in the presence of potassium hydroxide gave 9a-[2-(2-benzyloxyphenyl)ethenyl]-1,2,3,9a-tetrahydro-9H-imidazo[1,2-a]indol-2-one.Department of Organic Chemistry, Kaunas University of Technology, LT-3028 Kaunas, Lithuania Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 761–769, June, 2000.     

Reactions of 1,2-diaminobenzimidazoles with β-dicarbonyl compounds

The reactions of 1,2-diaminobenzimidazoles with β-dicarbonyl compounds give 1,2,4-triazepino [2,3-a]benzimidazole and pyrimido [1,2-a]benzimidazole-derivatives.     

Reaction of 1-amino-, 2-amino-, and 1,2-diaminoimidazoles with β-diketones

1,2-Diamino-4-phenylimidazolium perchlorate condenses with 2 mole of β-diketones to give pyrimido[2′,1′:2,3]imidazo[1,5-b]pyridazinium derivatives, while, like 1-amino-2-mercapto-4-phenylimidazole, to give imidazo[1,5-b]pyridazine derivatives. Salts of 1-benzylideneamino- and 1-(2-thiazolyl)-2-aminoimidazoles react with β-diketones to give substituted imidazo[1,2-a]pyrimidinium derivatives.     

Triazino-1,2,4-[4,5-a] indoles IV. Etude des triazinoindolethiones

The 1,2-dihy dro-1,2,4-triazino[4,5-a] indole-1-thiones 2 and 3 obtained by sulphurization of the 1,2-dihydro-1,2,4-triazino-[4,5-a] indol-1-ones 1 and 4 with phosphorus pentasulphide are intermediate products in the synthesis of 1,2,4-triazino[4,5-a]-indolc 10 and 4-methyl-1,2,4 omdp;e 19. The thiolactam-thiolactim tautomerism was studied using the ir and nmr spectra and allowed N. and S.substitutions. The methylation with dimethyl sulphate afforded mixtures of N. and S. methyl derivatives which were separated by chromatographic analysis and identified by |21|0H nmr and unequivocal synthesis.     

Reamination in the recyclization of pyrrolo-[1,2-a]pyrazine salts into 6- and 8-aminoindolizines. General process scheme

Rearrangement of the methyl iodides of 1- and 3-alkyl-substituted pyrrolo[1,2-a]pyrazines in the presence of various alkylamines afforded a mixture of 8- and 6-aminoindolizines, respectively, with and without exchange of the methylamine fragment. The ratio of the products of direct and exchange recyclization was dictated by the size of the N-alkyl substituents in the reagent and starting salt. Rearrangement of the 1-alkylpyrrolo[1,2-a]pyrazinium salts proceeded via the breaking of the C₍₃₎ -N₍₂₎ bond, and rearrangement of the 3-alkylpyrrolo-[1,2-a]pyrazinium salts via the breaking of the C₍₁₎ -N₍₂₎ bond.Translated from Khimiya Geterotsiklicheskikikh Soedinenii, No. 11, pp. 1485–1490, November, 1992.     

A simple and efficient one-pot novel synthesis of pyrazolo[3,4-b][1,8]naphthyridine and pyrazolo[3,4-d]pyrimido[1,2-a]pyrimidine derivatives as anti-inflammatory agents

Research on Chemical Intermediates - An efficient one-pot synthesis of novel pyrazolo[3,4-b][1,8]naphthyridine and pyrazolo[3,4-d]pyrimido[1,2-a]pyrimidine derivatives has been investigated from...     

Condensation of 1-Substituted 1,2,3,9a-Tetrahydro-9H-imidazo[1,2-a]indol-2-one Derivatives with Aromatic Aldehydes

Condensation of 1-alkyl-, 1-allyl-, and 1-benzyl-1,2,3,9a-tetrahydro-9H-imidazo[1,2-a]indol-2-ones with benzaldehydes in acetic acid and subsequent treatment of the reaction mixture with potassium hydroxide afforded 1-substituted 9a-(2-phenylethenyl)-1,2,3,9a-tetrahydro-9H-imidazo[1,2-a]indol-2-one derivatives. 1-Methyl- and 1-ethyl-9a-[2-(4-dimethylaminophenyl)ethenyl]-1,2,3,9a-tetrahydro-9H-imidazo[1,2-a]indol-2-ones were synthesized by alkylation of 9a-[2-(4-dimethylaminophenyl)ethenyl]-1,2,3,9a-tetrahydro-9H-imidazo[1,2-a]indol-2-one with methyl- and ethyl iodides in DMF in the presence of a strong base.