Imidazo[1,2-a]quinoxaline and its transformations. I

The transformations that occur during the reduction of 1-(o-nitrophenyl)-2-formylimidazole with sodium hydrosulfite in the presence of ammonia were studied. The 4-amino derivatives of imidazo[1,2-a]quinoxaline and the bisulfite derivatives of 1-(o-aminophenyl)-2-formylimidazole are formed along with the previously described imidazo[1,2-a]quinoxaline. 4-Aminoimidazo[1,2-a]quinoxaline was also obtained by alternative synthesis by amination of imidazo-[1,2-a]quinoxaline with sodium amide in dimethylaniline. The major product of the transformation is 4,4-bisimidazo[1,2-a]quinoxalyl when the reaction is carried out in xylene.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 416–418, March, 1972.     

A new method for the synthesis of pyrrolo[1,2-a]pyrazines and pyrrolo[1,2-a] quinoxalines

A new method is proposed for the synthesis of pyrrolo[1,2-a]pyrazines and pyrrolo[1,2-a]-quinoxalines. By the alkylation of sodium derivatives of 2-acylpyrroles with -bromo carbonyl compounds or their acetals and subsequent treatment of the reaction products with ammonium acetate in acetic acid, a number of derivatives of pyrrolo[1,2-a]pyrazine, including the first member of the class, pyrrolo[1,2-a]pyrazine itself, have been obtained. Similarly, from 2-benzoylpyrrole and the dimethyl ketal of -bromocyclohexanone was obtained 4-phenyltetrahydropyrrolo[1,2-a]quinoxaline, which readily dehydrogenates in the presence of Raney nickel to form 4-phenylpyrrolo[1,2-a]quinoxaline.Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 6, No. 8, pp.1048–1050, August, 1970.     

Cyclocondensation of 5-benzoyl-3-ethoxycarbonyl-6-methylthio-1-R-1,2-dihydropyrid-2-ones with heterocyclic N,N-and N,C-1,3-dinucleophiles

[3+3] Cyclocondensation of 5-benzoyl-3-ethoxycarbonyl-6-methylthio-1-R-1,2-dihydropyrid-2-ones with heterocyclic N,N-and N,C-1,3-dinucleophiles proceeds regioselectively to give a series of new tri-and tetracyclic heterosystems, viz. derivatives of 5,6-dihydropyrazolo[1,5-a]pyrido[2,3-d]pyrimidin-6-one, 1,2-dihydropyrido[2,3-d]pyrido[2′,3′: 3,4]pyrazolo[1,5-a]pyrimidin-2-one, 8,9-dihydro-5H-pyrido-[2,3-d]thiazolo[3,2-a]pyrimidin-8-one, 1,2-dihydrobenzo[4,5]imidazo[1,2-a]pyrido[2,3-d]pyrimidin-2-one, and 1,2-dihydrobenzo[4,5]imidazo[1,2-g][1,6]naphthyridin-2-one.     

Investigations in the imidazole series

2,3-Dihydro derivatives of naphth[1,2-d]imidazo[3,2-b]imidazole were synthesized by the reaction of 2-chloro-3-(-haloalkyl)naphth[1,2-d]imidazole with ammonia and primary amines and by the reaction of 2-chloro-3-(-hydroxyaIkyl)naphth[1,2-d]imidazole with ammonia and amines with subsequent cyclization of the resulting 2-amino(alkylamino, arylamino)-3-(-hydroxyalkyl)naphth[1,2-d]imidazoles under the influence of thionyl chloride or phosphorus oxychloride. Dihydro derivatives of the condensed naphth[1,2-d]imidazo[3,2-b]imidazole system have not been described in the literature.See [1] for communication LX.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1125–1127, August, 1971.     

New simple laboratory method for the synthesis of pirazidol

5,6-Dihydro-8-methyl-4H-pyrazino[3,2,1-j,k]carbazole was obtained by the reaction of -bromoacetaldehyde dibutylacetal, ammonium acetate, and 1,2,3,4-tetrahydro-6-methyl-1-ketocarbazole in acetic acid. The reduction of 5,6-dihydro-8-methyl-4H-pyrazino[3,2,1-j,k]carbazole or its hydrochloride with sodium borohydride leads to 2,3,3a,4,5,6-hexahydro-8-methyl-1H-pyrazino[3,2,1-j,k]carbazole hydrochloride — the medicinal preparation pirazidol.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1362–1363, October, 1983.     

New Synthesis of Diazepino[3,2,1‐ij]quinoline and Pyrido[1,2,3‐de]quinoxalines via Addition–Elimination Followed by Cycloacylation

This paper describes a convenient and efficient synthesis of new fused tricyclic diazepino[3,2,1‐ij]quinolines and substituted pyrido[1,2,3‐de]quinoxalines. o‐Phenylenediamines are transformed in the tricycle nucleus in only a few‐step synthetic sequence to produce ethyl 2,8‐dioxo‐1,2,3,4‐tetrahydro‐8H [1,4]diazepino[3,2,1‐ij]quinoline‐7‐carboxylate, ethyl 8‐oxo‐1,2,3,4‐tetrahydro‐8H‐[1,4]diazepino[3,2,1‐ij]quinoline‐7‐carboxylate and ethyl 2,7‐dioxo‐2,3‐dihydro‐1H,7H‐pyrido[1,2,3‐de]quinoxaline‐6‐carboxylate. The method is economical and simple to perform.     

Studies of imidazo[1,2-a]benzimidazole derivatives. 21. Synthesis of haloketones in the imidazo[1,2-a] benzimidazole series

Methods for the synthesis of imidazo[1,2-a]benzimidazole haloketone derivatives have been investigated. It has been found that -bromoketone derivatives of this heterocycle can be prepared either by bromination of 3-acylimidazo[1,2-a]benz-imidazoles with bromine in glacial acetic acid or by acylation of 3-unsubstituted imidazo[1,2-a]benzimidazoles with haloanhydride derivatives of -bromoalkanoic acids. Treatment of imidazo[1,2-a]benzimidazoles with 3-chloropropionyl chloride results in the formation of imidazo[1,2-a]benzimidazolyl-3-propionyl chloride and bis(imidazo[1,2-a]benzimidazolyl)propan-3-one derivatives as side products. Reaction of 2-phenylimidazo[1,2-a]benzimidazoles with 3-bromopropionic acid in polyphosphoric acid gives benzocyclohepten[5,6:4,5]imidazo[1,2-a]benzimidazole derivatives.For Communication 20, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 339–345, March, 1986.     

Investigations in the imidazole series

The reactions of 2-mercaptonaphth[1,2-d]imidazole with 1,2-dichloro- and 1,2-dibromoethanes and the cyclization of 3-(-hydroxyethyl)- and 2-(-hydroxyethyl)mercaptonaphth[1,2-d]imidazoles were studied. 2,3-Dihydro derivatives of naphth[1,2-d]imidazo[1,2-b]thiazole and naphth[1,2-d]imidazo[3,2-b]thiazole were obtained.See [1] for communication LXX.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 257–259, February, 1972.     

Investigation of the products of the reaction of epichlorohydrin with aromatic amines

The action of hydrogen halides on 7a,8-dihydro-7H-azirino[1,2-]benz[g]indole gives 2-halomethyl-2,3-dihydro-1H-benz[g]indoles and 3-halo-1,2,3,4-tetrahydrobenzo[h]quinolines, which were converted to the corresponding N-nitroso derivatives and then to the isonitroso derivatives. 2-(Benzoxymethyl)-2,3-dihydro-1H-benz[g]indole hydrohalides were obtained by heating 1-benzoyl-2-halomethyl-2,3-dihydro-1H-benz[g]indoles. The reaction of 3-halo-1,2,3,4-tetrahydrobenzo[h]quinolines with thionyl chloride at room temperature gives 3-halo-6-chloro-1,2,3,4-tetrahydrobenzo[h]quinolines, while refluxing with thionyl chloride gives 6-chlorobenzo[h]quinoline.See [1] for communication XVI.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 342–346, March, 1973.     

Novel routes to 1,2,3,4-tetrahydropyrrolo[1,2-a]pyrazines and 5,6,9,10,11,11a-hexahydro-8H-pyrido[1,2-a]pyrrolo[2,1-c]pyrazines

Condensation reactions of benzotriazole and 2-(pyrrol-1-yl)-1-ethylamine (1) with formaldehyde and glutaric dialdehyde, respectively, afforded intermediates 2 and 6. Subsequent nucleophilic substitutions of the benzotriazole group in 2 and 6 with Grignard reagents, sodium cyanide, and sodium borohydride gave 1,2,3,4-tetrahydropyrrolo[1,2-a]pyrazines 3a-e, 4, 5 and 5,6,9,10,11,11a-hexahydro-8H-pyrido[1,2-a]pyrrolo[2,1-c]pyrazines 7a-c, 8, 9, respectively, in good yields.     

Quinolizines and indolizines. Part 16 . Synthesis of pyrrolo[3,2,1-ij]quinolin-4-ones with potential fungicidal activity

The synthesis of some derivatives of 1,2,5,6-tetrahydro-4H-pyrrolo[3,2,1-ij]quinolin-4-one (pyroquilon) having potential fungicidal activity has been accomplished starting with readily available 6-hydroxy-1,2-dihydro-4-pyrrolo[3,2,1-ij]quinolin-4-ones 3, 7. Functionalization in 6- or 5-position gave rise to the corresponding 6-and 5-substituted derivatives 8-12, 17 and 13-16, 20, 21 respectively. The formation of pyrrolo[3,2,1-ij]-pyrano[3,2-c]quinolines ( 5, 22, 23 ) and their degradation to acyl-substituted derivatives of 7 was studied.     

Synthesis of pyrrolo[1,2-a]quinoxaline derivatives by the reaction of 2-hydroxy-1,5-diketones with o-phenylenediamine

The reaction of 2-hydroxy-1,5-diketones with o-phenylenediamine leads to the formation of 4,5-dihydropyrrolo[1,2-a]quinoxaline derivatives, which are dehydrogenated by the action of MnO₂ to give the corresponding pyrrolo[1,2-a]quinoxaline derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 112–115, January, 1992.     

Investigation of the products of the reaction of epichlorohydrin with aromatic amines

The synthesis of 2-(hydroxymethyl)benz [g]indoline derivatives by heating N-acyl derivatives of 2-(chloromethyl)benz[g]indoline in dimethyl sulfoxide is described. 3,6-Dichloro-1,2,3,4-tetrahydrobenzo[h]quinoline, 5-chloroazirido[1,2-a]benz[g]indoline, and derivatives of 2-substituted 5-chlorobenz [g]indoline were synthesized.See [1] for communication XITranslated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1111–1116, August, 1972.     

Chloral as a formylating agent for some bridge heterosystems

The interaction of condensed nitrogen-containing bridge systems with chloral has been studied and the high sensitivity of the reaction to the -excess of the initial heteroaromatic system has been established. It has been shown that chloral is a convenient formylating agent for systems with a moderate -excess —imidazo[l,2-a]imidazole, 9H-imidazo[1,2-a]benzimidazole, imidazo[1,2-a]pyridine, imidazo[1,2-a]naphtho[2,3-d]imidazole. Heterocycles with a high -excess (indolizine, pyrrolo[1,2-a]benzimidazole) form cyanine dyes under the action of chloral. Systems with a lowered -excess (1H-imidazo[1,2-a]benzimidazole, imidazo[1,2-a]quinoline, imidazo[2,1-a]isoquinoline, imidazo[1,2-a]perimidine, imidazo[5,1-b]benzoxazole, imidazo[1,2-a]benzothiazole, and imidazo[1,2-a]pyrimidine) do not react with chloral in a neutral medium. However, in a number of cases their foraylation can be carried out in an acid medium.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 528–537, April, 1980.     

Tetracyclic phenothiazines V. Construction of the azepino[3,2,1-kl] -phenothiazine ring system by regioselective ring expansion

Solvolysis of 1,2-dihydro-3-hydroxy-3-(p-toluenesolfonyloxymethyl) 3H-pyrido[3,2,1-kl]-phenothiazine gave 1,2,3,4-tetrahydroazepino[3,2,1-kl]phenothiazin-3-one.     

Investigations in the imidazole series LXXII. Synthesis of naphth[1,2-d]imidazo[3,2-b]-3-thiazolidone and its derivatives

Naphth[1,2-d]imidazo[3,2-b]-3-thiazolidone and its methyl homolog were synthesized by the reaction of 2-mercaptonaphth[1,2-d]imidazole with chloroacetic and -chloropropionic acids with subsequent cyclization of the naphth[1,2-d]imidazole-2-mercaptoacetic acids. The reactions of the first of them at the methylene group with aldehydes, nitroso compounds, and benzenediazonium salts were studied; the corresponding arylidene and azomethine derivatives of naphthimidazo-3-thiazolidone and the arylhydrazones of naphth[1,2-d]imidazo[3,2-b]thiazoline-2,3-dione were obtained. The arylidene derivatives of naphthimidazo-3-thiazolidone were also obtained by the reaction of naphthimidazole-2-mercaptoacetic acid or its methyl ester with aldehydes or (in one step) by the reaction of 2-mercaptonaphth[1,2-d]imidazole with chloroacetic acid and carbonyl compounds.See [1] for communication LXXI.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 399–402, March, 1972.     

Transformations of 5-methyl-6-carbethoxy-3,4-dihydrothieno-[2,3-d]pyrimidine for synthesis of 4-methoxy-, 4-alkylamino-, and other derivatives of thieno[2,3-d]pyrimidine

4-Chloro derivatives of thieno[2,3-d]pyrimidine are formed by the action of phosphorus oxychloride on 5-methyl- and 5-methyl-6-carbethoxythieno[2,3-d]pyrimidin-4-ones. Action of nucleophilic reagents (methanol, sodium methylate, primary and secondary amines) on these chloro derivatives gave 4-methoxy-, 4-alkylamino-, and 4-dialkylamino substituted thieno[2,3-d]pyrimidines. It was found that 4-methoxy derivatives of thieno[2,3-d]pyrimidines undergo a thermal rearrangement into 3-methyl-substituted thieno[2,3-d]pyrimid-4-ones. In the bromination of 5-methyl-4-chloro- and 5-methyl-4-methoxy-substituted thieno[2,3-d]pyrimidines by N-bromosuccinimide, 5-bromomethyl derivatives of thieno[2,3-d]pyrimidine are formed, from which, by the action of primary and secondary amines, 5-aminomethyl-substituted thieno[2,3-d]pyrimidines were obtained. A synthesis of 1,2,3,4-tetrahydro-1,3-diazepino[4a,10-d,e] thieno[2,3-d]pyrimidines was also carried out.Deceased.Translated from Khimiya Geterotsilicheskikh Soedinenii, No. 7, pp. 925–928, July, 1985.     

Synthesis, spectra, and theoretical investigations of the triarylamines based on 6H-indolo[2,3-b]quinoxaline

Triarylamines containing a 6H-indolo[2,3-b]quinoxaline core and aromatic units such as phenyl, naphthyl, pyrene, anthracene, or fluorene have been synthesized by employing palladium-catalyzed C-N and C-C coupling reactions and characterized by optical absorption and emission spectra, electrochemical behavior, and thermal studies. Even though the electronic absorption spectra of the compounds were influenced by the nature of the peripheral amines, the emission spectra indicated close similarity for the excited states in these compounds. For the derivatives in which the amines were directly anchored on the 6H-indolo[2,3-b]quinoxaline nucleus, the emission appeared to be dominated by the state localized on the 6H-indolo[2,3-b]quinoxaline chromophore, while in the compounds containing the extended conjugation the fluorescence originated from the polyaromatic linker. The compounds displayed green or yellow emission depending on the nature of the amine segment. All of the dyes displayed one-electron quasi-reversible oxidation couple in the cyclic voltammograms, which is attributable to the oxidation of the peripheral amines at the 6H-indolo[2,3-b]quinoxaline core. An additional one-electron oxidation process observable at the high positive potentials for the compounds 7 and 8 probably arises from the oxidation of the arylthiophene segment. The enhanced thermal stability and relatively higher glass transition temperatures observed for these compounds were attributed to the presence of dipolar 6H-indolo[2,3-b]quinoxaline segment. The origin of the optical spectra and the trends observed therein were rationalized using TDDFT simulations.     

Convenient Way to the Synthesis of Polycyclic Fused Benzimidazole Derivatives with a Bridgehead Nitrogen Atom

Effective synthesis was developed for 1,2,3,4-tetrahydropyrido- and pyrido[1,2-a]benzimidazole-7,8-diamines that underlie the preparation of new polyazaheterocycles: pyrido[1,2-а]imidazo[4,5-f]-benzimidazole, 7Н-pyrido[1,2-а]imidazo[4,5-f]benzotriazole, pyrido[1,2-а]imidazo[4,5-g]quinoxaline.     

Synthesis of 9,10-dihydro-8bH-quino[1,2-f]phenanthridine- and 6-phenyl-4,5,6,7-tetrahydropyrido[3,2,1-j,k]-carbazole-derivatives

9,10 - dihydro - 8bH - quino[1,2-f]phenanthridine - derivatives 2 and 6 - phenyl - 4,5,6,7 -tetrahydropyrido[3,2,1 -j,k]carbazole - derivatives 17 were synthesized by photodehydrogenation of the 1,2 -diphenylquinoliniumperchlorates 7 and the 1,2 - diphenyl -1,2,3,4 - tetrahydroquinolines 1 respectively.The intermediate 1,2 - diphenylquinoliniumsalts 7 were obtained by Skraup-synthesis between diphenylamine and acrolein, followed by a Grignard-reaction and iodine/sodiumacetate oxidation. The intermediate tetrahydroquinoline derivatives 1 were prepared by t catalyzed cyclization of the corresponding 3 - (o - anilinophenyl) - 1 - phenyl - 1 - propanol - derivatives 16 and platinum(IV)oxide/palladium on activated carbon-reduction of the higher mentioned 1,2 - diphenylquinoliniumsalts 7.