Recyclization of 1,3-dimethylbenzo[b]furo[2,3-c]- and 1,3-dimethylbenzo[b]thieno[2,3-c]pyrylium when treated with secondary amines. Synthesis of 3-dialkylamino derivatives of dibenzofuran and dibenzothiophene

We have established that 2,4-dimethylbenzo[b]furo[3,2-c]pyrylium and 2,4-dimethylbenzo[b]thieno[3,2-c]pyrylium salts can undergo recyclization to 3-dialkylamino derivatives of dibenzofuran and dibenzothiophene when treated with secondary amines. We compare the physicochemical and spectral characteristics of the compounds obtained with the recyclization products of 1,3-dimethylbenzo[b]furo[2,3-c]- and 1,3-dimethylbenzo[b]thieno[2,3-c]pyrylium salts. L. M. Litvinenko Institute of Physical Organic Chemistry and Coal Chemistry, National Academy of Sciences of Ukraine, Donetsk 340114. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 182–185, February, 1998.     

Synthesis of condensed heterocyclic systems based on thioindoxyl

Substituted benzo[b]thieno[3,2-b]pyrylium salts and dibenzo[b,g]thieno[3,2-b; 2, 3-e]pyrylium salts, which are converted to the corresponding pyridines on refluxing with ammonium acetate in glacial acetic acid, were synthesized by acid condensation of 3-thioindoxyl with aldehydehydes of the aromatic and heteroaromatic series in the presence of perchloric acid.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1181–1185, September, 1976.     

A versatile synthesis of benzothieno-annelated 1,2-dihydropyridine and 1,2,3,4-tetrahydropyridine derivatives: the effect of the structure of benzothieno-annelated pyridinium salts on their reduction by sodium borohydride

Abstract  

Benzothieno[2,3-c]pyridinium and benzothieno[2,3-c]quinolinium salts were synthesized either by quaternization of benzothieno[2,3-c]pyridines, or recyclization of benzothieno[2,3-c]pyrylium salts with primary amines. One-pot synthesis of benzothieno[3,2-g]indolizinium salts from 1-(3-chloropropyl)-benzothieno[2,3-c]pyrylium included consequent recyclization of the pyrylium core by ammonia into a pyridine intermediate and its further intramolecular quaternization reaction. Depending on the structure of benzothieno-annelated pyridinium salts, their reaction with sodium borohydride in methanol results in reduction of the pyridine core into tetrahydropyridine or dihydropyridine derivatives. Whereas reduction of benzothieno[2,3-c]pyridinium and benzothieno[3,2-g]indolizinium salts readily yields benzothieno-annelated tetrahydropyridines as a complex mixture of stereoisomers, reduction of benzothieno[2,3-c]quinolinium salts results in dihydropyridine derivatives. The structure of the latter, in particular, was confirmed by single-crystal X-ray diffraction analysis.     

IR spectra of selenophenopyrylium salts

On the basis of the IR spectra of 16 alkyl-substituted selenopheno[2,3-c]- and selenopheno-[3,2-c]pyrylium salts and a model calculation of the frequencies and the forms of their normal vibrations, an assignment of the frequencies of the skeletal vibrations of the heterocycles is put forward.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1495–1497, November, 1973.     

Selenopheno [3,2-c]pyrylium salts synthesis and some reactions

A method has been developed for the synthesis of selenopheno[3,2-c]pyrylium salts by the acylation of 2-acetonyl derivatives of selenophene homologs, and their reactions with nucleophilic reagents have been investigated.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1212–1215, September, 1973.     

Oxonium Salts in the Synthesis and Spectral Behavior of Pyrano(pyrylium)‐mono methine Cyanine Dyes

Pyrano‐ and pyrylium mono‐8[4(1)] and/or 5(6)‐[2(4)]methine cyanine dyes ( 6a–k , 7a–f ) were synthesized based on acyclic heterocyclic Schiff bases of pyrolo[3,2‐d]pyrazole[oxazole(imidazol‐6‐one)]‐1‐ium iodide salts, 5‐acetyl‐N‐aryl[pyrazolinyl(pyridinyl)]pyrolo‐[5,4‐d]pyrazolin‐iodide salts, and/or (anhydro bases) precursors ( 1a–i , 2a–I , 3a–i , 4a–i , and 5A,Ba–i ). The structure of pyrylium‐9‐chloride and/or iodide and their pyrano(pyrylium)‐mono‐8[4(1)] and 5(6)[2(4)]methine cyanine dyes was identified by elemental and spectral data. The absorption spectra of some selected dyes were investigated in 95% EtOH, polar (nonpolar) organic solvents and in universal buffer solutions to investigate the optimal conditions for the application of such dyes as photosensitizers.     

Interaction of benzothieno[2,3-c]pyrylium salts with hydrazine. Derivatives of 5H-[2,3]benzothieno[2,3-e]diazepines

A study has been made of the reaction of 1,3-disubstituted bezothieno[2,3-c]pyrylium salts with hydrazine. It has been shown that 1,3-dialkyl-substituted benzothieno[2,3-c]pyrylium salts interact with hydrazine to give N-amino-1,3-dialkylbenzothieno[2,3-c]pyridines. The presence of a pyrylium ring on one of the positions of the phenyl group leads to a mixture of N-amino derivatives and 5H-[2,3]benzothieno[2,3-e]diazepines. In contrast, 1,3-diphenylbenzothieno[2,3-c]pyrylium perchlorate gives exclusively 5H-[2,3]benzothieno[2,3-e]diazepine.L. M. Litvinenko Institute of Physical Organic Chemistry and Coal Tar Chemistry, National Academy of Sciences of Ukraine, Donetsk 340114. Translate from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp 1137–1140, August, 1998.     

Investigations in the field of lipids

Summary A number of derivatives of androstano [3, 2-b] pyrylium and androst-13-eno-[3, 2-b] pyrylium derivatives forming a new class of heterocyclic steroids has been obtained.Khimiya Prirodnykh Soedinenii, Vol. 1, No. 5, pp. 318–321, 1965     

Pyrylium derivatives of steroid hydroxymethyleneketones

Chemistry of Natural Compounds - A number of derivatives of androstano [3, 2-b] pyrylium and androst-13-eno-[3, 2-b] pyrylium derivatives forming a new class of heterocyclic steroids has been...     

Synthesis and reactions of benzo[b]furo[2,3-c]pyrylium salts

A method has been developed for the synthesis of 3-acetonyl- and 3-phenacylben-zo[b]furans by cyclization of 1-arloxy-2,4-pentanediones and 1-phenyl-4-aryloxy-1,3-butanediones in polyphosphoric acid. Acylation of 3-acetonyl(phenyl-benzo-[b]furans with aliphatic acid anhydrides in the presence of perchloric acid gives the benzo[b]furo[2,3-c]pyrylium perchlorates. The recyclization of the pyrylium salts with ammonia, aqueous alkali, and morpholine has been examined.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 889–893, July, 1987.     

Reactions of functionally substituted benzo[c]pyrylium salts. Synthesis of 5h-benzo-2,3-diazepines

5H-Benzo-2,3-diazepine derivatives are formed in the reaction of 4-ethoxycarbonylbenzo[c]pyrylium perchlorates with excess hydrazine hydrate. It was established that the key intermediate in the reaction is the 2-aminoisoquinolinium cation. A method for the recyclization of 4-cyanobenzo[c]pyrylium salts to 5H-benzo-2,3-diazepine derivatives was found.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1475–1477, November, 1993.     

Condensed pyridine bases. A new approach to the synthesis of 3-phenacylbenzo[b]thiophenes and 3-phenacyl-5-ethylthieno[2,3-b]thiophene. Synthesis of new derivatives of benzothieno[2,3-c]pyrylium and thieno[2′,3′:5,4]thieno-[2,3-c]pyrylium and pyridine bases

A new method is proposed for the production of substituted 3-phenacylbenzo[b]thiophenes by the intramolecular cyclization of 1-phenyl-4-phenylthio-1,3-butanediones in polyphosphoric acid. The analogous cyclization of 1-phenyl-4-(5-ethyl-2-thienylthio)-1,3-butanedione leads to 3-phenacyl-5-ethylthieno[2,3-b]thiophene. The acylation of substituted 3-phenacylbenzo[b]thiophenes and 3-phenacyl-5-ethylthieno[2,3-b]thiophene by the anhydrides of aliphatic acids in the presence of perchloric acid leads to 1-alkyl-3-phenylbenzothieno[2,3-c]pyrylium perchlorates and 2-ethyl-5-phenyl-7-methylthieno[2′,3′:5,4]thieno[2,3-c]pyrylium perchlorate. The action of ammonium acetate on the obtained salts gives the corresponding pyridine bases. L. M. Litvinenko Institute of Physical Organic Chemistry and Coal Chemistry, National Academy of Sciences of Ukraine, Donetsk 340114. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1335–1339, October, 1998.     

Synthesis of thieno [3,4-c ]- and selenopheno[3,4-c] pyrylium salts

Acylation of 3-acetonyl- and 3-phenacyl-2,5-dimethylthiophenes with aliphatic acid anhydrides in the presence of perchloric acid gives thieno[3,4-c]pyrylium perchlorates. Reaction of the latter with ammonia gives the corresponding thieno[3,4-c]pyridines or diketones of the thiophene series. Selenopheno[3,4-c]pyrylium salts could not be isolated in the acylation of 3-acetonyl- and 3-phenacyl-2,5-dimethylselenophenes.     

Ring transformations of heterocyclic compounds. XVI. Spiro[cyclohexadiene-dihydroacridines]. A novel class of spirodihydroacridines by ring transformation of pyrylium salts with 9-methylacridine and its quaternary salts

2,4,6-Triarylpyrylium salts 1 react with the in situ generated anhydrobase of 9,10-dimethylacridinium methosulfate ( 2a ) in the presence of anhydrous sodium acetate in ethanol by a 2,5-[C₄+C₂] pyrylium ring transformation to give the hitherto unknown 6-aroyl-3,5-diaryl-10′-methylspiro[cyclohexa-2,4-diene-1,9′-9′,10′-dihydro-acridines] 3 . When the pyrylium perchlorate 1a is treated under the same conditions with the N-ethyl, N-allyl or N-benzyl substituted acridinium salts 2b-d a dealkylation of these salts occurs and the N-unsubstituted spiro[cyclohexadiene-dihydroacridine] 4a is formed. The same compounds 4 can also be obtained by transformation of the pyrylium salts 1 with 9-methylacridine ( 7 ) and triefhylamine/acetic acid in ethanol. Structure elucidation is performed by an X-ray crystal structure determination of the spiro[cyclohexadiene-dihydroacridine] 3a . Spectroscopic data of the transformation products and their mode of formation are discussed.     

Condensed isoquinolines 26. Oxidation reactions of 6,11-dihydro-13H-isoquino-[3,2-<Emphasis Type="Italic">b</Emphasis>]quinazolin-13-one derivatives

Oxidation of the hydrobromide of 6,11-dihydro-13H-isoquino[3,2-b]quinazolin-13-one with dimethyl sulfoxide leads to 11-hydroxy-11H-isoquino[3,2-b]quinazoline-6,13-dione, and with hydrogen peroxide to the hydrobromide of 2-[(4-oxo-3,4-dihydro-2-quinazolinyl)carbonyl]benzoic acid. Salts of 5-and 6-alkyl-substituted isoquino[3,2-b]quinazolines are readily oxidized on boiling in nitrobenzene, which leads to aromatization of the isoquino[3,2-b]quinazoline system to 5-methyl-13-oxo-5H,13H-isoquino[ 3,2-b]quinazolinium perchlorate and 6-benzyl-13H-isoquino[3,2-b]quinazolin-13-one. The structures of the dehydrogenation products were established from ¹H NMR and UV spectra. The interaction of the obtained compounds with NaBH₄ has been studied. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1833–1840, December, 2007.     

Reaction of 4-R-2-phenyltetrahydrobenzo[b]pyrylium and 9-R-sym-octahydroxanthylium salts with furfural and related compounds

The condensation of furfural, 5-methylfurfural, and 2-thiophenecarbaldehyde with 4-R-2-phenyltetrahydrobenzo[b]pyrylium and 9-R-sym-octahydroxanthylium salts was studied. Condensation conditions under which acidophobic aldehydes of the furan series do not undergo resinification were found. 8-Furfurylidene and 8-thenylidene derivatives of 4-R-2-phenyltetrahydrobenzo[b]pyrylium and bisfurfurylidene and bisthenylidene derivatives of 9-R-sym-octahydroxanthylium salts were obtained for the first time. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1160–1165, August, 2008.     

Planar beta-linked oligothiophenes based on thieno[3,2-b]thiophene and dithieno[3,2-b:2',3'-d]thiophene fused units

A series of planar beta-linked oligothiophenes based on thieno[3,2-b]thiophene and dithieno[3,2-b:2',3'-d]thiophene fused units were synthesized. The optical data indicate a blue shift of the absorption maximum in comparison to the alpha-linked analogues due to cross-conjugation between fused rings. The crystal structures of 3,3'-bi(thieno[3,2-b]thiophene) and 3,3';6',3"-ter(thieno-[3,2-b]thiophene) reveal edge-to-face pi-stacked dimer motifs, whereas the crystal structure of 3,3'-bis(dithieno[3,2-b:2',3'-d]thiophene) consists of face-to-face pi-stacked molecules. [structure: see text]     

Palladium-catalyzed reductive N-heterocyclization of alkenyl-substituted nitroarenes as a viable method for the preparation of bicyclic pyrrolo-fused heteroaromatic compounds

Palladium-catalyzed, carbon monoxide-mediated reductive N-heterocyclization of nitro-heteroaromatic compounds having an alkene adjacent to the nitro-group affords bicyclic pyrrolo-fused heteroaromatic molecules. This type of reaction was used to prepare the fused bicyclo[3.3.0] ring-system: thieno[3,2-b]pyrrole, thieno[2,3-b]pyrrole, furo[2,3-b]pyrrole, pyrrolo[3,2-d]thiazole, and pyrrolo[2,3-d]imidazole and the bicyclo[4.3.0] ring-systems: pyrrolo[3,2-b]pyridine, pyrrolo[2,3-b]pyridine, pyrrolo[3,2-c]pyridine, pyrrolo[2,3-c]pyridine, pyrrolo[3,2-c]pyridazine, and pyrrolo[3,2-d]pyrimidine in 32-94% yield.     

Electrophilic and nucleophilic substitution in oxazolo[3,2-f]xanthines

Bromination of 2-aryloxazolo[3,2-flxanthines gives the 3-bromoderivatives whereas 8-methyl-2-phenyloxazolo[3,2-f]xanthine is nitrated in the para-position of the phenyl substituent. Alkylation of oxazolo[3,2-f]xanthines by ethylmonoiodoacetate gives the ethyl esters of oxazolo[3,2-f]xanthinyl-6-acetic acids. Reaction of oxazolo[3,2-f]xanthines with sodium sulfide gives thiazolo[3,2-f]xanthines whereas the reaction with secondary amines opens the oxazole ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1396–1399, October, 1990.     

A simple one-pot synthesis of [1]benzotelluro[3,2-b][1]-benzotellurophenes and its selenium and sulfur analogues from 2,2′-dibromodiphenylacetylene

Treatment of 2, 2′-dibromodiphenylacetylene 7 with tert-butyllithium followed by tellurium insertion resulted in intramolecular ring closure to afford [1]benzotelluro[3,2-b][1]benzotellurophene 8a . Similarly, [1]benzoseleno-[3,2-b][1]benzoselenophene 8b and [1]benzothieno[3,2-b][1]benzothiophene 8c were also obtained.