Synthesis of benzothiopyrano[4,3,2-de]quinoline

[1]Benzothiopyrano[4,3,2-de]quinoline ( 13 ), a novel tetracyclic compound without substituents on the ring has been synthesized from 1-amino-9H-thioxanthen-9-one ( 4 ) via 1-ethoxycarbonylacetamido)-9H-thioxanthen-9-one ( 7 ) in six steps.     

Synthesis of pyrido[4,3,2-de]quinazolines via nitro-substituted tetrahydroquinolines

The simple and efficient synthesis of novel dihydropyrido[4,3,2-de]quinazolines in four steps from m-nitroaniline is described.     

A new synthesis of benzothiopyrano[4,3,2-de]quinazolines

The synthesis of benzothiopyrano[4,3,2-de]quinazolines ( 1a-c ) from 1-chloro-4-methylthioxanthone is described.     

Synthesis of substituted furo[3,2-e][1,2,4]triazolo[4,3-c]pyrimidines and furo[3,2-e]tetrazolo[1,5-c]pyrimidines

A series of substituted furo[3,2-e][1,2,4]triazolo[4,3-c]pyrimidines and furo[3,2-e]tetrazolo[1,5-c]pyrimidines were obtained from reactions of substituted 2-dimemylamino-4-hydrazmofuro[2,3-d]pyrimidines with orthoesters or sodium nitrite in acetic acid, respectively.     

Amidomethylation of indoles and cyclisations to spiro[pyrrolo[4,3,2-de]isoquinoline-3,4′-piperidines]

4-Aminomethylindoles react with aldehydes and ketones to form pyrrolo[4,3,2-de]isoquinolines. The structures of starting materials and end products were determined using 1D and 2D ¹H nmr techniques.     

Synthesis of the novel thieno[4,3,2-ef][1,4]benzoxazepine ring system: 4,5-Dihydro-3-(4-pyridinyl)thieno[4,3,2-ef][1,4]benzox-azepine maleate

4,5-Dihydro-3-(4-pyridinyl)-thieno[4,3,2-ef][1,4]benzoxazepine maleate 2 has been synthesized from 3-amino-4-fluorobenzo[fc]thiophene by employing an intramolecular nucleophilic aromatic fluoride displacement. In the presence of strong base and heat, 2 rearranges to form the isomeric hemiaminal, 3,4-dihydro-4-methyl-3-(4-pyridinyl)thieno[4,3,2-ef][1,3]benzoxazine 10 . A proposed mechanism for this rearrangement is discussed.     

Synthesis and reactivity of furo[2,3-e]pyrrolo[1,2-a][1,4]diazepin-9-one

A convenient method for the synthesis of furo[2,3-e]pyrrolo[1,2-a][1,4]diazepin-9-one is described. It has been C-alkylated with amine (piperidine, morpholine, 4-methylpiperazine) and N-alkylated with alkyl halides (methyl iodide and benzyl chloride).     

Synthesis of substituted 1,4-diazepino[5,6,7-kl]acridines and imidazo[4,5,1-de][1,4]diazepino[5,6,7-mn]acridines

The synthesis of some substituted ll-methoxy-7-nitro-4H,8H-2,3-dihydro-1,4-diazepino[5,6,7-kl]acridines 4 with more diversified chains at position 4 is described. A convenient method for transformation of these compounds into the corresponding 4-substituted 12-methoxy-4H-2,3-dihydroimidazo[4,5,1-de][1,4]diazepino-[5,6,7-mn]acridine (5) is reported.     

Synthesis and mesomorphic properties of liquid crystalline [1]benzothieno[3,2-b][1]benzothiophene derivatives

Two new series of chiral aliphatic and aromatic esters of 7-decyl[1]benzothieno[3,2-b][1]benzothiophene-2-carboxylic acid were synthesized and their mesomorphic behaviour studied. While the chiral aliphatic esters exhibited only the SmA phase, the antiferroelectric SmC_A* phase was found for esters with chiral 4-hydroxybenzoates; for one homologue a ferroelectric SmC* phase was also observed. Introduction of lateral substituents in the 3-position of the 4-hydroxybenzoic acids (methoxy, fluoro, chloro, and bromo) led to a reduction of the polymorphism and only the SmA phase remained.     

Oxidative Cyclization of 5H-Chromeno[2,3-b]pyridines to Benzo[b]chromeno[4,3,2-de][1,6]naphthyridines,Their NMR Study and Computer Evaluation as Material for LED

Oxidative cyclization is one of the most significant reactions in organic synthesis. Naphthyridine derivatives are often used as luminescence materials in molecular recognition because of their rigid planar structure and as new drugs. Organic light-emitting diodes (OLEDs) have rapidly grown as one of the leading technologies for full-color display panels and eco-friendly lighting sources. In this work, we propose the synthesis of previously unknown benzo[b]chromeno[4,3,2-de][1,6]naphthyridines via intermolecular oxidative cyclization of 5-(2-hydroxy-6-oxocyclohexyl)-5H-chromeno[2,3-b]pyridines in formic acid. The investigation of the reaction mechanism using ¹H-NMR monitoring made it possible to confirm the proposed mechanism of the transformation. The structure of synthesized benzo[b]chromeno[4,3,2-de][1,6]naphthyridines was confirmed by 2D-NMR spectroscopy. Such a rigid geometry of synthesized compounds is desired to minimize non-radiative energy losses in OLEDs. The quantum chemical calculations are also presented in the study.     

Synthesis of furo[2,3-f]- and furo[3,2-e]indole derivatives

Two compounds — the diethylamides of 1,2-dimethyl-3-carbethoxy-6-carboxyfuro[2,3-f]- and 1,2-dimethyl-3-carbethoxy-5-carboxvfuro[3,2-e]indoles — are formed in the reaction of 1,2-dimethyl-3-carbethoxy-5-hydroxyacetic acid (I) with dimethylformamide and phosphorus oxychloride as a result of subsequent intramolecular cyclization of the intermediates. This constitutes evidence for formylation of the starting acid in the 6 and 4 positions. Formylation of the ethyl ester of acid I gives only the 6-formyl derivative, the intramolecular cyclization of which under the influence of sodium ethoxide gives 1,2-dimethyl-3,6-dicarbethoxyfuro[2,3-f]-indole. Hydrolysis of the latter with alcoholic alkali gives the corresponding dicarboxylic acid. The structures of the synthesized compounds were confirmed by the PMR, IR, and mass spectra.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 766–769, June, 1977.     

Condensation reactions of 3-Amino-4-imino-4H-thieno-[3,4-c][1]benzopyran

The title compound 1 reacts with trifluoroacetic anhydride to give the doubly trifluoracetylated derivative 2 and in addition the coumarin derivative 3 . In refluxing DMF, two moles of 1 react with loss of one molecule of ammonia to afford 4 , which undergoes subsequent N-acylation by β-dicarbonyl compounds 9a-f to yield N-acyl derivatives 10a-f . With dimethyl malonate ( 9a ) besides compound 10a , the cycloacylated compound 11 was also obtained in good yield. Compound 11 is readily hydrolysed and decarboxylated with both acid and alkali to the previously described fused derivative 12 . The latter may be converted into the new thienopyrimidinone derivative by action of aqueous alkali.     

Synthesis of New Pyrazolo[1.5.4-de]quinoxalines

New pyrazolo[1.5.4-de]quinoxaline derivatives were prepared by the action of 7-aminoindazole 1 on diethyl and dimethyl acetylene dicarboxylates. The structures of the obtained compounds and the direction of cyclization were investigated through a crystallographic study of compound 2. Further alkylation, hydrogenation, and bromination were also explored. The action of potassium thiocyanate on the obtained halo product led to a tetracyclic compound of 1.3-thiazolo[3.4-a]pyrazolo[1.5.4-de]quinoxaline series.     

Thiophene systems. 11. The synthesis of novel thieno[4,3,2-de] tricyclic ring systems

The synthesis of thieno[4,3,2-de] tricyclic compounds is described. The N-1 alkylation of I produced the alkanoic ester precursors. After hydrolysis, the corresponding carboxylic acids were cyclized to the title compounds II . This cyclization step was accomplished with 1:10 phosphorus pentoxide-methanesulfonic acid. The ketones II were further modified to introduce additional functionality onto this novel tricyclic ring system.     

Synthesis of furo[b]tropylium tetrafluoroborate

The first synthesis and characterization of the title compound are described.     

Synthesis of furo[2,3-b]pyridine

Two routes were employed to synthesize unsubstituted furo[2,3-b]pyridine (IV). The first method started with ethyl 5-aminofuro[2,3-b] pyridine-2-carboxylate (1) and involved successive deamination, hydrolysis, and decarboxylation. The second method began with 5-nitrofuro[2,3-b ]-pyridine-2-carboxylic acid (V) and consisted of successive decarboxylation, reduction, and deamination reactions.