Furan derivatives. Part 10. Synthesis of cyclohepta[cd]benzofuran

Cyclohepta[cd]benzofuran 2 was synthesized by heating (5-oxo-5H-benzocyclohepten-4-yloxy)acetic acid 16 with sodium acetate in acetic anhydride or by photocyclization of 16 in acetonitrile. Several reactions of cyclohepta[cd]benzofuran 2 were examined. Protonation of 2 with trifluoroacetic acid occurred at the 2-position to give a tropylium ion 17 . Catalytic hydrogenation of 2 with palladium on charcoal proceeded smoothly to give tetrahydrocyclohepta[cd]benzofuran 18 . The Diels-Alder reaction of 2 with tetracyano-ethylene produced an adduct 19 . Formylation of 2 with phosphorus oxychloride and dimethylformamide occurred easily at the 2-position to afford compound 20 . Cyclohepta[cd]benzofuran 2 has both properties of heptafulvene and benzofuran.     

Furan derivatives. Part 12 . Synthesis of 2,5-dioxacyclohepta[jkl]-as-indacenes

A variety of 2,5-dioxacyclohepta[jkl]-as-indacenes 5, 7–14 were synthesized as a new heterocycle by the treatment of diethyl (5,9-dioxobenzocyclohepten-1,4-diyloxy)diacetates 4a-e with potassium hydroxide or sodium hydride in dioxane. The mechanism of furan-ring formation from 4a-e was discussed.     

Furan derivatives. Part 9. Synthesis and properties of cyclohepta[cd]benzofurans

Cyclohepta[cd]benzofurans 1a-c were synthesized by heating (5-oxo-5H-benzocyclohepten-4-yloxy)acetic acids 7a-c with sodium acetate in acetic anhydride or by irradiation of 7a-c in acetonitrile. Several reactions such as protonation, catalytic hydrogenation, Diels-Alder reaction, acylation, and photoreaction were examined for 1a-b . The results show that cyclohepta[cd]benzofurans have both properties of heptafulvene and benzofuran. The carbon-carbon double bond in the furan ring of 1a has aromatic character, however, the carbon-carbon double bonds in the seven-membered ring have olefinic character.     

Synthesis of new azepino[3,4,5-cd]indole derivatives

New 2-oxoazepino[3,4,5-cd]indole derivatives were formed by the reaction of the tosylate SK&F 98339 with N-alkyl and N-arylidenepropylamines in moderate yield.     

Unexpected synthesis of azepino[4,3,2-cd]indoles from 4-aminoindoles

Unexpected regioselectivity for the Skraup-Doebner-Von Miller reaction was observed during the synthesis of quinolines from 4-aminoindoles and acetone in the presence of hydrochloric acid as a catalyst. The products were unambiguously assigned as 1-alkyl-3,5,5-trimethyl-5,6-dihydro-1H-azepino[4,3,2-cd]indoles instead of 2,2,4-trimethyl-2,7-dihydro-1H-pyrrolo[2,3-h]quinolones based on NMR spectroscopy and X-ray crystallographic analysis.     

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 thiopyrano[4,3-b]benzofurans

Representatives of a new heterocyclic system — thiopyrano[4,3-b]benzofuran — were synthesized by cyclization of the O-aryl ethers of tetrahydro-4-thiopyrone and 4-thiochromanone oximes in acid media.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 762–764, June, 1971.     

Synthesis of anthra[9,1-cd]isothiazolium derivatives and their reactions with nucleophiles

The methylation of 9-methyl-4-methylamino-5H-anthra[1,9,8-bcde]-1,10⁴-dithia-9-azapentalen-5-one takes place at the S₍₁₎, atom and leads to a 2-methyl-7-methylamino-10-methylthio-6-oxo-6H-anthra[9,1-cd]isothiazolium salt, while protonation is directed to the N₍₉₎ atom to give a 5,10-bis(methylamino)-6-oxo-6H-anthra [1,9-cd]dithiolium salt. Depending on their nature, substitution of the hydrogen atom in the 5 or 3 position, reversible addition of a hydroxide ion in the 10b position, demethylation, or opening of the heteroring occurs in the reaction of the anthraisothiazolium cation with nucleophilic reagents.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 256–263, February, 1992.     

Synthesis of spiro thiopyrano[2,3-d]thiazolidines

Spiro thiazolidine rings 3a,b are obtained in excellent yields by one-pot reaction of 1a,b with Lawesson reagent via [4 + 2] cycloaddition; the X-ray crystallography structure for compound 3a was determined and documented     

Octahydropyrrolo[4,3,2-m,n]acridine derivatives. I. Synthesis and molecular structure of derivatives of 2,3,4,5,7,8,9,10-octahydropyrrolo[4,3,2-m,n]acridin-10-one,a new heterocyclic system

Heating 1,1-bis(5,5-dimethyl-1,3-cyclohexanedion-2-yl)acetone with ammonia gave a new heterocyclic compound, namely, 1,4,4,8,8-pentamethyl-2,3,4,5,7,8,9,10-octahydropyrrolo[4,3,2-m,n]acridin-10-one. Analogously, 3,6-dimethyl-9-benzoyl-1,2,3,4,5,6,7,8-octahydroxanthene-1,8-dione gave 4,8-dimethyl-1-phenyl-2,3,4,-5,7,8,9,10-octahydropyrrolo[4,3,2-m,n]acridin-10-one. The structures of these products were demonstrated by PMR and IR spectroscopy and x-ray diffraction analysis.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 107–112, January, 1987.     

4-甲基吡咯并[2,1,5-cd]中氮茚的合成

以2-乙基吡啶生成的叶立德为原料,采用1,3-偶极环加成反应,得到了一系列3-乙酰基(或苯甲酰基)-5-乙基中氮茚衍生物,后者与KOH在加热条件下发生分子内缩合,得到了一系列4-甲基吡咯并[2,1,5-cd]中氮茚.     

Selenium heterocycles XXVI. Synthesis of theino[3,4-b]benzofuran and selenolo[3,4-b] benzofuran. Two novel heterocycles

Starting from the readily available aryl 3-methyl-2-benzo[b] furyl ketones a series of 3-sub-stituted thieno[3,4-b] benzofurans and 3-substituted selenolo[3,4-b] benzofurans were prepared in high yield. The parent compound, thieno[3,4-b] benzofuran was prepared through the reaction of thioacetamide with 2-chloromethyl-3-formylbenzo[b] furan in moderate yield.     

Solvent-free combinatorial synthesis of tetrazolo[1,5-a]thiopyrano[3,4-d]pyrimidine derivatives

A series of novel tetrazolo[1,5-a]thiopyrano[3,4-d]pyrimidine derivatives were synthesized by reaction of aryl aldehyde, 2H-thiopyran-3,5(4H,6H)-dione, and 5-aminotetrazole under solvent-free conditions. The features of this procedure are mild reaction conditions, high yields, and operational simplicity.     

Synthesis of derivatives of tetrazolo[1,5-a]- and oxazolo[4,5-b]pyrano(thiopyrano)[3,4-c]pyridines

Tetrazolo[1,5-a]- and oxazolo[4,5-b]pyrano(thiopyrano)[3,4-c]pyridines, which are new heterocyclic systems, have been synthesized from pyrano[3,4-c]pyridine derivatives.A. L. Mndzhoyan Institute of Fine Organic Chemistry, Armenian Academy of Sciences, Yerevan 375014. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1260–1262, September, 1997.     

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.     

v-triazolines. Part XVI. Synthesis of benzothiepino[4,5-d]-v-triazole derivatives

The cycloaddition reaction of some arylazides to enamines 4a-f afforded v-triazolines 5a-i ; by subsequent acid-catalyzed hydrolysis v-triazoles 6a-c were obtained. The reversibility of the cycloaddition was demonstrated on the basis of spectroscopic or chemical evidences.     

Synthesis of thiopyrano[2,3-d] pyrimidines and thieno[2,3-d]pyrimidines

The reaction of 4-chloro-5-cyano-2-methylthiopyrimidine (I) with ethyl mercaptosuccinate (II) in refluxing ethanol containing sodium carbonate has afforded diethyl 3-amino-2-(methyl-thio)-7H-thiopyrano[2,3-d]pyrimidine-6,7-dicarboxylate (IV). Displacement of the methylthio group in IV with hydrazine gave the corresponding hydrazino derivative which underwent Schiff base formation with benzaldehyde or 2,6-dichlorobenzaldehyde. Treatment of IV in refluxing acetic anhydride afforded the corresponding diacetylated amino derivative. Partial saponification of IV with sodium hydroxide gave 5-amino-2-(methylthio)-7H-thiopyrano-[2,3-d]pyrimidine 6,7-dicarboxylic acid 6 ethyl ester (VIII). The reaction of 4-amino-6-chloro-5-cyano-2-phenylpyrirnidine (XI) with II resulted in the formation of ethyl 4-amino-6-(ethoxy-carbonyl)-5,6-dihydro-5-amino-2-phenylthieno[2,3-d]pyrimidine-6-acetate (XIII) which when subjected to hydrolysis gave ethyl 4,5-diamino-2-phenylthieno[2,3-d]pyrimidine-6-acetate isolated as the hydrochloride (XIV). Diazotization of IV with sodium nitrite in acetic acid unexpectedly afforded diethyl 5-(acetyloxy)-6,7-dihydro-6-hydroxy-2-(methylthio)-5H-thio-pyrano[2,3-d]pyrimidine-6,7-diearboxylate (XV). Several structural ambiguities were resolved by ir and pmr spectra.     

Synthesis of 6H-Naphtho[1,2,3-cd]indol-6-ones

S,S-Dimethyl-and S-methyl-S-phenyl-N-(9,10-anthraquinon-1-yl)sulfoximides are converted into 6H-naphtho[1,2,3-cd]indol-6-ones on heating in polar aprotic solvents.     

Synthesis and properties of furo[4,3,2-de][1]benzopyran

A new heterocycle, furo[4,3,2-de][1]benzopyran ( 2 ), was synthesized. A key step in the sequence was the allylic bromination of 3,4-dihydrofuro[4,3,2-de][1]benzopyran ( 8 ) to give 3-bromo-3,4-dihydrofuro[4,3,2-de][1]-benzopyran ( 10 ) using N-bromosuccinimide under irradiation and high dilution conditions. Bromide 10 was dealt with 1,8-diazabicyclo[5.4.0]undec-7-ene to afford compound 2 . Several reactions of 2 were examined. Protonation of 2 in trifluoroacetic acid occurred at the 2-position to form a pyrylium ion 12 . Catalytic hydrogenation of 2 with palladium on charcoal proceeded smoothly to give 8 . Reduction of 2 by sodium and ethanol afforded 3-ethyl-4-hydroxybenzofuran ( 14 ). Electrophilic substitutions of 2 such as formylation, acetylation, and bromination, occurred easily at the 2-position. The above results show that compound 2 has both properties of benzofuran and 4-methylenepyran.