Oxidative coupling in 4a,9-diaza-1,2,4a,9a-tetrahydrofluorene derivatives. 2. Synthesis of methylenequinoneimines

The oxidative coupling of 4a,9-diaza-1,2,4a,9a-tetrahydro-9H-fluorene derivatives with methylene-active compounds in the presence of MnO₂ leads to substituted (at the methylene group) 6-methylene-4a,9-diaza-1,2,4a,9a-tetrahydro-6H-fluorene derivatives. The corresponding 2,2-disubstituted 5-dicyanomethylene-3,5-dihydrobenzimidozoles were obtained in the reaction of 2,2-disubstituted benzimidazolines with malonitrile in the presence of MnO₂.See [1] for Communication 1.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 779–785, June, 1990.     

Oxidative Coupling in a Series of Derivatives of 4a,9-Diaza-1,2,4a,9a-tetrahydrofluorene. 6. Reactions with Substituted 2-Aminoethanols

Oxidative coupling of derivatives of 4a,9-diaza-1,2,4a,9a-tetrahydro-9H-fluorene with 2-ethyl-, 2,2-dimethyl-, and 2-hydroxymethyl-2-methylaminoethanol in the presence of MnO₂ led to the selective formation of the corresponding mono- and di(hydroxymethyl)quinonediimines, subsequent cyclization of which gave the products of 6,7-annelation. Coupling with 2,2-di(hydroxymethyl)aminoethanol gave the annelation products directly.     

Synthesis of polynuclear heterocyclic quinone imines — Derivatives of 4a,9-diazahydrofluoren-6-ones

When derivatives of 4a-9-diaza-1,2,4a,9a-tetrahydrofluorene are oxidized by treatment with MnO₂, the corresponding derivatives of 4a,9-diaza-1,2,4a,9a-tetrahydrofluoren-6-one are obtained. In a number of cases the reaction is accompanied by dehydrogenation of the side chains as well as the diazahydrofluorene fragment.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 793–798, June, 1988.     

Oxidative Coupling of 4α,9-Diaza-1,2,4α,9α-tetrahydrofluorenes. 5. Reaction with o-Aminophenol and o-Aminothiophenol

Oxidative coupling of 4,9-diaza-1,2,4,9-tetrahydro-9H-fluorenes with o-aminophenol and o-aminothiophenol in the presence of MnO₂ gives o-hydroxyphenyl- and o-mercaptophenylquinonediimines, cyclization of which gives derivatives of phenoxazine and phenothiazine.     

Reactions of derivatives of 4a,9-diaza-1,2,4a,9a-tetrahydro-6H-fluorene with nucleophilic reagents and bromine

The reaction of quinone mono- and diimines of the 4a,9-diaza-12,4a,9a-tetrahydro-6H-fluorene series with aniline and thiophenol gives the corresponding 7-monosubstituted derivatives; with o-phenylenediamine and o-aminophenol the corresponding 6,7-annellated products are formed. Methylenequinone imines of this series, and also the 7,8-benzannellated analogs ofdiazahydrofluorenes, do not react with these nucleophiles. The bromination of diazahydrofluorene derivatives involves both the quinoid system and the enamine fragment.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 982–989, July, 1991.     

Synthesis of 9-alkylidene-9H-fluorenes by a novel, palladium-catalyzed cascade reaction of aryl halides and 1-aryl-1-alkynes.

In the presence of a palladium catalyst and NaOAc, aryl iodides react with 1-aryl-1-alkynes to afford 9-alkylidene-9H-fluorenes in good yields. The products from this reaction are highly dependent on the base employed. This process appears to involve (1) oxidative addition of the aryl iodide to Pd(0), (2) alkyne insertion, (3) rearrangement of the resulting vinylic palladium intermediate to an arylpalladium species, and (4) aryl-aryl coupling with simultaneous regeneration of the Pd(0) catalyst. Consistent with this mechanism is the fact that 9-alkylidene-9H-fluorenes can also be prepared by the Pd-catalyzed rearrangement of 1,1-diaryl-2-iodo-1-alkenes.     

Reaction of 1,2-diamino-4-nitrobenzene with 1,5-diketones. Synthesis and oxidative reactions of nitrobenzimidazoles

Reaction of 1,5-diketones with 1,2-diamino-4-nitrobenzene gave a mixture of the 6- and 7-nitro derivatives of 4a,9-diaza-1,2,4a,9a-tetrahydrofluorene. Oxidation of the 6-nitro derivatives with MnO₂ gives para-quinone imines with elimination of the nitro groups. Oxidation of the 7-nitro derivative and oxidative conjugation of 5-nitro-2,2-pentamethylene-1,2-dihydrobenzimidazole with primary amines in the presence of MnO₂ gives nitro ortho-quinone imines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 927–930, July, 1990.     

Synthesis of 9-alkylidene-9H-fluorenes by a novel palladium-catalyzed rearrangement

In the presence of a palladium catalyst and NaOAc, aryl iodides react with 1-aryl-1-alkynes to afford 9-alkylidene-9H-fluorenes in good yields. This process appears to involve (1) oxidative addition of the aryl iodide to Pd(0), (2) alkyne insertion, (3) rearrangement of the resulting vinylic palladium intermediate to an arylpalladium species, and (4) aryl-aryl coupling with simultaneous regeneration of the Pd(0) catalyst.     

The synthesis of 3,4,4a,9a-tetrahydro-2(1H)-carbazolones

Cyclization of 4-(1-methylindol-3-yl)-2-butanone and the corresponding 1-benzyl analog in trifluoroacetic acid furnishes 9-methyl- and 9-benzyl-3,4,4a,9a-tetrahydro-2(1H)-carbazolone, respectively. Under the same conditions, 4-(indol-3-yl)-2-butanone gives the dimer, 3-(3-oxo-butyl)-2-[3-(3-oxobutyl)-2-indolinyl] indole. When boron trifluoride etherate is used instead of trifluoroacetic acid, the desired 3,4,4a,9a-tetrahydro-2(1H)-carbazolone is obtained. The determination of the structure of the tetrahydrocarbazolones is described and the stereochemistry of the ring fusion is discussed.     

Cyclocondensation of 6-acetyl-4,7-dihydro-5-methyl-7-phenyl[1,2,4]triazolo[1,5-a]pyrimidine with hydroxylamine and hydrazine

The cyclocondensation of 6-acetyl-4,7-dihydro-5-methyl-7-phenyl[1,2,4]triazolo[1,5-a]pyrimidine (3) with hydroxylamine or hydrazine leads to 3a,4,9,9a-tetrahydro-3,9a-dimethyl-4-phenylisoxazolo-[5,4-d][1,2,4]triazolo[1,5-a]pyrimidine ( 4a ) and 3a,4,9,9a-tetrahydro-3,9a-dimethyl-4-phenyl-1H-pyrazolo[3,4-d][1,2,4]triazolo[1,5-a]pyrimidine ( 4b ), respectively. In the presence of methanolic hydrogen chloride, 4b undergoes a cleavage of the pyrimidine ring to yield (5-amino-1,2,4-triazol-1-yl)(3,5-dimethylpyrazol-4-yl)phenylmethane ( 5 ). The structure determination of the compounds obtained is based on ¹H and ¹³C nmr spectra including NOE measurements.     

Synthesis of 1- and 2-Carbamoylalkyl-2,3-dihydro-1H-indole and 9-Carbamoylalkyl-2,3,4,4a,9,9a-hexahydro-1H-carbazole Derivatives

Treatment of 1,2,3,9a-tetrahydro-9H-imidazo- and 1,2,3,4,10,10a-hexahydropyrimido[1,2-a]indol-2-one derivatives with formic acid gave 1-carbamoylalkyl-2,3,3-trimethyl-2,3-dihydro-1H-indoles. 9-Carbamoylmethyl- and 9-(2-carbamoylethyl)-4a-methyl-2,3,4,4a,9,9a-hexahydro-1H-carbazoles were prepared from 5,6,7,7a-tetrahydro-1H,4H-imidazo- and 1,2,6,7,8,8a-hexahydro-5H-pyrimido[2,1-k]carbazolones in a similar manner. Synthesis of 2-(2-carbamoylpropyl)-2,3,3-trimethyl-2,3-dihydro-1H-indole was carried out by reduction of 1,3-dihydrospiro[2H-indolo-2,2'-piperidine] derivative with Zn in acetic acid solution.     

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.     

Annelation of lactam rings to 2,3,4,4a-tetrahydro-1H-carbazole derivatives

In the reaction of 4a-methyl-2,3,4,4a-tetrahydro-1H-carbazole and its 6-methyl- and 6-bromosubstituted derivatives with 2-chloroacetamide respectively by 9-carbamoylmethyl-4a-methyl-2,3,4,4a-tetrahydro-1H-carbazolium chlorides are formed, which can be cyclized into 5,6,7,7a-tetrahydro-1H, 4H-imidazo[2,1-k]-carbazol-2(3H)-one derivatives. Reaction of 4a-methyl-2,3,4,4a-tetrahydro-1H-carbazole hydrochloride with acrylamide gives 8a-methyl-1,2,6,7,8,8a-hexahydro-5H-pyrimido[2,1-k]carbazol-3(4H)-one. 7a, 12-Dimethyl-3,4,4a,5,6,7,7a,12-octahydropyrido[3,2-j]carbazol-2(1H)-one was synthesized by the reaction of 4a,9-dimethyl-2,3,4,4a-tetrahydro-9H-carbazole with acrylamide. Department of Organic Chemistry, Kaunas University of Technology, Kaunas LT-3028, Lithuania; Published in Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 645–648, May 1999.     

Photochemistry of phenyl-substituted 1,2,4-thiadiazoles. 15N-labeling studies

Irradiation of 5-phenyl-1,2,4-thiadiazole (6) resulted in the formation of benzonitrile (5), 3-phenyl-1,2,4-thiadiazole (4), phenyl- and diphenyl-1,3,5-triazines (7 and 8), and a trace quantity of diphenyl-1,2,4-thiadiazole (9). The formation of 4,5, 7, and 8 can be explained in terms of photoinduced electrocyclic ring closure resulting in the formation of an intermediate 4-phenyl-1,3-diaza-5-thiabicyclo[2.1.0]pentene. 15N-labeling experiments revealed that sulfur can undergo sigmatropic shifts around all four sides of the diazetine ring. Thus, irradiation of 6-4-15N led to the formation of 6-2-15N and an equimolar mixture of 4-2-15N and 4-4-15N. The thiabicyclo[2.1.0]pentene intermediate is also suggested to undergo sulfur elimination resulting in the formation of phenyldiazacyclobutadiene, which can undergo complete fragmentation to benzonitrile or [4+2] cycloaddition leading to unstable tricyclic adducts, the suggested precursors of the 1,3,5-triazine products 7 and 8. The observed 15N distribution in 7 and 8 is consistent with this mechanism. Irradiation of 4 led only to the formation of 5. 15N-labeling experiments show that 4 does not undergo electrocyclic ring closure but reacts exclusively by photofragmentation of the thiadiazole ring.     

The Synthesis of 4b, 5, 12, 12a-Tetrahydro-5, 12-ethano-13H-indeno[2,3-b]anthracenes, 4b, 5, 10, 10a - tetrahydro-5,10-ethano-11H-indeno[2,3-b]naphtalenes and 1,2,3,4,4a, 9a-Hexahydro-1,4-(peri-naphthaleno)-fluorenes

The synthesis of endo- and exo-13-oxo-4b, 5, 12, 12a-tetrahydro-5, 12-ethanoindeno[2,3-b]anthracene ( 23 ; Schemes 1 and 2), exo- and endo-11-oxo-4b, 5, 10, 10a-tetrahydro-5, 10-ethano-indeno[2,3-b]naphthalene ( 31 ; Scheme 3), 1,2,3,4,4a,9a-hexahydro?1,4-(peri-naphthaleno)-fluoren-9-one (36; Scheme 4), and the corresponding hydrocarbons of the stereoisomeric ketone pairs 23 and 36 , is described.     

Unexpected formation of clusters with a nortricyclene-containing carborane ligand, 1-(η6-arene)-3-(C7H9CH2O)-isonido-1,2,4-RuC2B8H9, in the reaction of 1,1,3-(PPh3)3-1-H-1,2,4-RuC2B8H9 with 2-(hydroxymethyl)norbornadiene in arene solvents

Heating of 1,1,3-(PPh₃)₃-1-H-1,2,4-RuC₂B₈H₉ with 2-(hydroxymethyl)bicyclo[2.2.1]hepta-2,5-diene in arene solvents (benzene, toluene, or mesitylene) unexpectedly afforded the ruthenium arene complexes 1-(η⁶-arene)-3-(C₇H₉CH₂O)-isonido-1,2,4-RuC₂B₈H₉ containing the nortricyclene fragment in the carborane ligand.     

Intramolecular Oxygen Transfer on the Ozonolysis of a Diphenylcyclopentene Derivative

The ozonolysis of cis-3,4a,7,7a-tetrahydro-3,3-dimethyl-6,7a-diphenylcyclopenta[1,2,4]trioxine ( 1 ) in CH₂Cl₂ at ?78° gave the secondary endo ozonide 2 (43% yield) and an acetal 3 (27% yield) derived from O-insertion at the ortho position of the C(7a) phenyl substituent. Both structures were elucidated by X-ray. Repetition of the ozonolysis in MeOH/CH₂Cl₂20:3 at ?78° also gave the same two products in 12 and 15% yields, repectively, together with the hemiperacetal 4 (54% yield) formally derived from the secondary ozonide by addition of MeOH.     

Arylation,alkylation, reduction,and pyrolysis of 1h-1-methylindeno[2,1-b]pyridine

Nucleophilic substitution (phenylation with phenyl lithium) of 1H-1-methylindeno[2,1-fa]pyridine occurred at the C₍₂₎ and C₍₄₎ positions, and electrophilic substitution (methylation and benzylation with halogen derivatives) at C₍₉₎. Reduction of the starting anhydrobases gave 1-methyl-1,2,3,9a-tetrahydro-1-azafluorene, and pyrolysis gave 1-azafluorene and 1-azafluorenone.Translated from Khimiya Geterotsiklicheskikn Soedinenii, No. 9, pp. 1212–1214, September, 1986.     

1, 9-substituted fluorenes

Syntheses of 3-chloropyridazino[4, 5, 6-m, l]fluorene and its 9-methyl and 9-chloro derivatives are described. Products in which a chlorine atom of these compounds is exchanged with NH₃, C₆H₅NH₂, NH₂ · NH₂, H₂O, C₆H₅NHNH₂, CH₃ONa, and compounds containing an active methylene group are prepared. Treatment of 3-hydrazinopyridazino[4, 5, 6-m, 1]fluorene and 3-hydrazino-9-methylpyridazino[4, 5, 6-m, 1]fluorene with alcoholic alkali and HgO give respectively pyridazino[4, 5, 6-m, 1]fluorene and 9-methylpyridazino[4, 5, 6-m, 1]fluorene, while 3-phenylhydrazinopyridazino[4, 5, 6-m, 1]fluorene is oxidized under the same conditions to 3-phenylazopyridazino[4, 5, 6-m, 1]fluorene.For Part II see [1].     

A simple and efficient synthesis of enantiomeric (3aRS,4RS,6aSR)-4-hydroxy-3,3a,4,6a-tetrahydro-1H-cyclopenta[c]furan-1-ones

Diastereomeric amides produced via the cleavage of easily available (±)-7,7-dichloro-4-exo-trimethylsilylbicyclo[3.2.0]hept-2-en-6-one by treatment with (+)-α-methylbenzylamine were transformed into bicyclic lactam-aminals, which can easily be separated by column chromatography on SiO₂. The latter products lead to enantiomeric (3a,6a)-4-hydroxy-3,3a,4,6a-tetrahydro-1H-cyclopenta[c]furan-1-ones after the removal of the chiral auxiliary and epoxidation.