Synthesis of unsaturated derivatives of 2,5-dimethyl-4-phenylpyridine and 3-methyl-2-azafluorene

A substituted butadiene — 1-phenyl-4-(5-methyl-4-phenyl-2-pyridyl)buta-1,3-diene with a trans, trans configuration — was obtained by condensation of 2,5-dimethyl-4-phenylpyridine with cinnamaldehyde. Two 3-methyl-9-cinnamylidene-2-azafluorene isomers are formed as a result of condensation of the same aldehyde with 3-methyl-2-azafluorene. Data from the PMR and IR spectra were used to prove the configuration of the compounds obtained. It was established that the condensation of 3-methyl-2-azafluorene with salicylaldehyde gives 3-methyl-9-(2-hydroxybenzylidene)-2-azafluorene, which has a zwitterionic structure, and 1,2-bis(3-methyl-2-aza-9-fluorenylidene)ethane. Ideas regarding the chemical mechanism of the formation of the latter are presented. The preparation of an unsaturated alcohol — 3-methyl-9-allyl-2-aza-9-fluorenol — is described.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 82–86, January, 1978.     

Synthesis of 3-alkyl-2, 4, 6-triphenylpyridines and 1,3-diphenyl-4- and-2-azafluorenes

The previously unknown 3-alkyl-2,4,6-triphenylpyridines were obtained from 1-methyl-3-alkyl-2, 6-diphenyl-4-piperidones. It was established that a mixture of 1,3-diphenyl-4-azafluorene and 1,3-diphenyl-2-azafluorene is formed in the dehydrocyclization of 3-methyl-2,4,6-triphenylpyridine.     

9-Acyl- and 9-aroyl-3-methyl-2-azafluorenes

The condensation of 3-methyl-2-azafluorene with esters of aromatic and aliphatic acids has given 9-aroyl and 9-acyl derivatives of 2-azafluorene. They are stable in the enolic form. The 9-benzoyl derivative (II) has also been isolated in the oxo form. The transition from (II) to the cis-trans isomers of 9-benzylidene-3-methyl-2-azafluorene has been effected.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 986–989, July, 1973.     

Synthesis of spiro compounds with 3-methyl-2-azafluorene,indan, pyrazoline,and cyclopropane fragments on the basis of 3-methyl-9-phenylethynyl-2-azafluoren-9-ol

3-Methyl-9-phenylethynyl-2-azafluoren-9-ol, 3-methyl-9-phenacylidene-2-azafluorene, and spiro compounds with 2-azafluorene, indan, pyrazoline, and cyclopropane fragments were obtained starting from 3-methyl-2-azafluorenone by successive transformations. Information regarding the spatial structures of the synthesized compounds was obtained.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 539–541, April, 1985.     

3-Methyl-9-benzylidene-2-azafluorene and its analogs

The possibility of obtaining 3-methyl-2-azafluorene by dehydrocyclization of 2,5-dimethyl-4-phenylpyridine at 500–750° in the absence of a catalyst was examined. This azafluorene was condensed with aromatic aldehydes. Several transformations of the geometrical isomers of 3-methyl-9-benzylidene-2-azafluorene and its analogs were studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1398–1402, October, 1971.     

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.     

Synthesis of phenyl(benzyl)-substituted (in the pyridine ring) azafluorenes

Phenyl and benzyl groups were introduced in the 1 position of 3-methyl-2-azafluorene by treatment of it or its N-oxide with organometallic compounds. 1-Phenyl-substituted 2-azafluorene was also obtained by catalytic dehydrocyclization of 2,5-dimethyl-4,6-diphenylpyridine, during which the simultaneous formation of the isomeric 4-azafluorene was established.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 124–126, January, 1977.     

Synthesis and transformations of 1-methyl-4-azafluorene

By means of catalytic dehydrocyclization of dimethyl-substituted 2-phenylpyridines in a pyridine ring to 1(2,3)methyl-4-azafluorenes with subsequent oxidation, synthesis of alkaloid onychine — 1-methyl-4-azafluorene — several of its isomers were achieved. Using 1-methyl-4-azafluorene, we obtained a C₉ furfurylidene product, substituted tetrahydroindine[1,2-b]pyridine and NH-indine[1,2-b]-pyridine. We obtained 7-nitro-1-methyl-4azafluorene by nitration of onychine and oxidation of nitro-substituted azafluorene; this indicates an identical orientation of 4-azafluoren(one) and fluoren(one) during nitration.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 513–517, April, 1982.     

Synthesis of substituted indano[2,1-c]piperidines

Substituted indano[2,1-c]piperidines were obtained by selective hydrogenation over Re₂S₇ and also by reduction with sodium in alcohol of 3-methyl-2-azafluorene and its derivatives. The geometrical isomers of the products were isolated and characterized.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1379–1383, October, 1973.     

Transformations of 3-methyl-2-azafluorene involving the methyl and methylene groups

The condensation of 3-methyl-2-azafluorene with benzaldehyde at the methyl group, as a result of which the cis and trans forms of 3-styryl-2-azafluorene are formed, proceeds without catalysts. The subsequent condensation with benzaldehyde takes place in the presence of potassium ethoxide and leads to 3-styryl-9-benzylidene-2-azafluorene. Treatment of azafluorene with phenoxyacetyl chloride in the presence of triethylamine yielded 3-methyl-9-(-hydroxy--phenoxyethylidene)-2-azafluorene. On the basis of the spectral data it was concluded that the latter exists in the form of a mixture of the enol form and the zwitterionic form. 3-Methyl-9-(-phenyl--cinnamoyloxyallylidene)-2-azafluorene was obtained by acylation of azafluorene with cinnamoyl chloride under the same conditions. The PMR and IR spectral data are presented.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 79–81, January, 1978.     

Indenyl and fluorenyl transition metal complexes.: IV. Reactions of 2- and 4-azafluorenes with chromium hexacarbonyl

Reactions of 2- and 4-azafluorenes (I, II) and their methyl derivatives, 3-methyl-2-azafluorene (III) and 7-methyl-4-azafluorene (IV) with chromium hexacarbonyl in a $\text{1}\text{1}$ diglyme/heptane mixture at 140°C have been studied. A N-donor complex, C₁₂H₉NCr(CO)₅ is formed in the reaction of I with Cr(CO)₆. Compounds II–IV react to give arenechromiumtricarbonyl derivatives with benzene rather than pyridine ring bound to the metal. [η⁶-(4b,5,6,7,8,9b)-4-Azafluorene]chromiumtricarbonyl (VIII) gives the corresponding hydrochloride under the action of HCl. Methyl iodide decomposes VIII to produce 4-azafluorene iodomethylate. Deprotonation of VIII with BuLi in ether at ?20°C followed by dilution with hexane leads to precipitation of the corresponding Li salt (Xb), having η⁶-structure. Methylation of Xb with methyl iodide proceeds stereospecifically to yield the exo-methyl derivative XII. Treatment of VIII with excess t-BuOK at 25°C in THF results in a mixture of η⁶-(Xa) and η⁵-anions (XI), the former predominating.     

Benzopyridofulvenes

A group of benzopyridofulvenes was obtained by condensation of 3-methyl-2-azafluorene and 4-azafluorene with anisaldehyde, veratraldehyde, and p-nitrobenzaldehyde. It was established that they are produced in the form of geometrical isomers, which could be isolated in the case of the 9-(o-methoxy) and 9-(m,p-dimethoxy) derivatives of 3-methyl-2-azafluorene. One isomer of the analogous benzylidene derivative and 3-[-hydroxy--(p-nitrophenyl)ethyl]-2-azafluorenone were obtained in the condensation of this azafluorene with p-nitrobenzaldehyde. The dimethoxybenzylidene derivatives of both azafluorenes were reduced to dimethoxybenzyl derivatives. The geometrical isomers of a substituted indenoindolizine were obtained from the mixture of isomers of N-phenacyl-9-(m,p-dimethoxybenzylidene)-4-azafluorene bromide and dimethyl acetylenedicarboxylate.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1653–1659, December, 1978.     

Cyanoethylation of 3-methyl-2-azafluorene

3-Methyl-9,9-di(-cyanoethyl)-2-azafluorene was obtained from 3-methyl-2-azafluorene via the Michael reaction and was converted to the dibasic acid and its diester. Dieckmann condensation of the latter and subsequent hydrolysis gave 3-methyl-4-oxospiro(2-azafluorene-9,1-cyclohexane).Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1668–1670, December, 1972.     

Synthesis of 2-methyl(phenyl)-6-methyl-7-phenylindolisine and 2-methyl(phenyl)indolisino-[6,7-a]indene

Substituted indolisines were obtained from 2-methyl-, 2-ethoxymethyl-, and 2-phenoxymethyl-5-methyl-4-phenylpyridines. 3-Methyl-2-azafluorene was used in the syntheses of a four-ring condensed system — substituted indolisino[6,7-a]indene.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1395–1397, October, 1971.     

Synthesis of 4,5,6,6a-tetrahydro-8-azafluoranthenes

The partially hydrogenated condensed cyclohexano-8-azafluoranthene system is formed as a result of cyclodehydration of 3-methyl-9,9-di(2-carboxyethyl)-2-azafluorene. A substituted partially hydrogenated 8-azafluoranthene was obtained from the product by opening of the cyclohexane ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 215–219, February, 1976.     

Mass spectrometric study of 4-azafluorenes

The dissociative ionization of 4-azafluorene and its methyl and phenyl derivatives was investigated. The relative intensity of the [M — CH₃]⁺ ion peak depends on the position of the CH₃ group in the 4-azafluorene ring. It was established that the loss of an RCN particle (R=H, CH₃, and C₆H₅) for unsubstituted 4-azafluorene takes place from the M⁺ and [M — H]⁺ ion, exclusively from the [M — H]⁺ ion for the methyl-substituted compounds, and from the [M — H]⁺ and [H — 2H]⁺ fragments for the phenyl-substituted derivatives. Randomization of the deuterium ions in the 9,9-d₂-4-azafluorene molecular ion was observed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 246–250, February, 1978.     

Substituted pyridines

5-Methyl-4-phenyl-2-styryipyridine has been oxidized to 5-methyl-4-phenylpyridinie-2-carboxylic acid. The decarboxylation of this acid has given 3-methyl-4-phenylpyrldine. To prove the structure of -(5-methyl-4-phenyl-2-pyridyl)acetophenone, it has been converted into 2, 5-dimethyl-4-phenylpyridine. The reaction of benzyl chloride with the lithium derivative of 2, 5-dimethyl-4-phenylpyridine has been studied. 3,7-Dimethyl-2-azafluorene has been obtained from 2,5-dimethyl-4-p-tolylpyridine.     

2-(ω-Hydroxyalkyl)-3-methylindanO[2,1-c]piperidines

Two isomers of 3-methylindano[2,1-c]piperidine were isolated in the reduction of 3-methyl-2-azafluorene with sodium in alcohol. N-(-Hydroxyalkyl) derivatives of this heterocyclic system were obtainedTranslated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 666–668, May, 1972.     

Azomethines of nitrogen-containing heterocycles. I. Synthesis and study of the structures of schiff bases from 3-methyl-2-azafluorenone and arylamines

In an investigation of the conditions for the formation of Schiff bases from 3-methyl-2-azafluorenone and arylamines it was shown that the use of boron trifluoride etherate as the catalyst insures the highest yields. The fundamental possibility of the preparation of Schiff bases by condensation of 3-methyl-2-azafluorene with p-nitrosodimethylaniline and subsequent reduction of the resulting oxazirane structure is demonstrated. The ratio of the cis and trans isomers of the resulting azomethines was established on the basis of PMR spectral data.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 109–115, January, 1976.     

Mass spectrometric study of 2-azafluorenes

The fragmentation of 2-azafluorene and its methyl and phenyl-substituted derivatives was studied. It is shown that ejection of an RCN fragment (R=CH₃, C₆H₅) by the molecular ions leads to a more intense peak if R is in the 3 position of the azafluorene ring. It was established that, in contrast to the dissociative ionization of fluorene, all of the ions of which are formed from the (M-H)⁺ fragment, the fragmentation of 2-azafluorene and its derivative also takes place from the molecular ion. Randomization of the deuterium atoms attached to C₉ with the remaining hydrogen atoms was observed.Translated from Khimiya Geterotisiklicheskikh Soedinenii, No. 1, pp. 101–105, January, 1977.