Fischer Synthesis of 1-; 5-; and 7-Substituted 3-(N-Acylamino)-2-phenylindoles

Arylhydrazones were obtained by the reaction of arylhydrazines with -(N-acylamino)acetophenones and were converted into 3-(N-acylamino)-2-phenylindoles with substituents at positions 1, 5, 6, and 7 by Fischer cyclization.     

Indoles

It has been found that the enamine obtained from N,N-dimethylphenylhydrazine and cyclohexanone under the conditions of the Fischer reaction rearranges into N-methyl-1,2,3,4-tetrahydrocarbazole with the liberation of methylamine.For part IV, see [1].     

Indoles

In a study of the Fischer cyclization of cyclohexanone mono-p-substituted α, α-diphenylhydrazones (in which the substituents were donor and acceptor groups) it was found that isomeric (formed during cyclization at the substituted and unsubstituted rings) indoles are formed in close ratios. The results were interpreted in terms of sigmatropic processes as a confirmation of the Fischer reaction via a scheme involving a sigmatropic shift.     

Mechanism of the Fischer indole synthesis. Quantum-chemical interpretation of the rearrangement of substituted cyclohexanone arylhydrazones to tetrahydrocarbazoles

Calculations of a number of model structures within the scheme of the Fishcer indole synthesis were made on the basis of a bonding variant of perturbation theory in the self-consistent-field (SCF) MO LCAO method. A quantum-chemical interpretation of the effect of substituents on the course of the thermal process is given. The kinetics of the thermal and acid-catalyzed indolization of substituted cyclohexanone arylhydrazones to tetrahydrocarbazoles were studied by spectrophotometry. It was shown that the experimental data are in satisfactory agreement with the calculated values. It was concluded that a concerted mechanism (a [3,3]-sigmatropic shift) for the step involving the formation of a carbon-carbon bond in the Fischer reaction is preferred.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 898–907, July, 1986.     

Mechanism of the Fischer reaction. Rearrangement of cyclohexanone N-methylphenylhydrazone and N,N′-dimethyl-N-phenyl-N′-(1-cyclohexenyl)hydrazine to 9-methyl-1,2,3,4-tetrahydrocarbazole

The kinetics of the thermal and acid-catalyzed Fischer reaction of cyclohexanone N-methylphenylhydrazone and N,N-dimethyl-N-pheny1-N-(1-cyclohexenyl)hydrazine were studied by a spectrophotometric method. Formation of the carbon-carbon bond proceeds by a [3,3]-sigmatropic shift mechanism. This conclusion was confirmed by MINDO/3 calculations of the rearrangement of a model divinylhydrazine.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 779–787, June, 1985.     

The cyclization of 5-chloro-2-pentanone with hydrazines

It is shown that the comparative basicities of the - and -nitrogen atoms in -chloroketone hydrazones exert a considerable influence on the course of the intramolecular cyclization.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1273–1275, September, 1970.     

Effect of structural factors on the disintegration of the molecular ions of nitrophenylisoxazoles during electron impact

The dissociative ionization of some nitrophenylisoxazoles was investigated. The effect of the energy of the ionizing electrons and the temperature of the inlet system on the elimination of NO by the molecular ion is examined. On the basis of a comparison of the intensities of the peaks of the (M-NO)⁺ ions, the presence of a correlation between the probability of detachment of NO from the molecular ion and the stability of the cyclic conjugated structures with localization of the charge on the oxygen atom is demonstrated.     

Mechanism of the fischer reaction. Effect of electronic factors on the kinetics of the rearrangement of m-substituted cyclohexanone arylhydrazones to tetrahydrocarbazoles

The kinetics of the thermal and acid-catalyzed Fischer indolization of m-substituted cyclohexanone arylhydrazones were studied. It was shown that substituents with different natures (-CH₃, -Cl) and the polarity of the solvent have little effect on the rate of the rearrangement. The results obtained were interpreted within the framework of a concerted mechanism for the formation of the carbon-carbon bond ([3,3]-sigmatropic rearrangement).Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1207–1212, September, 1985.