MECHANISM OF THE FISCHER INDOLE SYNTHESIS. QUANTUM-CHEMICAL INTERPRETATION OF THE REARRANGEMENT OF SUBSTITUTED CYCLOHEXANONE ARYLHYDRAZONES TO TETRAHYDROCARBAZOLES

Article abstract of DOI:10.1007/BF00522729

Calculations of a number of model structures within the scheme of Fischer 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>-sigma-tropic shift) for the step involving the formation of a carbon-carbon bond in the Fischer reaction is preferred.