Electrophilic substitution in indoles. Part IX. Rearrangements and isotope effects in some reactions of tetrahydrocarbazoles

Abstract

7-Methoxytetrahydrocarbazole undergoes acid catalysed equilibration with the isomeric indolenine-3-spirocyclopentane at temperatures over 100°. The synthesis of specifically deuteriated compounds enabled deuterium isotope effects in these reactions to be studied, the secondary isotope effect K_H/K_D was found to be 1·13. This result made possible a refinement in the calculation of the relative importance of the two mechanisms of electrophilic substitution in 6-methoxyindole.