Study of the Fischer cyclization of diarylhydrazones and related secondary hydrazones I. Relative orienting capacity of the p-methyl and p-methoxy groups of diarylhydrazines

γ-Carbolines and their hydrogenated derivatives. 2.* Hydrogenated derivatives of γ-carbolines: methods of synthesis (review)

“…Thus, during the Fischer cyclization of N,N-diphenylhydrazones substituted differently at the p-positions by Me and MeO groups a mixture of 5-aryl-γ-carboline derivatives is formed. The observed intramolecular competition indicates that the orienting ability of the substituents in the aromatic ring increases in the order H < Me < MeO (1:1.5:4.5) [57]. The presence of electron-accepting substituents requires more severe conditions for condensation.…”