A series of indole-fused medium-sized N-heterocyclic systems 10a–h were prepared from laboratory-synthesized
indole-based esters 9a–h via intramolecular Friedel–Crafts cyclizations induced by both trifluoromethanesulfonic acid
and AlCl3/CH3NO2 catalysts under suitable conditions. The synthetic sequence to precursors 9a–h that started from simple
N-methylindole-2-carboxylic acid involved conversion to aminoindoles 2a, b, reaction with a,b-unsaturated acid
chlorides to yield acyclic amides 5a–d, ring closure to tricyclic lactams 6a–d, and carbonyl reduction to respective
pyrido and azepino tricyclic amines 7a–d, which finally underwent N-alkylations with a- or b-haloesters to produce the
required ester precursors. The structures of synthesized compounds without stereochemical implications are established
using both spectral and analytical data.