Friedel-Crafts chemistry. Part 40. An expedient novel synthesis of some dibenz-azepines, -azocines, 11 H-benzo( f)pyrido(2,3-b)azepines and 6 H-benzo( g)pyrido(2,3-c)azocines

A new synthetic approach for the synthesis of novel 5 H-dibenz( b,f )azepine, 5 H-dibenz( b,f )- azocine, 11 H-benzo( f)pyrido(2,3-b)azepine and 6 H-benzo( g)pyrido(2,3-c)azocine derivatives is reported. The key step of this methodology is based on Friedel-Crafts ring closure of nitrogen containing carboxylic acids and alkanols in the presence of AlCl 3, P 2O5 or PPA catalysts in overall high yields. The starting carboxylic acids were prepared via an unequivocal synthetic pathway by the basic hydrolysis of trimethyloxindole followed by N-arylation reactions.