FRIEDEL–CRAFTS CHEMISTRY 56*. UNPRECEDENTED CONSTRUCTION OF FUNCTIONALIZED POLYCYCLIC QUINOLINES via FRIEDEL–CRAFTS CYCLIACYLATION AND BECKMANN REARRANGEMENT

Abstract

Construction of functionalized tetracyclic pyrazolo-fused cyclohepta[2,3-h]-, azepino[4,5-h]-, azocino[5,4-h]-, azocino[4,5-h]-, azonino[5,6-h]-, and azocino[2,3-h]quinolinones has been demonstrated by performing intramolecular Friedel–Crafts acylation and Beckmann rearrangement. Trifluoromethanesulfonic or polyphosphoric acid-assisted cyclization of N-heterocyclic acids and esters, synthesized from 1-phenyl-3-(quinolin-8-yl)-1H-pyrazole-4-carbaldehyde, allows to obtain tetracyclic ketones. Further polyphosphoric acid-mediated Beckmann rearrangement of cyclohepta[1,2-h]quinolinone oximes provides the respective lactams in high yields.