Pd-catalyzed intramolecular direct arylations at high temperature

Pd-catalyzed cyclodehydrohalogenation involving oxidative addition of aromatic C-Br or activated azaheteroaromatic C-Cl bonds and C(sp(2))-H activation have been investigated at high reaction temperatures (180-200 degrees C). This allowed the fast (10-30 min) synthesis of a variety of azaheteroaromatic ring systems (dibenzo[f,h]phthalazine, dibenzo[f,h]cinnoline, benzofuro[2,3-d]pyridazine, 5H-pyridazino[4,5-b]-indole, 7H-indolo[2,3-c]quinoline and 5H-delta-carboline) in moderate to good yields. (C) 2008 Elsevier Ltd. All rights reserved.