Reactivity of 5-(3-azidophenyl)-1-(1H-pyrrol-3-yl)pyrroles in TFMSA.: A route for new ring systems as DNA-interactive agents

Acid catalyzed decomposition of 5-(3-azidophenyl)-1-(1H-pyrrol-3-yl)pyrroles did not afford the expected dipyrrolo[2,1-a:3,4c]-isoquinoline derivatives, but the planar dipyrrolo[2,1-a:3,2-c]isoquinoline derivatives and related non planar derivatives 11bH-dipyrrolo[2,1-a:3,2-c]isoquinoline derivatives. In strong acid media (trifluoromethanesulfonic acid) the (alpha-(1-pyrrol-3yl) position even if blocked, was more prone to undergo cyclization with respect to the free beta one. Despite the steric hindrance, these compounds were obtained in oderate to good overall yields, depending on the nature and position of the substituents on the 1-(1H-pyrrolyl) moiety. (C) 2001 Elsevier Science Ltd. All rights reserved.