Divergent C–H Annulation for Multifused N‐Heterocycles: Regio‐ and Stereospecific Cyclizations of N‐Alkynylindoles

Abstract N‐Alkynylindoles were divergently cyclized for the synthesis of multifused N‐heterocycles. An ortho ‐aryl palladium species was added to the α position of an ynamine to generate ( Z )‐6‐alkylidene/benzylidene‐6 H ‐isoindolo[2,1‐ a ]indoles, while Pt‐catalyzed β‐addition through π‐activation gave 5‐alkyl/arylindolo[2,1‐ a ]isoquinolines. Double cyclizations using PdCl 2 and oxidant afforded bright yellow benzo[7,8]indolizino[2,3,4,5‐ ija ]quinolines, the synthesis of which was also demonstrated in a different synthetic route.