Condition-Controlled Selective Synthesis of Benzo[b]azocinones or 2-Alkenylquinolines via Formal [5 + 3] or [5 + 1] Annulation of 2-Alkenylanilines with Cyclopropenones.

Presented herein is a condition-controlled selective synthesis of benzo[b]azocinones or 2-alkenylquinolines through C-H bond activation-initiated formal [5 + 3] or [5 + 1] annulation of 2-alkenylanilines with cyclopropenones. The selectivity toward different products could be precisely tuned by simply changing the reaction conditions to make the reaction proceed through distinct pathways. Based on these reactions, an atom-economical and robust protocol for the divergent functionalization of alkenyl C(sp2)-H bond was developed, allowing rapid and selective assembly of two classes of valuable N-heterocyclic frameworks. In addition, the methodology is readily scalable, and the structure of products could be diversely elaborated. Moreover, the benzo[b]azocinone derivatives thus obtained were found to possess strong anticancer activity comparable with that of the positive control 5-FU.