Copper-Catalyzed Preparation of Benzo[3,4]indolo[1,2‑<i>b</i>]isoquinoline-8-ones and Photoluminescence Exploration

A facile synthesis of benzo­[3,4]­indolo­[1,2-b]­isoquinolin-8-ones is described. Under copper catalysis, the reaction proceeds with a high efficiency and a broad reaction scope. A deuteration experiment shows that the KIE value is 2.85. From the results on mechanism studies, copper-catalyzed C–H activation, intramolecular cis-addition of alkynes, and reductive elimination are involved. Moreover, this skeleton is indeed a new fluorophore, and its photophysical properties are also investigated.