Ru(II)‐Catalyzed C−H Annulation of Imidazo[1,5‐a]quinolines with Alkynes: A Direct Route to Functionalized Quinolizines

Ru(II)‐catalyzed oxidative annulation of imidazo[1,5‐a]quinoline with alkynes via double C−H activation to produce highly functionalized quinolizines is reported. This reaction featured high efficiency and a relatively wide substrate scope, further has been successfully utilized in the late‐stage functionalization and diversification of annulated products. The reaction is highly chemoselective and regioselective. In addition, the use of biomass‐derived solvent as a reaction medium, the catalyst can be recycled a number of times. Interestingly, most of the annulated products exhibit intense fluorescence emission at a broad range and their photophysical property could be tuned by restricting the intramolecular motion in aqueous media and showing AIE‐active properties. They also exhibit a selective fluorescent response towards Cu2+. Further photocatalytic properties of the π‐extended product are demonstrated in the oxidative azolation of unactivated arenes.