Ru/O 2 -Catalyzed Oxidative C-H Activation/Alkyne Annulation Using Quinoline-Functionalized NHC as a Directing and Functionalizable Group.

The ruthenium/O 2 -catalyzed oxidative annulation reaction of imidazo[1,5- a ]quinolin-2-ium salts with alkynes via N -heterocyclic carbene-directed C-H activation to obtain π-conjugated fused imidazo[1,5- a ]quinolin-2-ium derivatives is reported. Molecular oxygen has been explored as an economic and clean oxidant and an alternative to metal oxidants. The current protocol exhibits a wide range of substrate scope including bioactive (±)-α-tocopherol derivatives. Moreover, most of the annulated products show strong fluorescence properties, indicating their potential for making new light-emitting materials.