Ruthenium-Mediated Dual Catalytic Reactions of Isoquinoline via C−H Activation and Dearomatization for Isoquinolone

We have unraveled the ruthenium‐promoted prototype reaction based on C(sp2)−C(sp3) bond formation through the reigoselective C−H activation of isoquinoline and pyridine derivatives with various alkyl halides, leading to 1‐substituted isoquinoline products in good yield. This C−H catalytic reaction did not rely on chelation assistance of the directing group of the substrates. The dimer [RuCl2(p‐cymene)]2 in combination with an N‐heterocyclic carbene ligand, adamantanecarboxylic acid and K2CO3 base in N‐methyl‐2‐pyrrolidone solution at 150 °C are the best conditions. Simultaneously, we are also able to chemically tune the reaction mode to dearomatization by adding water, leading to isoquinolone products. This reaction methodology is not suitable for other nitrogen‐containing heteroarenes such as pyridazines and pyrimidines.