Ruthenium-Catalyzed Synthesis of Isoquinolones with 8‑Aminoquinoline as a Bidentate Directing Group in C–H Functionalization

Ruthenium-catalyzed oxidative annulation of <i>N</i>-quinolin-8-yl-benzamides with alkynes in open air has been achieved using 8-aminoquinolinyl moiety as a bidentate directing group in the presence of Cu­(OAc)₂·H₂O as an oxidant. This reaction offers a broad substrate scope, and both symmetrical and unsymmetrical alkynes can be applied. High regioselectivity was achieved in the case of unsymmetrical (aryl)­alkynes. Reaction with heteroaryl amides was also successful in this catalytic process. A ruthenium-<i>N</i>-quinolin-8-yl-benzamide complex was isolated in the absence of alkyne; in the absence of both <i>N</i>-quinolin-8-yl-benzamide and alkyne, <i>in contrast to literature</i>, only the monoacetate complex RuCl­(OAc)­(<i>p</i>-cymene), but not the bis-acetate complex Ru­(OAc)₂(<i>p</i>-cymene), was isolated. These data suggest that this reaction may proceed via <i>N</i>,<i>N</i>-bidentate chelate complex. Key products were characterized by X-ray crystallography