Nickel‐Catalyzed Regioselective C─H Alkynylation of Pyridones and Isoquinolinones Using Alkynyl Bromides

Abstract A straightforward and efficient protocol for the regioselective C─H alkynylation of 2‐pyridones and isoquinolinones with bromoalkynes under nickel catalysis is described. The alkynylation reaction is enabled by a simple and inexpensive Ni(OTf) 2 / t Bu bpy catalyst system and uses easily accessible bromoalkynes. The protocol demonstrates a broad substrate scope with up to 95% yield (42 examples) and accommodates synthetically valuable functionalities, such as halides, trifluoromethyl, nitrile, ether, thioether, alkyl silanes, and alkene, as well as heteroarene moieties like pyridinyl, furanyl, and thiophenyl. The pyridinyl directing group on alkynylated 2‐pyridones can be smoothly removed to give C6‐alkynylated free NH ‐pyridone. Preliminary mechanistic studies suggest that the alkynylation proceeds via a 2e − oxidative addition pathway involving crucial C─H activation.