Cobalt(II)‐Catalyzed C(sp2)—H Alkynylation/Annulation with Terminal Alkynes: Selective Access to 3‐Methyleneisoindolin‐1‐one.

The cobalt(II)-oxalate-catalyzed reaction between arylacetylenes and N-protected arylamides with pyridin N-oxide as the directing group furnishes the title compounds in good to high yields and in a E/Z-selective manner (Z).