Domino C–H Activation/Directing Group Migration/Alkyne Annulation: Unique Selectivity by d6‑Cobalt(III) Catalysts

Distinct selectivity control in Cp*CoIII-catalyzed domino C–H activation/pyridine directing group migration/alkyne annulation has been accomplished through the nucleophilicity of an organometallic cobalt intermediate with a d6 electron configuration. Detailed mechanistic studies provided compelling evidence for a facile C–H activation along with a favorable migration of the directing group for the Cp*CoIII catalysis, rather than the β-oxygen elimination observed for a (CO)3MnI manifold.