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

Distinct selectivity control in Cp*Co-III-catalyzed domino C-H activation/pyridine directing group migration/alkyne annulation has been accomplished through the nucleophilicity of an organometallic cobalt intermediate with a d(6) 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*Co-III catalysis, rather than the beta-oxygen elimination observed for a (CO)(3)Mn-I manifold.