Cobalt-Catalyzed Addition of Arylzinc Reagents to Norbornene Derivatives through 1,4-Cobalt Migration

A cobalt-diphosphine catalyst promotes the addition of an arylzinc reagent to a norbornene derivative to I afford o-(2-exo-norbornyl)arylzinc species. This migratory arylzincation reaction is considered to involve insertion of norbornene into an arylcobalt species, alkyl-to-aryl 1,4-cobalt migration, and transmetalation between the resulting o-(2-exo-norbornyl)arylcobalt species and the arylzinc reagent. The o-(2-exo-norbornyl)arylzinc species can be intercepted by common organic electrophiles under copper or palladium catalysis.