Cobalt-Catalyzed Annulation Reactions of Alkylidenecyclopropanes: Access to Spirocyclopropanes at Room Temperature.

A bidentate chelation-assisted cobalt-catalyzed C(sp2)-H activation and annulation of benzamides and alkylidenecyclopropanes (ACPs) has been realized. The unique reactivity of organocobalt species led to selective migratory insertion across the more electron-rich C═C bond of the ACP followed by faster reductive elimination from the seven-membered cobaltacycle leading to spiro-dihydroisoquinoline derivatives with conservation of the cyclopropyl ring. The operationally simple reaction conditions allowed the C-H activation of both aryl and heteroaryl amides at room temperature.