Direct Access to Benzolactams and Benzolactones via Nickel Catalyzed Carbonylation with CO.

A new nickel catalyzed cross-electrophile coupling for accessing γ-lactams (isoindolinones) as well as γ-lactones (isobenzofuranones) via carbonylation with CO is documented. The protocol exploits the synergistic role of redox-active Ni(II) complexes and AlCl as a CO activator/oxygen scavenger, leading to the formation of a wide range of cyclic amides and esters (28 examples) in good to high yields (up to 87 %). A dedicated computational investigation revealed the multiple roles played by AlCl. In particular, the simultaneous transient protection of the pendant amino group of the starting reagents and the formation of the electrophilically activated CO-AlCl adduct are shown to concur in paving the way for an energetically favorable mechanistic pathway.