Synergistic [4 + 1] Spiroannulation and Selective Ring-Opening Strategy toward γ‑Spirolactams

A unique and propitious [4 + 1] spiroannulation of 2-aryl-4H-benzo­[d]­[1,3]­oxazine with maleimide has been delineated, furnishing diversely embellished γ-spirolactams featuring pendant benzyl alcohol via Rh­(III)-catalyzed consecutive ring closing/ring opening followed by regioselective cleavage of the C4–O bond of 1,3-benzoxazine promoted by an in situ generated water maneuver constructing new C–C, C–N, and C–O bonds at a go. A detailed mechanistic study, including a thorough analysis of the incorporation of an extra oxygen source, has been showcased to make this strategy for structurally orchestrated isoindoline-1-one spirosuccinimides.