[Formula: see text]-catalyzed [Formula: see text] annulation between 3-oxirane-indolin-2-ones and nitrones to construct spiro[1,4,2-dioxazinan]oxindoles.

[Formula: see text]-catalyzed [Formula: see text] annulation between 3-oxirane-indolin-2-ones and nitrones to construct spiro[1,4,2-dioxazinan]oxindoles.