FeCl₃-catalyzed [3+3] annulation between 3-oxirane-indolin-2-ones and nitrones to construct spiro[1,4,2-dioxazinan]oxindoles.

An efficient and mild procedure for the synthesis of spiro[1,4,2-dioxazinan]oxindoles has been achieved in high yields by [Formula: see text]-catalyzed annulation of 3-oxirane-indolin-2-ones and nitrones. This catalytic protocol demonstrates that the reaction could tolerate a variety of functional groups and provides convenient access to new structural motifs in good to excellent yields. Moreover, this method featured relatively short reaction time and easy operation.