Facile synthesis of isoxazoline-bispirooxindoles via the 1,3-dipolar cycloaddition of nitrile oxides with isoindigos.

An efficient 1,3-dipolar cycloaddition of nitrile oxides and isoindigos has been disclosed, enabling straightforward access to diverse isoxazoline-bispirooxindoles with vicinal quaternary spirocenters in moderate to excellent yields with high diastereoselectivity. This protocol exhibits a broad substrate scope, excellent functional group compatibility, mild reaction conditions, and operational simplicity. Moreover, a gram-scale reaction followed by subsequent transformations further highlights the practical utility of this approach.