Lewis acid catalyzed annulation of spirocyclic donor–acceptor cyclopropanes with <i>exo</i>-heterocyclic olefins: access to highly functionalized bis-spirocyclopentane oxindole frameworks

Abstract

Lewis acid catalyzed highly efficient [3+2] annulation of spirocyclic Donor-Acceptor cyclopropanes (DACs) with exo-heterocyclic olefins is reported to furnish various biologically relevant dispiro-2,3-dioxopyrrolidine[cyclopentane]oxindole and dispiropyrazolone[cyclopentane]oxindole frameworks. This report highlights the use of oxindole-activated spiro-DACs as potential synthons to access complex dispirocarbocyclic oxindoles via ring-enlargement of the former, with high yields and diastereoselectivity.