Highly stereo- and enantio‑selective synthesis of spiro cyclopropyl oxindoles via organic catalyst-mediated cyclopropanation

Spiro-cyclopropyl oxindoles are widely found in natural products and medicinal molecules. Herein, we report a highly stereo- and enantio‑selective procedure for accessing this class of compounds via tertiary amine mediated cyclopropanation of ammonium ylides with the in-situ Heck reaction-generated 3-alkenyl indolones as the Michael receptors. This reaction features mild conditions, excellent enantioselectivity (up to 98 %) and diastereoselectivity (up to 99:1), high atom- and step-economy, broad substrate scopes, and good functional group tolerance. Additionally, this scalable synthetic process could offer a novel strategy for the efficient synthesis of enantiopure spirocyclopropyl oxindoles.