Box-copper catalyzed asymmetric inverse-electron-demand oxa-hetero-Diels–Alder reaction for efficient synthesis of spiro pyranyl-oxindole derivatives

A chiral Box/Cu catalyzed asymmetric IEDDA reaction between isatin-derived β,γ-unsaturated α-ketoesters and electron-rich olefins was developed, which provided chiral spiro oxindole-pyrans in excellent yields with excellent stereoselectivities.