Cascade Oxidative Dearomatization/Semipinacol Rearrangement: An Approach to 2‐Spirocyclo‐3‐oxindole Derivatives

Indole derivatives are probably one of the most common kinds of heterocyclic motifs in biologically active natural products and pharmaceutical compounds, among which the substituted oxindoles, referred to as “prominent scaffolds,” play an important part. Although numerous approaches have been developed for the synthesis of oxindole derivatives, most of them focus on the synthesis of 3-spirocyclo-2-oxindoles. In fact, the 2-spirocyclo-3-oxindoles also exist widely in natural products, such as aristotelone, fluorocarpamine, and brevianamide (Scheme 1). However,