Base‐Catalyzed Michael Addition of 3‐(Acetylpyrazolyl) Oxindoles to Maleimides: Access to Oxindole Scaffolds With Vicinal Quaternary‐Tertiary Stereocenters

A novel tertiary amine‐catalyzed Michael addition strategy was developed to synthesize oxindoles bearing vicinal quaternary‐tertiary stereocenters. 3‐(Acetylpyrazolyl) oxindoles derivatives were designed as highly reactive C3 synthons for base‐catalyzed reactions. These derivatives undergo Michael addition with N‐substituted maleimides to construct oxindole skeletons with vicinal stereocenters. Under mild conditions, the reaction affords a broad range of products in up to 98% yield with dr up to 20:1. The broad substrate scope and gram‐scale reaction highlight the synthetic utility and practicality of this method.