Divergent Annulations via Organocatalysis: Remote-Controlled and Switchable Reactions of Pyrrolidinone-Based Morita–Baylis–Hillman Carbonates with 2-Arylideneindane-1,3-diones

Developing versatile synthons for diversity-oriented synthesis is of great interest, and the switchable divergent transformations of these synthons pose a challenging task. Herein, we report the first organocatalytic remote-controlled divergent annulations of pyrrolidinone-based Morita-Baylis-Hillman carbonates with 2-arylideneindane-1,3-diones. Through precise catalyst control, this transformative platform enables selective access to distinct spirocyclic architectures: 4-dimethylaminopyridine catalysis orchestrates a formal (5 + 2)-annulation between C^β and C^ε, delivering structurally complex spiro[cyclohepta[<i>c</i>]pyrrole-6,2'-indene]-8-carboxylates, while PPh₃ catalysis redirects the reaction pathway toward a unprecedented (3 + 2)-annulation between C^ε and C^ε', generating synthetically valuable (spiro[cyclopenta[<i>b</i>]pyrrole-6,2'-inden]-3-yl)acrylates. This dual catalytic system not only expands the synthetic utility of MBH carbonates via remote control but also establishes a versatile method for accessing structurally diverse spiroheterocycles.