Divergent Annulations via Organocatalysis: Remote-Controlled and Switchable Reactions of Pyrrolidinone-Based Morita–Baylis–Hillman Carbonates with 2-Arylideneindane-1,3-diones
Rongzhen Li, Xuling Chen, Pengfei Li
Abstract
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[ c ]pyrrole-6,2′-indene]-8-carboxylates, while PPh 3 catalysis redirects the reaction pathway toward a unprecedented (3 + 2)-annulation between C ε and C ε′, generating synthetically valuable (spiro[cyclopenta[ b ]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.