Advances in Catalyst Design for β-Lactone Formation via Ring-Expansion Carbonylation.

Over the past three decades, β-lactones have emerged as valuable intermediates for producing diverse industrial chemicals and biodegradable polymers. The ring-expansion carbonylation (REC) of epoxides has become an atom-economical and direct approach to β-lactone production, leveraging readily available carbon monoxide and epoxides. While homogeneous catalysts, particularly bimetallic [Lewis acid][Lewis base]-type systems, have demonstrated exceptional activity and selectivity, issues like recycling and separation limit the industrial scalability. Heterogenized catalysts offer advantages such as ease of separation and reusability but suffer from reduced efficiency. Recent advancements in porous polymer-based heterogeneous systems, including immobilized cobaltate anions, address these challenges by combining high surface areas with enhanced catalytic performance. Herein, we explore the evolution of homogeneous to heterogeneous REC catalysts, highlighting emerging porous materials and their potential for scalable β-lactone synthesis. Future directions emphasize overcoming the remaining barriers to establish robust, efficient, and sustainable catalytic processes.