Ligand Design Enables the Palladium-Catalyzed Intermolecular Carbochlorocarbonylation of Alkynes and Cyclopentenone Formation

Herein, we demonstrate that ligand design enables the direct addition of acid chlorides across alkynes in a single step with complete atom economy to afford α,β-unsaturated acid chloride products. This carbochlorocarbonylation reaction, which proceeds through the formal cleavage and reassembly of C-COCl bonds, was developed and explored for a range of acid chlorides and alkynes. During the course of this work, the formation of synthetically useful cyclopentenones through a formal C-H functionalization step was serendipitously observed at elevated temperatures. After optimizing for this divergent reactivity, we explored the substrate scope and undertook experiments to investigate the underlying mechanistic pathway for the formation of this product. Overall, this work expands the carbochlorocarbonylation reaction from activated substrates to alkynes. Further, it provides insight into ligand design for the exploration of fundamental reactivity.