Intermolecular Synthesis of Coumarins from Acid Chlorides and Unactivated Alkynes through Palladium Catalysis

We describe a modular synthetic pathway to directly obtain coumarins from acid chlorides and alkynes. A Pd catalyst employing 3,5-CF3-Ph-DPEPhos as the ancillary ligand was found to unlock this reactivity, enabling the conversion of a variety of 2-methoxy benzoyl chlorides and alkynes to the corresponding coumarins. Besides acid chlorides, the in situ generation of this reactive species from the corresponding acid was also possible. Finally, control experiments and preliminary kinetic analyses were performed to understand the role of the catalyst.