Gold(III) Catalysis in Ionic Liquids: The Case Study of Coumarin Synthesis

Abstract Well‐defined (P,C)‐cyclometalated Au(III) complexes proved to be able to catalyze the synthesis of coumarins by intramolecular hydroarylation of a broad range of aryl propiolates under mild and practical conditions (0.1–2 mol% catalyst, 25–40 °C, 1–24 hours). The use of an ionic liquid as reaction solvent allowed to drastically decrease the amount of Brönsted acid used to unlock the catalyst regeneration step. The effect of the nature of the acid additive and of the ionic liquid anion have been assessed. Preliminary results on the extension of this methodology to the cyclization of aryl propargyl ethers are also presented.