We herein report that PtCl4 has proven to be a hydroarylation catalyst with an efficiency and substrate scope superior to previously known methods. This catalyst demonstrated consistent performance with arene–yne substrates of diverse structural features, including propargyl ethers, propargylamines, and alkynoate esters, providing good to excellent yields of the 6-endo products (chromenes, dihydroquinolines, and coumarins). In contrast, Pt (II), ...