Abstract
Propiolates cyclotrimerize in the presence of catalytic amounts of gold nanoparticles to give aryl benzoates in high yields and with turnover frequencies of thousands per hour. Types of alkynes other than propiolates do not react, and, if molecular oxygen is present and dissociated by the gold nanoparticles, electron-rich arenes engage with the propiolate to form a new C-C bond. The activation of propiolates and electron-rich arenes to form C-C bonds, beyond gold-catalyzed Michael additions, constitutes a new example of how and where gold nanoparticles modify the electronic density of unsaturated C-C bonds and opens the door to future transformations.