Powerful Insight into Catalytic Mechanisms through Simultaneous Monitoring of Reactants, Products, and Intermediates

Keeping an eye on all the players: The combination of bulky phosphonium tags and pressurized sample infusion transforms electrospray ionization mass spectrometry into a tool capable of producing dense data on the relative concentrations of all components of a catalytic reaction, such as the palladium‐catalyzed coupling of an aryl iodide with phenylacetylene (see graph).