Mechanistic insight into homogeneous catalytic reactions by ESI-MS: Pdcatalyzed cross-coupling reactions

For the study of homogeneous catalytic reaction mechanisms, the ideal technique would becapable of identifying and measuring in real time the abundances of all components of thereaction mixture, including reactants, products, byproducts, intermediates, and catalystresting states. We developed a method to transform electrospray ionization massspectrometry into just such a tool. A method named PSI (pressurized sample infusion)1 wasdeveloped to introduce air- and moisture-sensitive reaction mixtures to the ESI-MS.Application of this technique allowed us to obtain kinetic and mechanistic information onseveral transformations including the Sonogashira2 and Suzuki cross-coupling reactions,hydrodehalogenation of arenes, 3 and an amino acid deprotection.1 Here, we briefly introducethe key components of PSI-ESI-MS, and related investigative tools which we employ toextract the mechanistic information on catalytic systems.