Alkene hydromagnesiation is a classic organometallic reaction that allows for the generation of synthetically valuable Grignard reagents. In recent years, new iron catalyzed variants of this reaction that proceed through transfer hydrometallation of the alkene have been reported by Thomas and Greenhalgh and coworkers (J. Am. Chem. Soc. <b>2012</b>, 1304, 11900-11903). A relatively narrow substrate scope, electron-rich vinyl arenes without α- or β-vinyl substitution, limit the reactions broader synthetic utility. Preliminary mechanistic analyses have not led to a sufficient mechanistic understanding allowing rational improvement to the reaction. Here, we use operando infrared spectroscopy to study the bis(imino)pyridine–iron catalyzed hydromagnesiation of vinyl arenes. Our studies using both initial rates kinetic analyses and global modeling have revealed important factors that explain the origin of vinyl arene electronic dependencies as well as branched versus linear addition selectivity.<br/>

Iron-catalyzed transfer hydromagnesiation of vinyl arenes: Mechanistic insights and indications of competing alkene insertion pathways

2019 Spring National Meeting

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