Mechanistic Investigation into the Pd-Catalysed C–H Bond Functionalisation of Fluoroarenes: Reaction Kinetics and Intermediate Characterisation

The project aimed to reveal mechanistic details of the Pd-catalysed direct arylation reaction involving fluoroarenes. Direct arylation methodologies have rapidly developed over the last decade as cost-effective, eco-friendly and sustainable alternatives to cross-coupling reactions. Fluoroarenes are attractive substrates due to the fluorine-substitution effect as well as the ability to control the regioselectivity of C–H bond activation by the ortho-fluorine effect. Understanding the reaction mechanisms are crucial for making improvements to the C–H bond functionalisation field and provides access to unique reactivities. A literature reaction condition and the setup for the direct arylation reaction of iodoarene with fluoroarene was tailored for monitoring the progress by in situ FT-IR spectroscopic analysis. Kinetic information regarding the relationship between the reaction rate and factors such as concentrations, temperature, C–H bond strength and the electronic properties of the substrates were established. The catalytically relevant species were identified by in situ NMR spectroscopy, and ex situ MS. The reactivities of these species were confirmed by stoichiometric reactions and the ability to act as a catalyst.