Palladium-Catalyzed Solid-State Polyfluoroarylation of Aryl Halides Using Mechanochemistry

The Suzuki–Miyaura cross-coupling
between polyfluorinated
arylboron nucleophiles and aryl halides enables the efficient construction
of polyfluorinated structural motifs frequently found in organic materials
and catalysts. A key challenge associated with this transformation
involves the slow transmetalation with weakly nucleophilic polyfluorinated
organoboron reagents, which often reduces the yield of the coupling
products. Here, we show that solid-state high-temperature ball-milling
conditions facilitate a palladium-catalyzed cross-coupling with polyfluorinated
arylboronic acids and pinacol esters employing a simple catalytic
system in the absence of any stoichiometric additives. This reaction
exhibits a broad substrate scope and can be carried out in air, and
the use of large amounts of dry and degassed organic solvents is not
required. The successful cross-coupling of weakly nucleophilic polyfluorinated
organoboron reagents was ascribed to the extremely high concentrations
of the substrates and the catalyst under solid-state conditions.