Aryltrifluoroborates

Aryltrifluoroborates are organoboron compounds that consist of an aryl group bound to a trifluoroborate moiety, typically existing as salts such as potassium or sodium aryltrifluoroborates (ArBF3−K+ or ArBF3−Na+). They are commonly prepared from arylboronic acids (ArB(OH)2) by treatment with potassium hydrogen difluoride (KHF2) to furnish the corresponding aryltrifluoroborate salts, which can then be isolated and handled as stable solids.

These salts are valued for their stability and handling advantages compared with boronic acids and boronate esters. They are broadly tolerant of air and moisture, exhibit extended shelf life, and can be used as convenient surrogates for boron-based nucleophiles in a range of modern transformations. Their primary prominence is in cross-coupling chemistry, especially Suzuki–Miyaura reactions, where ArBF3− salts participate as aryl sources under catalytic Pd or Ni systems. Activation by fluoride or base facilitates transmetallation from boron to the metal center, enabling efficient C–C bond formation in aqueous, organic, or mixed solvent systems and under relatively mild conditions.

In addition to cross-coupling, aryltrifluoroborates have been employed in radical and photoredox protocols, as well as in other boron-centered transformations, where their stability and tunable reactivity offer practical advantages. Substitution patterns on the aryl ring are diverse, enabling broad scope with heteroaryl and electron-rich or -deficient substrates. Limitations can include the need for specific catalysts or activators and variable reactivity depending on substituents or reaction conditions.

See also: boronic acids, trifluoroborates, Suzuki–Miyaura coupling.