C6H5BF3X

C6H5BF3X is a chemical formula representing a class of organoboron compounds. The core structure consists of a phenyl group (C6H5) bonded to a trifluoroborate anion ([BF3]-). The "X" in the formula indicates a placeholder for a cation, which can vary. These compounds are often referred to as phenyltrifluoroborates or phenylboronates.

The phenyltrifluoroborate moiety is typically synthesized by reacting phenylboronic acid with a fluoride source, such as potassium fluoride, in the presence of a suitable counterion. The resulting compound often exists as a salt. The nature of the cation (X) influences the physical properties of the compound, such as solubility and stability. Common cations include alkali metals like potassium (C6H5BF3K) or lithium.

Phenyltrifluoroborates are valuable reagents in organic synthesis, particularly in cross-coupling reactions such as the Suzuki-Miyaura coupling. They are generally more stable and easier to handle than their corresponding boronic acids, making them attractive alternatives for certain synthetic transformations. Their reactivity in these coupling reactions is attributed to the electrophilic nature of the boron atom, which can undergo transmetalation with palladium catalysts. The electron-withdrawing fluorine atoms enhance the Lewis acidity of the boron center.