3,4-Difluorophenylboronic | CAS 168267-41-2 | ≥98%

3,4-Difluorophenylboronic Acid (3,4-difluorobenzeneboronic acid) carries adjacent fluorines at the 3- and 4-positions: the meta-fluorine contributes strong inductive withdrawal at the boron-bearing carbon, while the para-fluorine adds a weaker net withdrawal. The 3,4-difluorophenyl C–F pair tunes lipophilicity, metabolic stability, dipole, conformational preference, π-stacking, and molecular recognition in derived products, and acts as a built-in 19F NMR tracer. Used as a 3,4-difluorophenyl building block in medicinal chemistry, agrochemicals, fluorinated π-conjugated materials, and liquid-crystal precursors.

May contain small amounts of the cyclic anhydride 3,4-difluorophenylboroxine. Under aqueous or basic coupling conditions the two forms re-equilibrate and the impact on yield is minor.

Applications and Reactions

• Suzuki–Miyaura coupling: with aryl, heteroaryl, or alkenyl electrophiles to give 3,4-difluorophenyl biaryls, heterobiaryls, terphenyls, and styrenyl products; reported in fluorinated nucleoside scaffolds, enzyme-inhibitor intermediates, and π-conjugated materials.
• Chan–Lam coupling: copper-mediated C–N and C–O arylation onto amines, amides, sulfonamides, carbamates, N–H heterocycles, and phenols.
• Petasis borono-Mannich reaction: three-component coupling with an amine and a carbonyl to give α-aryl amines, α-amino acids, or β-amino alcohols bearing the 3,4-difluorophenyl group, metal-free.
• Nickel-catalysed aryl transfer to aldehydes: addition to aryl aldehydes giving fluorinated diarylmethanols and access to difluorinated benzhydryl alcohol motifs.
• Diazaborinine formation: condensation with diamines to give conjugated fluorinated diazaborinine systems.
• Liebeskind–Srogl-type coupling: aryl partner in oxo-directed coupling with α-oxo ketene dithioacetal substrates.
• Substitution with enyne derivatives: reported with selected enyne acetates and carbonates.
• Non-classical arylation: with arenediazonium salts, diaryliodonium salts, and hypervalent iodine reagents.
• 19F NMR tracer: the installed 3,4-difluorophenyl group serves as a 19F reporter for tracking the target molecule in binding studies, metabolism, and complex mixtures.
• Materials and liquid-crystal precursors: 3,4-difluorophenyl source for biaryl, terphenyl, chromophore, ligand, and liquid-crystal intermediates.
• Protected boronate esters: precursor to pinacol (Bpin), neopentyl glycol, and MIDA esters for iterative cross-coupling.
• Ipso-halodeboronation: to 4-bromo-, 4-chloro-, or 4-iodo-1,2-difluorobenzene under electrophilic halogenation.
• Oxidative hydroxylation: to 3,4-difluorophenol under aerobic photoredox, peroxide, or copper-catalysed conditions.

Further Reading

For boronic acids, boronic esters, protodeboronation, boroxine content, and Suzuki–Miyaura reagent selection, see NorrChemica's Lab Journal guide: Choosing Your Boron Source for Suzuki–Miyaura Coupling.