3-Fluorophenylboronic Acid | CAS 768-35-4 | ≥98%

3-Fluorophenylboronic Acid (3-fluorobenzeneboronic acid, m-fluorophenylboronic acid) carries a meta-fluorine that is more strongly electron-withdrawing than the para isomer (σm +0.34 vs σp +0.06). The aryl C–F tunes lipophilicity, metabolic stability, dipole, and π-stacking in derived products, and acts as a built-in 19F NMR tracer. Used as a 3-fluorophenyl building block in medicinal chemistry, agrochemicals, fluorinated π-conjugated materials, and liquid-crystal precursors.

May contain small amounts of the cyclic anhydride 3-fluorophenylboroxine. 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-fluorophenyl biaryls, heterobiaryls, terphenyls, and styrenyl products.
• Chan–Lam coupling: copper-mediated C–N and C–O arylation onto amines, amides, sulfonamides, N–H heterocycles, and phenols.
• Rhodium-catalysed 1,4-addition: conjugate addition to α,β-unsaturated carbonyls; chiral ligands give enantioenriched β-(3-fluorophenyl) products.
• Petasis borono-Mannich reaction: three-component coupling with an amine and a carbonyl (glyoxylates, α-hydroxy aldehydes) to give α-aryl amines, α-amino acids, or β-amino alcohols, metal-free.
• Diol recognition and saccharide sensing: reversible boronate esters with cis-1,2- and 1,3-diols; lower pKa improves binding to saccharides, catechols, and phosphates near neutral pH.
• Non-classical arylation: with arenediazonium salts, diaryliodonium salts, and hypervalent iodine reagents.
• 19F NMR tracer: the installed 3-fluorophenyl group serves as a 19F reporter for tracking the target molecule in binding studies, metabolism, and complex mixtures.
• Materials and liquid-crystal precursors: 3-fluorophenyl source for biaryl, terphenyl, chromophore, ligand, and liquid-crystal intermediates, regioisomerically distinct from para-fluoro analogues.
• Protected boronate esters: precursor to pinacol (Bpin), neopentyl glycol, and MIDA esters for iterative cross-coupling.
• Ipso-halodeboronation: to 1-bromo-, 1-chloro-, or 1-iodo-3-fluorobenzene under electrophilic halogenation.
• Oxidative hydroxylation: to 3-fluorophenol 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.Note