4-Formylphenylboronic Acid | CAS 87199-17-5 | ≥98%

Suzuki–Miyaura cross-coupling and orthogonal bifunctionality: 4-Formylphenylboronic acid is a widely used aryl boronic acid in palladium-catalysed Suzuki–Miyaura cross-coupling reactions, enabling efficient formation of biaryl and heteroaryl scaffolds bearing a free aldehyde group. The para-aldehyde is fully compatible with standard Suzuki conditions — it survives the coupling event intact, providing a ready-made functional handle for downstream elaboration via reductive amination, Schiff base condensation, Wittig olefination, or oxidation to the carboxylic acid. This orthogonal bifunctionality — boronic acid for C–C coupling, aldehyde for C–N or C=C bond formation — enables sequential, modular construction of complex molecular architectures from a single compact reagent. The compound also participates in palladacycle-catalysed cross-coupling with carboxylic anhydrides and acyl chlorides to form biaryl ketones, and in palladium-catalysed aerobic oxidative cross-coupling reactions where the boronic acid acts as both the nucleophilic partner and a mild reductant under oxygen atmosphere.

Multicomponent and copper-catalysed reactions: The aldehyde group enables 4-formylphenylboronic acid to participate directly in multicomponent reactions that simultaneously exploit both functional groups. In triethylamine-catalysed three-component Hantzsch condensations, the aldehyde serves as the carbonyl component while the boronic acid remains available for subsequent cross-coupling — providing a powerful one-pot strategy for generating structurally diverse dihydropyridine libraries. The compound undergoes copper-mediated ligandless aerobic fluoroalkylation with fluoroalkyl iodides — replacing the boronic acid group with a perfluoroalkyl chain under mild, ligand-free conditions, producing fluoroalkylated benzaldehydes of high value in medicinal chemistry and materials science. Additional copper-catalysed transformations include ligand-free coupling with nitroarenes and copper-catalysed nitration reactions.

Biosensors, surface functionalisation, and catecholamine extraction: The dual functionality of 4-formylphenylboronic acid is extensively exploited in biosensor fabrication. The aldehyde group enables covalent attachment to amine-functionalised surfaces via Schiff base (imine) condensation, while the boronic acid provides the diol-recognition element for selective saccharide or catecholamine binding. This strategy has been applied in the preparation of self-assembled monolayers (SAMs) on gold electrodes — creating boronic acid-functionalised surfaces for electrochemical glucose and fructose sensing. In magnetic nanoparticle-based extraction, Fe₃O₄ particles coated with polyethyleneimine (PEI) are functionalised with 4-formylphenylboronic acid through Schiff base conjugation, producing Fe₃O₄@PEI-FPBA composites with high adsorption capacity (3.45 mg/g for epinephrine) and specific selectivity for catecholamines — dopamine, epinephrine, and norepinephrine — from human urine, enabling clinical diagnostic applications.

β-Lactamase inhibition and pharmaceutical analytical chemistry: Boronic acids are established inhibitors of serine β-lactamases — enzymes responsible for bacterial resistance to β-lactam antibiotics. 4-Formylphenylboronic acid has been specifically identified as an AmpC β-lactamase inhibitor (Weston et al., J. Med. Chem. 1998, 41, 4577), exploiting the reversible covalent interaction between the boronic acid group and the catalytic serine residue. The compound is also catalogued as an analytical reference standard for pharmaceutical impurity profiling of β₁-selective adrenergic receptor blockers used in the treatment of hypertension and heart failure. Its well-characterised crystal structure (Fronczek et al., Acta Crystallogr. C 2001, 57, 1423) further supports its use as a crystallographic reference material.

Dye-sensitised solar cells and materials science: 4-Formylphenylboronic acid is used in the preparation of sensitisers with dithiafulvenyl electron-donor units for high-efficiency dye-sensitised solar cells (DSSCs). The aldehyde group provides the anchoring point for condensation with electron-donating subunits, while the boronic acid enables Suzuki-mediated attachment to the conjugated chromophore core. These push–pull sensitiser architectures are designed to harvest visible light efficiently and inject electrons into TiO₂ photoanodes.