3-Chlorophenylboronic Acid | CAS 63503-60-6 | ≥98%

Suzuki–Miyaura cross-coupling and sequential functionalisation: 3-Chlorophenylboronic acid is a widely used meta-substituted aryl boronic acid in palladium-catalysed Suzuki–Miyaura cross-coupling reactions, enabling efficient construction of 3-chlorobiaryl scaffolds from aryl, heteroaryl, and vinyl halides or pseudohalides. The meta-chloro substitution pattern offers a moderate electron-withdrawing inductive effect that enhances the electrophilicity of the boron centre and promotes efficient transmetalation, while imposing no steric hindrance on the coupling event. A key strategic advantage is that the C–Cl bond at the meta position survives the initial Suzuki coupling intact, leaving it available as a secondary reactive handle for a second Suzuki coupling, Buchwald–Hartwig amination, nucleophilic aromatic substitution (SNAr), or palladium-catalysed cyanation — enabling controlled, stepwise construction of highly substituted biaryl and terphenyl architectures from a single building block. The compound is also compatible with Suzuki–Miyaura reactions using dibromotrifluoromethylbenzene as the electrophilic partner, providing access to trifluoromethyl-substituted chlorobiphenyls relevant to agrochemical and pharmaceutical programmes.

HIF-PHD inhibitor synthesis: 3-Chlorophenylboronic acid is a documented key intermediate in the industrial synthesis of oral hypoxia-inducible factor prolyl hydroxylase (HIF-PHD) inhibitors approved for the treatment of symptomatic anaemia associated with chronic kidney disease (CKD) in adults on chronic maintenance dialysis. In the published synthesis route, the boronic acid undergoes palladium-catalysed Suzuki coupling with a 3,5-dichloropyridine glycinate intermediate using Pd(dppf)Cl₂ as catalyst and K₂CO₃ as base in DMF at 60 °C, installing the 3-chlorophenyl ring at the C-5 position of the pyridine scaffold (CN105837502A). The remaining chlorine at C-3 of the pyridine is then displaced by methoxide in a subsequent substitution step, followed by ester hydrolysis to deliver the final active pharmaceutical ingredient.

PDE4 inhibitor and phthalide synthesis: This boronic acid is employed in the synthesis of PDE4 (phosphodiesterase-4) inhibitors — a class of anti-inflammatory agents under active investigation for respiratory, dermatological, and neurological indications. PDE4 catalyses the hydrolysis of cyclic AMP (cAMP), and its inhibition elevates intracellular cAMP levels, suppressing inflammatory cytokine release. 3-Chlorophenylboronic acid provides the 3-chloroaryl fragment present in several PDE4 inhibitor scaffolds via Suzuki coupling. The compound is also used in the preparation of phthalide derivatives — lactone-containing bicyclic structures that serve as privileged scaffolds in medicinal chemistry, accessible through carbonylative Suzuki coupling or directed ortho-metalation / cyclisation sequences.

Conjugate addition and unconventional cross-coupling: 3-Chlorophenylboronic acid participates in rhodium- or palladium-catalysed 1,4-conjugate addition reactions with ethenesulfonamides, delivering β-aryl ethanesulfonamide products — a structural motif found in bioactive molecules. The meta-chlorine substituent is retained in the product for subsequent derivatisation. The compound also undergoes cross-coupling reactions with diazoesters under palladium catalysis, providing access to α-aryl-α-diazoacetate intermediates used in carbene insertion chemistry, cyclopropanation, and C–H functionalisation. Additionally, coupling with potassium cyanate (KOCN) has been demonstrated, enabling the synthesis of aryl isocyanates and carbamate derivatives directly from the boronic acid.

Materials science and functional polymers: 3-Chlorobiaryl products derived from Suzuki coupling of this boronic acid serve as monomers and intermediates in the synthesis of conjugated polymers, liquid crystalline materials, and organic electronic components. The meta-substitution pattern provides a non-linear geometry in the resulting biaryl, which can be exploited to tune molecular packing, solubility, and optoelectronic properties. The retained C–Cl bond in the coupling product also enables post-polymerisation functionalisation — a strategy used to modify conjugated polymer backbones after chain assembly.