2,5-Dibromophenylboronic Acid

Technical Specifications

Product Description & Scientific Applications

2,5-Dibromophenylboronic Acid ((2,5-Dibromophenyl)boronic Acid, 2,5-Dibromobenzeneboronic Acid) is a trifunctional arylboronic acid building block with two positionally and electronically non-equivalent aryl bromide handles.

Applications and Reactions

• Suzuki–Miyaura coupling: as an arylboronic acid, couples with suitably chosen aryl, heteroaryl, and alkenyl halides or triflates under Pd-catalysed basic conditions to give biaryl, heterobiaryl, and styrene-type products. Because the internal C2 and C5 aryl bromides are themselves potential Pd-oxidative-addition sites, chemoselective coupling at the boronate with retention of both Ar–Br handles is not the automatic outcome of generic Suzuki conditions: it requires deliberately designed conditions (catalyst/ligand choice, base, controlled stoichiometry of the external electrophile, temperature) that favour transmetalation from the boronic acid over oxidative addition into the internal C–Br bonds.
• Sequential cross-coupling on a trifunctional scaffold: after the initial coupling at the boronic acid position under conditions that preserve the Ar–Br bonds, the two remaining C–Br bonds at C2 and C5 are available for sequential Pd-catalysed transformations (Suzuki, Stille, Negishi, Sonogashira, Heck, Buchwald–Hartwig amination, Miyaura borylation), enabling the construction of unsymmetrically trisubstituted phenylene cores from a single building block.
• Protected-boronate lithiation / electrophile-trapping chemistry: the dibromoarylboron framework is related to protected dihalophenylboronate systems (e.g. dihalophenyl dioxazaborocines) used in low-temperature lithiation followed by electrophile trapping, a route to functionalised dihalophenylboronic acid derivatives when the boron centre is suitably protected. This chemistry is best described for suitably protected boronate systems; the unprotected B(OH)₂ form should not be assumed to tolerate organolithium conditions without a substrate-specific procedure.
• Suzuki polycondensation (SPC) monomer: with one boronic acid and two aryl bromides on the same ring, this is an AB₂ monomer. It self-condenses under Suzuki conditions without a comonomer, giving hyperbranched polyarylenes terminated in aryl bromide end groups. The two bromides are inequivalent — ortho (C2) and meta (C5) to boron — so the branching is irregular rather than symmetric. The bromo-terminated periphery is a handle for further functionalisation.
• Chan–Lam-type C–N and C–O coupling: class-level arylboronic-acid chemistry. With Cu(OAc)₂ or related Cu(II) systems and an amine, amide, sulfonamide, carbamate, phenol, or selected alcohol partner under mild aerobic conditions, gives the corresponding N-aryl or O-aryl product at the boronic acid carbon, with the two C–Br bonds normally retained.
• Petasis borono-Mannich reaction: class-level arylboronic-acid chemistry. The boronic acid acts as the aryl donor in a three-component coupling with an amine and an aldehyde, glyoxylic acid, or α-hydroxy aldehyde partner to give arylated amines, including α-aryl glycine and β-amino alcohol scaffolds carrying the 2,5-dibromophenyl group where the substrate is compatible.

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.

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