2-Bromophenylboronic Acid | CAS 244205-40-1 | ≥98%

2-Bromophenylboronic Acid (2-bromobenzeneboronic acid, o-bromophenylboronic acid). The ortho relative positioning of the boronic acid and aryl bromide determines the properties and reactive profile of this compound (Lewis acidity, substrate approach, chemoselectivity, and intramolecular/sequential coupling behaviour).

The product may contain small amounts of the cyclic anhydride 2-bromophenylboroxine; under aqueous or basic coupling conditions the two forms re-equilibrate and the impact on yield is minor.

Applications and Reactions

• Suzuki–Miyaura coupling at the boronic acid: couples with suitably chosen aryl and heteroaryl electrophiles under matched Pd/phosphine/base conditions to install an ortho-bromoaryl group on the coupled scaffold. When the aryl bromide is intended for a subsequent intramolecular step, catalyst and electrophile choice should be selected to avoid premature oxidative addition at the retained Ar–Br bond.
• Tandem Suzuki / intramolecular arylation to fused frameworks: after Suzuki coupling, the retained ortho-Ar–Br can be used in intramolecular Pd-catalysed C–H arylation or related ring-closing arylation sequences. Reported chemistry includes fused-purine and phenanthridine-type systems prepared through consecutive Suzuki coupling with 2-bromophenylboronic acid followed by intramolecular C–H arylation; related tandem Suzuki/C–H arylation methods give fluoranthene-type polycyclic aromatics.
• Iterative cross-coupling with boron-masking strategy: where the reverse sequence is needed, the boronic acid can first be masked as its anthranilamide (AAM) boronate. The AAM-protected boronyl group is inactive under Suzuki conditions, allowing coupling at the aryl bromide before deprotection reveals the boronic acid for the next step.
• Organocatalyst for direct amidation of carboxylic acids: 2-bromophenylboronic acid is a documented member of the Hall ortho-halogenoarylboronic acid catalyst family for direct amide formation from carboxylic acids and amines. Under the reported room-temperature dichloromethane / 4 Å molecular sieve conditions, the bromo catalyst is active but less effective than the corresponding ortho-iodo catalyst and the optimised MIBA catalyst.
• Organocatalyst for Diels–Alder reactions of α,β-unsaturated and 2-alkynoic carboxylic acids: 2-bromophenylboronic acid catalyses these Diels–Alder reactions by reversible boronic-acid activation of the carboxyl group. It is reported for acrylic-acid Diels–Alder chemistry and was found to be the most efficient catalyst in the screened set for [4+2] cycloadditions of 2-alkynoic acids, where boronic-acid activation lowers the dienophile LUMO through a mixed acyl boronate intermediate.

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.